January 2025 - Linux-stable-mirror

[PATCH] clk: mmp2: call pm_genpd_init() only after genpd.name is set

by Lubomir Rintel

Setting the genpd's struct device's name with dev_set_name() is happening within pm_genpd_init(). If it remains NULL, things can blow up later, such as when crafting the devfs hierarchy for the power domain: 8<--- cut here --- [please do not actually cut, you'll ruin your display] Unable to handle kernel NULL pointer dereference at virtual address 00000000 when read ... Call trace: strlen from start_creating+0x90/0x138 start_creating from debugfs_create_dir+0x20/0x178 debugfs_create_dir from genpd_debug_add.part.0+0x4c/0x144 genpd_debug_add.part.0 from genpd_debug_init+0x74/0x90 genpd_debug_init from do_one_initcall+0x5c/0x244 do_one_initcall from kernel_init_freeable+0x19c/0x1f4 kernel_init_freeable from kernel_init+0x1c/0x12c kernel_init from ret_from_fork+0x14/0x28 Bisecting tracks this crash back to commit 899f44531fe6 ("pmdomain: core: Add GENPD_FLAG_DEV_NAME_FW flag"), which exchanges use of genpd->name with dev_name(&genpd->dev) in genpd_debug_add.part(). Fixes: 899f44531fe6 ("pmdomain: core: Add GENPD_FLAG_DEV_NAME_FW flag") Signed-off-by: Lubomir Rintel <lkundrak(a)v3.sk> Cc: stable(a)vger.kernel.org # v6.12+ --- drivers/clk/mmp/pwr-island.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/clk/mmp/pwr-island.c b/drivers/clk/mmp/pwr-island.c index edaa2433a472..eaf5d2c5e593 100644 --- a/drivers/clk/mmp/pwr-island.c +++ b/drivers/clk/mmp/pwr-island.c @@ -106,10 +106,10 @@ struct generic_pm_domain *mmp_pm_domain_register(const char *name, pm_domain->flags = flags; pm_domain->lock = lock; - pm_genpd_init(&pm_domain->genpd, NULL, true); pm_domain->genpd.name = name; pm_domain->genpd.power_on = mmp_pm_domain_power_on; pm_domain->genpd.power_off = mmp_pm_domain_power_off; + pm_genpd_init(&pm_domain->genpd, NULL, true); return &pm_domain->genpd; } -- 2.47.1

3 months, 3 weeks

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[PATCH] USB: serial: cp210x: add Phoenix Contact UPS Device

by Johan Hovold

Phoenix Contact sells UPS Quint devices [1] with a custom datacable [2] that embeds a Silicon Labs converter: Bus 001 Device 003: ID 1b93:1013 Silicon Labs Phoenix Contact UPS Device Device Descriptor: bLength 18 bDescriptorType 1 bcdUSB 2.00 bDeviceClass 0 bDeviceSubClass 0 bDeviceProtocol 0 bMaxPacketSize0 64 idVendor 0x1b93 idProduct 0x1013 bcdDevice 1.00 iManufacturer 1 Silicon Labs iProduct 2 Phoenix Contact UPS Device iSerial 3 <redacted> bNumConfigurations 1 Configuration Descriptor: bLength 9 bDescriptorType 2 wTotalLength 0x0020 bNumInterfaces 1 bConfigurationValue 1 iConfiguration 0 bmAttributes 0x80 (Bus Powered) MaxPower 100mA Interface Descriptor: bLength 9 bDescriptorType 4 bInterfaceNumber 0 bAlternateSetting 0 bNumEndpoints 2 bInterfaceClass 255 Vendor Specific Class bInterfaceSubClass 0 bInterfaceProtocol 0 iInterface 2 Phoenix Contact UPS Device Endpoint Descriptor: bLength 7 bDescriptorType 5 bEndpointAddress 0x01 EP 1 OUT bmAttributes 2 Transfer Type Bulk Synch Type None Usage Type Data wMaxPacketSize 0x0040 1x 64 bytes bInterval 0 Endpoint Descriptor: bLength 7 bDescriptorType 5 bEndpointAddress 0x82 EP 2 IN bmAttributes 2 Transfer Type Bulk Synch Type None Usage Type Data wMaxPacketSize 0x0040 1x 64 bytes bInterval 0 [1] https://www.phoenixcontact.com/en-pc/products/power-supply-unit-quint-ps-1a… [2] https://www.phoenixcontact.com/en-il/products/data-cable-preassembled-ifs-u… Reported-by: Giuseppe Corbelli <giuseppe.corbelli(a)antaresvision.com> Cc: stable(a)vger.kernel.org Signed-off-by: Johan Hovold <johan(a)kernel.org> --- drivers/usb/serial/cp210x.c | 1 + 1 file changed, 1 insertion(+) diff --git a/drivers/usb/serial/cp210x.c b/drivers/usb/serial/cp210x.c index c24101f0a07a..9960ac2b10b7 100644 --- a/drivers/usb/serial/cp210x.c +++ b/drivers/usb/serial/cp210x.c @@ -223,6 +223,7 @@ static const struct usb_device_id id_table[] = { { USB_DEVICE(0x19CF, 0x3000) }, /* Parrot NMEA GPS Flight Recorder */ { USB_DEVICE(0x1ADB, 0x0001) }, /* Schweitzer Engineering C662 Cable */ { USB_DEVICE(0x1B1C, 0x1C00) }, /* Corsair USB Dongle */ + { USB_DEVICE(0x1B93, 0x1013) }, /* Phoenix Contact UPS Device */ { USB_DEVICE(0x1BA4, 0x0002) }, /* Silicon Labs 358x factory default */ { USB_DEVICE(0x1BE3, 0x07A6) }, /* WAGO 750-923 USB Service Cable */ { USB_DEVICE(0x1D6F, 0x0010) }, /* Seluxit ApS RF Dongle */ -- 2.45.2

3 months, 3 weeks

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[PATCH] gpio: loongson: Fix Loongson-2K2000 ACPI GPIO register offset

by Binbin Zhou

Since commit 3feb70a61740 ("gpio: loongson: add more gpio chip support"), the Loongson-2K2000 GPIO is supported. However, according to the firmware development specification, the Loongson-2K2000 ACPI GPIO register offsets in the driver do not match the register base addresses in the firmware, resulting in the registers not being accessed properly. Now, we fix it to ensure the GPIO function works properly. Cc: stable(a)vger.kernel.org Cc: Yinbo Zhu <zhuyinbo(a)loongson.cn> Fixes: 3feb70a61740 ("gpio: loongson: add more gpio chip support") Co-developed-by: Hongliang Wang <wanghongliang(a)loongson.cn> Signed-off-by: Hongliang Wang <wanghongliang(a)loongson.cn> Signed-off-by: Binbin Zhou <zhoubinbin(a)loongson.cn> --- drivers/gpio/gpio-loongson-64bit.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/drivers/gpio/gpio-loongson-64bit.c b/drivers/gpio/gpio-loongson-64bit.c index 6749d4dd6d64..7f4d78fd800e 100644 --- a/drivers/gpio/gpio-loongson-64bit.c +++ b/drivers/gpio/gpio-loongson-64bit.c @@ -237,9 +237,9 @@ static const struct loongson_gpio_chip_data loongson_gpio_ls2k2000_data1 = { static const struct loongson_gpio_chip_data loongson_gpio_ls2k2000_data2 = { .label = "ls2k2000_gpio", .mode = BIT_CTRL_MODE, - .conf_offset = 0x84, - .in_offset = 0x88, - .out_offset = 0x80, + .conf_offset = 0x4, + .in_offset = 0x8, + .out_offset = 0x0, }; static const struct loongson_gpio_chip_data loongson_gpio_ls3a5000_data = { -- 2.43.5

3 months, 3 weeks

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[withdrawn] mm-zswap-disable-migration-while-using-per-cpu-acomp_ctx.patch removed from -mm tree

by Andrew Morton

The quilt patch titled Subject: mm: zswap: disable migration while using per-CPU acomp_ctx has been removed from the -mm tree. Its filename was mm-zswap-disable-migration-while-using-per-cpu-acomp_ctx.patch This patch was dropped because it was withdrawn ------------------------------------------------------ From: Yosry Ahmed <yosryahmed(a)google.com> Subject: mm: zswap: disable migration while using per-CPU acomp_ctx Date: Tue, 7 Jan 2025 22:22:35 +0000 In zswap_compress() and zswap_decompress(), the per-CPU acomp_ctx of the current CPU at the beginning of the operation is retrieved and used throughout. However, since neither preemption nor migration are disabled, it is possible that the operation continues on a different CPU. If the original CPU is hotunplugged while the acomp_ctx is still in use, we run into a UAF bug as the resources attached to the acomp_ctx are freed during hotunplug in zswap_cpu_comp_dead(). The problem was introduced in commit 1ec3b5fe6eec ("mm/zswap: move to use crypto_acomp API for hardware acceleration") when the switch to the crypto_acomp API was made. Prior to that, the per-CPU crypto_comp was retrieved using get_cpu_ptr() which disables preemption and makes sure the CPU cannot go away from under us. Preemption cannot be disabled with the crypto_acomp API as a sleepable context is needed. Commit 8ba2f844f050 ("mm/zswap: change per-cpu mutex and buffer to per-acomp_ctx") increased the UAF surface area by making the per-CPU buffers dynamic, adding yet another resource that can be freed from under zswap compression/decompression by CPU hotunplug. This cannot be fixed by holding cpus_read_lock(), as it is possible for code already holding the lock to fall into reclaim and enter zswap (causing a deadlock). It also cannot be fixed by wrapping the usage of acomp_ctx in an SRCU critical section and using synchronize_srcu() in zswap_cpu_comp_dead(), because synchronize_srcu() is not allowed in CPU-hotplug notifiers (see Documentation/RCU/Design/Requirements/Requirements.rst). This can be fixed by refcounting the acomp_ctx, but it involves complexity in handling the race between the refcount dropping to zero in zswap_[de]compress() and the refcount being re-initialized when the CPU is onlined. Keep things simple for now and just disable migration while using the per-CPU acomp_ctx to block CPU hotunplug until the usage is over. Link: https://lkml.kernel.org/r/20250107222236.2715883-2-yosryahmed@google.com Fixes: 1ec3b5fe6eec ("mm/zswap: move to use crypto_acomp API for hardware acceleration") Signed-off-by: Yosry Ahmed <yosryahmed(a)google.com> Reported-by: Johannes Weiner <hannes(a)cmpxchg.org> Closes: https://lore.kernel.org/lkml/20241113213007.GB1564047@cmpxchg.org/ Reported-by: Sam Sun <samsun1006219(a)gmail.com> Closes: https://lore.kernel.org/lkml/CAEkJfYMtSdM5HceNsXUDf5haghD5+o2e7Qv4OcuruL4tP… Cc: Barry Song <baohua(a)kernel.org> Cc: Chengming Zhou <chengming.zhou(a)linux.dev> Cc: Kanchana P Sridhar <kanchana.p.sridhar(a)intel.com> Cc: Nhat Pham <nphamcs(a)gmail.com> Cc: syzbot <syzkaller(a)googlegroups.com> Cc: Vitaly Wool <vitalywool(a)gmail.com> Cc: <stable(a)vger.kernel.org> Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> --- mm/zswap.c | 19 ++++++++++++++++--- 1 file changed, 16 insertions(+), 3 deletions(-) --- a/mm/zswap.c~mm-zswap-disable-migration-while-using-per-cpu-acomp_ctx +++ a/mm/zswap.c @@ -880,6 +880,18 @@ static int zswap_cpu_comp_dead(unsigned return 0; } +/* Remain on the CPU while using its acomp_ctx to stop it from going offline */ +static struct crypto_acomp_ctx *acomp_ctx_get_cpu(struct crypto_acomp_ctx __percpu *acomp_ctx) +{ + migrate_disable(); + return raw_cpu_ptr(acomp_ctx); +} + +static void acomp_ctx_put_cpu(void) +{ + migrate_enable(); +} + static bool zswap_compress(struct page *page, struct zswap_entry *entry, struct zswap_pool *pool) { @@ -893,8 +905,7 @@ static bool zswap_compress(struct page * gfp_t gfp; u8 *dst; - acomp_ctx = raw_cpu_ptr(pool->acomp_ctx); - + acomp_ctx = acomp_ctx_get_cpu(pool->acomp_ctx); mutex_lock(&acomp_ctx->mutex); dst = acomp_ctx->buffer; @@ -950,6 +961,7 @@ unlock: zswap_reject_alloc_fail++; mutex_unlock(&acomp_ctx->mutex); + acomp_ctx_put_cpu(); return comp_ret == 0 && alloc_ret == 0; } @@ -960,7 +972,7 @@ static void zswap_decompress(struct zswa struct crypto_acomp_ctx *acomp_ctx; u8 *src; - acomp_ctx = raw_cpu_ptr(entry->pool->acomp_ctx); + acomp_ctx = acomp_ctx_get_cpu(entry->pool->acomp_ctx); mutex_lock(&acomp_ctx->mutex); src = zpool_map_handle(zpool, entry->handle, ZPOOL_MM_RO); @@ -990,6 +1002,7 @@ static void zswap_decompress(struct zswa if (src != acomp_ctx->buffer) zpool_unmap_handle(zpool, entry->handle); + acomp_ctx_put_cpu(); } /********************************* _ Patches currently in -mm which might be from yosryahmed(a)google.com are revert-mm-zswap-fix-race-between-compression-and-cpu-hotunplug.patch

3 months, 3 weeks

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[PATCH RESEND 2/2] mm: zswap: use SRCU to synchronize with CPU hotunplug

by Yosry Ahmed

In zswap_compress() and zswap_decompress(), the per-CPU acomp_ctx of the current CPU at the beginning of the operation is retrieved and used throughout. However, since neither preemption nor migration are disabled, it is possible that the operation continues on a different CPU. If the original CPU is hotunplugged while the acomp_ctx is still in use, we run into a UAF bug as the resources attached to the acomp_ctx are freed during hotunplug in zswap_cpu_comp_dead(). The problem was introduced in commit 1ec3b5fe6eec ("mm/zswap: move to use crypto_acomp API for hardware acceleration") when the switch to the crypto_acomp API was made. Prior to that, the per-CPU crypto_comp was retrieved using get_cpu_ptr() which disables preemption and makes sure the CPU cannot go away from under us. Preemption cannot be disabled with the crypto_acomp API as a sleepable context is needed. Commit 8ba2f844f050 ("mm/zswap: change per-cpu mutex and buffer to per-acomp_ctx") increased the UAF surface area by making the per-CPU buffers dynamic, adding yet another resource that can be freed from under zswap compression/decompression by CPU hotunplug. There are a few ways to fix this: (a) Add a refcount for acomp_ctx. (b) Disable migration while using the per-CPU acomp_ctx. (c) Use SRCU to wait for other CPUs using the acomp_ctx of the CPU being hotunplugged. Normal RCU cannot be used as a sleepable context is required. Implement (c) since it's simpler than (a), and (b) involves using migrate_disable() which is apparently undesired (see huge comment in include/linux/preempt.h). Fixes: 1ec3b5fe6eec ("mm/zswap: move to use crypto_acomp API for hardware acceleration") Cc: <stable(a)vger.kernel.org> Signed-off-by: Yosry Ahmed <yosryahmed(a)google.com> Reported-by: Johannes Weiner <hannes(a)cmpxchg.org> Closes: https://lore.kernel.org/lkml/20241113213007.GB1564047@cmpxchg.org/ Reported-by: Sam Sun <samsun1006219(a)gmail.com> Closes: https://lore.kernel.org/lkml/CAEkJfYMtSdM5HceNsXUDf5haghD5+o2e7Qv4OcuruL4tP… --- mm/zswap.c | 31 ++++++++++++++++++++++++++++--- 1 file changed, 28 insertions(+), 3 deletions(-) diff --git a/mm/zswap.c b/mm/zswap.c index f6316b66fb236..add1406d693b8 100644 --- a/mm/zswap.c +++ b/mm/zswap.c @@ -864,12 +864,22 @@ static int zswap_cpu_comp_prepare(unsigned int cpu, struct hlist_node *node) return ret; } +DEFINE_STATIC_SRCU(acomp_srcu); + static int zswap_cpu_comp_dead(unsigned int cpu, struct hlist_node *node) { struct zswap_pool *pool = hlist_entry(node, struct zswap_pool, node); struct crypto_acomp_ctx *acomp_ctx = per_cpu_ptr(pool->acomp_ctx, cpu); if (!IS_ERR_OR_NULL(acomp_ctx)) { + /* + * Even though the acomp_ctx should not be currently in use on + * @cpu, it may still be used by compress/decompress operations + * that started on @cpu and migrated to a different CPU. Wait + * for such usages to complete, any news usages would be a bug. + */ + synchronize_srcu(&acomp_srcu); + if (!IS_ERR_OR_NULL(acomp_ctx->req)) acomp_request_free(acomp_ctx->req); if (!IS_ERR_OR_NULL(acomp_ctx->acomp)) @@ -880,6 +890,18 @@ static int zswap_cpu_comp_dead(unsigned int cpu, struct hlist_node *node) return 0; } +static struct crypto_acomp_ctx *acomp_ctx_get_cpu(struct crypto_acomp_ctx __percpu *acomp_ctx, + int *srcu_idx) +{ + *srcu_idx = srcu_read_lock(&acomp_srcu); + return raw_cpu_ptr(acomp_ctx); +} + +static void acomp_ctx_put_cpu(int srcu_idx) +{ + srcu_read_unlock(&acomp_srcu, srcu_idx); +} + static bool zswap_compress(struct page *page, struct zswap_entry *entry, struct zswap_pool *pool) { @@ -889,12 +911,12 @@ static bool zswap_compress(struct page *page, struct zswap_entry *entry, unsigned int dlen = PAGE_SIZE; unsigned long handle; struct zpool *zpool; + int srcu_idx; char *buf; gfp_t gfp; u8 *dst; - acomp_ctx = raw_cpu_ptr(pool->acomp_ctx); - + acomp_ctx = acomp_ctx_get_cpu(pool->acomp_ctx, &srcu_idx); mutex_lock(&acomp_ctx->mutex); dst = acomp_ctx->buffer; @@ -950,6 +972,7 @@ static bool zswap_compress(struct page *page, struct zswap_entry *entry, zswap_reject_alloc_fail++; mutex_unlock(&acomp_ctx->mutex); + acomp_ctx_put_cpu(srcu_idx); return comp_ret == 0 && alloc_ret == 0; } @@ -958,9 +981,10 @@ static void zswap_decompress(struct zswap_entry *entry, struct folio *folio) struct zpool *zpool = entry->pool->zpool; struct scatterlist input, output; struct crypto_acomp_ctx *acomp_ctx; + int srcu_idx; u8 *src; - acomp_ctx = raw_cpu_ptr(entry->pool->acomp_ctx); + acomp_ctx = acomp_ctx_get_cpu(entry->pool->acomp_ctx, &srcu_idx); mutex_lock(&acomp_ctx->mutex); src = zpool_map_handle(zpool, entry->handle, ZPOOL_MM_RO); @@ -990,6 +1014,7 @@ static void zswap_decompress(struct zswap_entry *entry, struct folio *folio) if (src != acomp_ctx->buffer) zpool_unmap_handle(zpool, entry->handle); + acomp_ctx_put_cpu(srcu_idx); } /********************************* -- 2.47.1.613.gc27f4b7a9f-goog

3 months, 3 weeks

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+ zram-fix-potential-uaf-of-zram-table.patch added to mm-hotfixes-unstable branch

by Andrew Morton

The patch titled Subject: zram: fix potential UAF of zram table has been added to the -mm mm-hotfixes-unstable branch. Its filename is zram-fix-potential-uaf-of-zram-table.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patche… This patch will later appear in the mm-hotfixes-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next via the mm-everything branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there every 2-3 working days ------------------------------------------------------ From: Kairui Song <kasong(a)tencent.com> Subject: zram: fix potential UAF of zram table Date: Tue, 7 Jan 2025 14:54:46 +0800 If zram_meta_alloc failed early, it frees allocated zram->table without setting it NULL. Which will potentially cause zram_meta_free to access the table if user reset an failed and uninitialized device. Link: https://lkml.kernel.org/r/20250107065446.86928-1-ryncsn@gmail.com Fixes: 74363ec674cb ("zram: fix uninitialized ZRAM not releasing backing device") Signed-off-by: Kairui Song <kasong(a)tencent.com> Reviewed-by: Sergey Senozhatsky <senozhatsky(a)chromium.org> Cc: <stable(a)vger.kernel.org> Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> --- drivers/block/zram/zram_drv.c | 1 + 1 file changed, 1 insertion(+) --- a/drivers/block/zram/zram_drv.c~zram-fix-potential-uaf-of-zram-table +++ a/drivers/block/zram/zram_drv.c @@ -1468,6 +1468,7 @@ static bool zram_meta_alloc(struct zram zram->mem_pool = zs_create_pool(zram->disk->disk_name); if (!zram->mem_pool) { vfree(zram->table); + zram->table = NULL; return false; } _ Patches currently in -mm which might be from kasong(a)tencent.com are zram-fix-potential-uaf-of-zram-table.patch mm-memcontrol-avoid-duplicated-memcg-enable-check.patch mm-swap_cgroup-remove-swap_cgroup_cmpxchg.patch mm-swap_cgroup-remove-global-swap-cgroup-lock.patch mm-swap_cgroup-decouple-swap-cgroup-recording-and-clearing.patch mm-swap-minor-clean-up-for-swap-entry-allocation.patch mm-swap-fold-swap_info_get_cont-in-the-only-caller.patch mm-swap-remove-old-allocation-path-for-hdd.patch mm-swap-use-cluster-lock-for-hdd.patch mm-swap-clean-up-device-availability-check.patch mm-swap-clean-up-plist-removal-and-adding.patch mm-swap-hold-a-reference-during-scan-and-cleanup-flag-usage.patch mm-swap-use-an-enum-to-define-all-cluster-flags-and-wrap-flags-changes.patch mm-swap-reduce-contention-on-device-lock.patch mm-swap-simplify-percpu-cluster-updating.patch mm-swap-introduce-a-helper-for-retrieving-cluster-from-offset.patch mm-swap-use-a-global-swap-cluster-for-non-rotation-devices.patch mm-swap_slots-remove-slot-cache-for-freeing-path.patch

3 months, 3 weeks

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+ selftests-mm-set-allocated-memory-to-non-zero-content-in-cow-test.patch added to mm-hotfixes-unstable branch

by Andrew Morton

The patch titled Subject: selftests/mm: set allocated memory to non-zero content in cow test has been added to the -mm mm-hotfixes-unstable branch. Its filename is selftests-mm-set-allocated-memory-to-non-zero-content-in-cow-test.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patche… This patch will later appear in the mm-hotfixes-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next via the mm-everything branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there every 2-3 working days ------------------------------------------------------ From: Ryan Roberts <ryan.roberts(a)arm.com> Subject: selftests/mm: set allocated memory to non-zero content in cow test Date: Tue, 7 Jan 2025 14:25:53 +0000 After commit b1f202060afe ("mm: remap unused subpages to shared zeropage when splitting isolated thp"), cow test cases involving swapping out THPs via madvise(MADV_PAGEOUT) started to be skipped due to the subsequent check via pagemap determining that the memory was not actually swapped out. Logs similar to this were emitted: ... # [RUN] Basic COW after fork() ... with swapped-out, PTE-mapped THP (16 kB) ok 2 # SKIP MADV_PAGEOUT did not work, is swap enabled? # [RUN] Basic COW after fork() ... with single PTE of swapped-out THP (16 kB) ok 3 # SKIP MADV_PAGEOUT did not work, is swap enabled? # [RUN] Basic COW after fork() ... with swapped-out, PTE-mapped THP (32 kB) ok 4 # SKIP MADV_PAGEOUT did not work, is swap enabled? ... The commit in question introduces the behaviour of scanning THPs and if their content is predominantly zero, it splits them and replaces the pages which are wholly zero with the zero page. These cow test cases were getting caught up in this. So let's avoid that by filling the contents of all allocated memory with a non-zero value. With this in place, the tests are passing again. Link: https://lkml.kernel.org/r/20250107142555.1870101-1-ryan.roberts@arm.com Fixes: b1f202060afe ("mm: remap unused subpages to shared zeropage when splitting isolated thp") Signed-off-by: Ryan Roberts <ryan.roberts(a)arm.com> Acked-by: David Hildenbrand <david(a)redhat.com> Cc: Usama Arif <usamaarif642(a)gmail.com> Cc: Yu Zhao <yuzhao(a)google.com> Cc: <stable(a)vger.kernel.org> Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> --- tools/testing/selftests/mm/cow.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) --- a/tools/testing/selftests/mm/cow.c~selftests-mm-set-allocated-memory-to-non-zero-content-in-cow-test +++ a/tools/testing/selftests/mm/cow.c @@ -758,7 +758,7 @@ static void do_run_with_base_page(test_f } /* Populate a base page. */ - memset(mem, 0, pagesize); + memset(mem, 1, pagesize); if (swapout) { madvise(mem, pagesize, MADV_PAGEOUT); @@ -824,12 +824,12 @@ static void do_run_with_thp(test_fn fn, * Try to populate a THP. Touch the first sub-page and test if * we get the last sub-page populated automatically. */ - mem[0] = 0; + mem[0] = 1; if (!pagemap_is_populated(pagemap_fd, mem + thpsize - pagesize)) { ksft_test_result_skip("Did not get a THP populated\n"); goto munmap; } - memset(mem, 0, thpsize); + memset(mem, 1, thpsize); size = thpsize; switch (thp_run) { @@ -1012,7 +1012,7 @@ static void run_with_hugetlb(test_fn fn, } /* Populate an huge page. */ - memset(mem, 0, hugetlbsize); + memset(mem, 1, hugetlbsize); /* * We need a total of two hugetlb pages to handle COW/unsharing _ Patches currently in -mm which might be from ryan.roberts(a)arm.com are mm-clear-uffd-wp-pte-pmd-state-on-mremap.patch selftests-mm-set-allocated-memory-to-non-zero-content-in-cow-test.patch selftests-mm-add-fork-cow-guard-page-test-fix.patch selftests-mm-introduce-uffd-wp-mremap-regression-test.patch

3 months, 3 weeks

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+ revert-mm-zswap-fix-race-between-compression-and-cpu-hotunplug.patch added to mm-hotfixes-unstable branch

by Andrew Morton

The patch titled Subject: Revert "mm: zswap: fix race between [de]compression and CPU hotunplug" has been added to the -mm mm-hotfixes-unstable branch. Its filename is revert-mm-zswap-fix-race-between-compression-and-cpu-hotunplug.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patche… This patch will later appear in the mm-hotfixes-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next via the mm-everything branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there every 2-3 working days ------------------------------------------------------ From: Yosry Ahmed <yosryahmed(a)google.com> Subject: Revert "mm: zswap: fix race between [de]compression and CPU hotunplug" Date: Tue, 7 Jan 2025 22:22:34 +0000 This reverts commit eaebeb93922ca6ab0dd92027b73d0112701706ef. Commit eaebeb93922c ("mm: zswap: fix race between [de]compression and CPU hotunplug") used the CPU hotplug lock in zswap compress/decompress operations to protect against a race with CPU hotunplug making some per-CPU resources go away. However, zswap compress/decompress can be reached through reclaim while the lock is held, resulting in a potential deadlock as reported by syzbot: ====================================================== WARNING: possible circular locking dependency detected 6.13.0-rc6-syzkaller-00006-g5428dc1906dd #0 Not tainted ------------------------------------------------------ kswapd0/89 is trying to acquire lock: ffffffff8e7d2ed0 (cpu_hotplug_lock){++++}-{0:0}, at: acomp_ctx_get_cpu mm/zswap.c:886 [inline] ffffffff8e7d2ed0 (cpu_hotplug_lock){++++}-{0:0}, at: zswap_compress mm/zswap.c:908 [inline] ffffffff8e7d2ed0 (cpu_hotplug_lock){++++}-{0:0}, at: zswap_store_page mm/zswap.c:1439 [inline] ffffffff8e7d2ed0 (cpu_hotplug_lock){++++}-{0:0}, at: zswap_store+0xa74/0x1ba0 mm/zswap.c:1546 but task is already holding lock: ffffffff8ea355a0 (fs_reclaim){+.+.}-{0:0}, at: balance_pgdat mm/vmscan.c:6871 [inline] ffffffff8ea355a0 (fs_reclaim){+.+.}-{0:0}, at: kswapd+0xb58/0x2f30 mm/vmscan.c:7253 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (fs_reclaim){+.+.}-{0:0}: lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5849 __fs_reclaim_acquire mm/page_alloc.c:3853 [inline] fs_reclaim_acquire+0x88/0x130 mm/page_alloc.c:3867 might_alloc include/linux/sched/mm.h:318 [inline] slab_pre_alloc_hook mm/slub.c:4070 [inline] slab_alloc_node mm/slub.c:4148 [inline] __kmalloc_cache_node_noprof+0x40/0x3a0 mm/slub.c:4337 kmalloc_node_noprof include/linux/slab.h:924 [inline] alloc_worker kernel/workqueue.c:2638 [inline] create_worker+0x11b/0x720 kernel/workqueue.c:2781 workqueue_prepare_cpu+0xe3/0x170 kernel/workqueue.c:6628 cpuhp_invoke_callback+0x48d/0x830 kernel/cpu.c:194 __cpuhp_invoke_callback_range kernel/cpu.c:965 [inline] cpuhp_invoke_callback_range kernel/cpu.c:989 [inline] cpuhp_up_callbacks kernel/cpu.c:1020 [inline] _cpu_up+0x2b3/0x580 kernel/cpu.c:1690 cpu_up+0x184/0x230 kernel/cpu.c:1722 cpuhp_bringup_mask+0xdf/0x260 kernel/cpu.c:1788 cpuhp_bringup_cpus_parallel+0xf9/0x160 kernel/cpu.c:1878 bringup_nonboot_cpus+0x2b/0x50 kernel/cpu.c:1892 smp_init+0x34/0x150 kernel/smp.c:1009 kernel_init_freeable+0x417/0x5d0 init/main.c:1569 kernel_init+0x1d/0x2b0 init/main.c:1466 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244 -> #0 (cpu_hotplug_lock){++++}-{0:0}: check_prev_add kernel/locking/lockdep.c:3161 [inline] check_prevs_add kernel/locking/lockdep.c:3280 [inline] validate_chain+0x18ef/0x5920 kernel/locking/lockdep.c:3904 __lock_acquire+0x1397/0x2100 kernel/locking/lockdep.c:5226 lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5849 percpu_down_read include/linux/percpu-rwsem.h:51 [inline] cpus_read_lock+0x42/0x150 kernel/cpu.c:490 acomp_ctx_get_cpu mm/zswap.c:886 [inline] zswap_compress mm/zswap.c:908 [inline] zswap_store_page mm/zswap.c:1439 [inline] zswap_store+0xa74/0x1ba0 mm/zswap.c:1546 swap_writepage+0x647/0xce0 mm/page_io.c:279 shmem_writepage+0x1248/0x1610 mm/shmem.c:1579 pageout mm/vmscan.c:696 [inline] shrink_folio_list+0x35ee/0x57e0 mm/vmscan.c:1374 shrink_inactive_list mm/vmscan.c:1967 [inline] shrink_list mm/vmscan.c:2205 [inline] shrink_lruvec+0x16db/0x2f30 mm/vmscan.c:5734 mem_cgroup_shrink_node+0x385/0x8e0 mm/vmscan.c:6575 mem_cgroup_soft_reclaim mm/memcontrol-v1.c:312 [inline] memcg1_soft_limit_reclaim+0x346/0x810 mm/memcontrol-v1.c:362 balance_pgdat mm/vmscan.c:6975 [inline] kswapd+0x17b3/0x2f30 mm/vmscan.c:7253 kthread+0x2f0/0x390 kernel/kthread.c:389 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244 other info that might help us debug this: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(fs_reclaim); lock(cpu_hotplug_lock); lock(fs_reclaim); rlock(cpu_hotplug_lock); *** DEADLOCK *** 1 lock held by kswapd0/89: #0: ffffffff8ea355a0 (fs_reclaim){+.+.}-{0:0}, at: balance_pgdat mm/vmscan.c:6871 [inline] #0: ffffffff8ea355a0 (fs_reclaim){+.+.}-{0:0}, at: kswapd+0xb58/0x2f30 mm/vmscan.c:7253 stack backtrace: CPU: 0 UID: 0 PID: 89 Comm: kswapd0 Not tainted 6.13.0-rc6-syzkaller-00006-g5428dc1906dd #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024 Call Trace: <TASK> __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120 print_circular_bug+0x13a/0x1b0 kernel/locking/lockdep.c:2074 check_noncircular+0x36a/0x4a0 kernel/locking/lockdep.c:2206 check_prev_add kernel/locking/lockdep.c:3161 [inline] check_prevs_add kernel/locking/lockdep.c:3280 [inline] validate_chain+0x18ef/0x5920 kernel/locking/lockdep.c:3904 __lock_acquire+0x1397/0x2100 kernel/locking/lockdep.c:5226 lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5849 percpu_down_read include/linux/percpu-rwsem.h:51 [inline] cpus_read_lock+0x42/0x150 kernel/cpu.c:490 acomp_ctx_get_cpu mm/zswap.c:886 [inline] zswap_compress mm/zswap.c:908 [inline] zswap_store_page mm/zswap.c:1439 [inline] zswap_store+0xa74/0x1ba0 mm/zswap.c:1546 swap_writepage+0x647/0xce0 mm/page_io.c:279 shmem_writepage+0x1248/0x1610 mm/shmem.c:1579 pageout mm/vmscan.c:696 [inline] shrink_folio_list+0x35ee/0x57e0 mm/vmscan.c:1374 shrink_inactive_list mm/vmscan.c:1967 [inline] shrink_list mm/vmscan.c:2205 [inline] shrink_lruvec+0x16db/0x2f30 mm/vmscan.c:5734 mem_cgroup_shrink_node+0x385/0x8e0 mm/vmscan.c:6575 mem_cgroup_soft_reclaim mm/memcontrol-v1.c:312 [inline] memcg1_soft_limit_reclaim+0x346/0x810 mm/memcontrol-v1.c:362 balance_pgdat mm/vmscan.c:6975 [inline] kswapd+0x17b3/0x2f30 mm/vmscan.c:7253 kthread+0x2f0/0x390 kernel/kthread.c:389 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244 </TASK> Revert the change. A different fix for the race with CPU hotunplug will follow. Link: https://lkml.kernel.org/r/20250107222236.2715883-1-yosryahmed@google.com Signed-off-by: Yosry Ahmed <yosryahmed(a)google.com> Reported-by: syzbot <syzkaller(a)googlegroups.com> Cc: Barry Song <baohua(a)kernel.org> Cc: Chengming Zhou <chengming.zhou(a)linux.dev> Cc: Johannes Weiner <hannes(a)cmpxchg.org> Cc: Kanchana P Sridhar <kanchana.p.sridhar(a)intel.com> Cc: Nhat Pham <nphamcs(a)gmail.com> Cc: Sam Sun <samsun1006219(a)gmail.com> Cc: Vitaly Wool <vitalywool(a)gmail.com> Cc: <stable(a)vger.kernel.org> Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> --- mm/zswap.c | 19 +++---------------- 1 file changed, 3 insertions(+), 16 deletions(-) --- a/mm/zswap.c~revert-mm-zswap-fix-race-between-compression-and-cpu-hotunplug +++ a/mm/zswap.c @@ -880,18 +880,6 @@ static int zswap_cpu_comp_dead(unsigned return 0; } -/* Prevent CPU hotplug from freeing up the per-CPU acomp_ctx resources */ -static struct crypto_acomp_ctx *acomp_ctx_get_cpu(struct crypto_acomp_ctx __percpu *acomp_ctx) -{ - cpus_read_lock(); - return raw_cpu_ptr(acomp_ctx); -} - -static void acomp_ctx_put_cpu(void) -{ - cpus_read_unlock(); -} - static bool zswap_compress(struct page *page, struct zswap_entry *entry, struct zswap_pool *pool) { @@ -905,7 +893,8 @@ static bool zswap_compress(struct page * gfp_t gfp; u8 *dst; - acomp_ctx = acomp_ctx_get_cpu(pool->acomp_ctx); + acomp_ctx = raw_cpu_ptr(pool->acomp_ctx); + mutex_lock(&acomp_ctx->mutex); dst = acomp_ctx->buffer; @@ -961,7 +950,6 @@ unlock: zswap_reject_alloc_fail++; mutex_unlock(&acomp_ctx->mutex); - acomp_ctx_put_cpu(); return comp_ret == 0 && alloc_ret == 0; } @@ -972,7 +960,7 @@ static void zswap_decompress(struct zswa struct crypto_acomp_ctx *acomp_ctx; u8 *src; - acomp_ctx = acomp_ctx_get_cpu(entry->pool->acomp_ctx); + acomp_ctx = raw_cpu_ptr(entry->pool->acomp_ctx); mutex_lock(&acomp_ctx->mutex); src = zpool_map_handle(zpool, entry->handle, ZPOOL_MM_RO); @@ -1002,7 +990,6 @@ static void zswap_decompress(struct zswa if (src != acomp_ctx->buffer) zpool_unmap_handle(zpool, entry->handle); - acomp_ctx_put_cpu(); } /********************************* _ Patches currently in -mm which might be from yosryahmed(a)google.com are revert-mm-zswap-fix-race-between-compression-and-cpu-hotunplug.patch mm-zswap-disable-migration-while-using-per-cpu-acomp_ctx.patch

3 months, 3 weeks

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+ mm-zswap-disable-migration-while-using-per-cpu-acomp_ctx.patch added to mm-hotfixes-unstable branch

by Andrew Morton

The patch titled Subject: mm: zswap: disable migration while using per-CPU acomp_ctx has been added to the -mm mm-hotfixes-unstable branch. Its filename is mm-zswap-disable-migration-while-using-per-cpu-acomp_ctx.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patche… This patch will later appear in the mm-hotfixes-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next via the mm-everything branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there every 2-3 working days ------------------------------------------------------ From: Yosry Ahmed <yosryahmed(a)google.com> Subject: mm: zswap: disable migration while using per-CPU acomp_ctx Date: Tue, 7 Jan 2025 22:22:35 +0000 In zswap_compress() and zswap_decompress(), the per-CPU acomp_ctx of the current CPU at the beginning of the operation is retrieved and used throughout. However, since neither preemption nor migration are disabled, it is possible that the operation continues on a different CPU. If the original CPU is hotunplugged while the acomp_ctx is still in use, we run into a UAF bug as the resources attached to the acomp_ctx are freed during hotunplug in zswap_cpu_comp_dead(). The problem was introduced in commit 1ec3b5fe6eec ("mm/zswap: move to use crypto_acomp API for hardware acceleration") when the switch to the crypto_acomp API was made. Prior to that, the per-CPU crypto_comp was retrieved using get_cpu_ptr() which disables preemption and makes sure the CPU cannot go away from under us. Preemption cannot be disabled with the crypto_acomp API as a sleepable context is needed. Commit 8ba2f844f050 ("mm/zswap: change per-cpu mutex and buffer to per-acomp_ctx") increased the UAF surface area by making the per-CPU buffers dynamic, adding yet another resource that can be freed from under zswap compression/decompression by CPU hotunplug. This cannot be fixed by holding cpus_read_lock(), as it is possible for code already holding the lock to fall into reclaim and enter zswap (causing a deadlock). It also cannot be fixed by wrapping the usage of acomp_ctx in an SRCU critical section and using synchronize_srcu() in zswap_cpu_comp_dead(), because synchronize_srcu() is not allowed in CPU-hotplug notifiers (see Documentation/RCU/Design/Requirements/Requirements.rst). This can be fixed by refcounting the acomp_ctx, but it involves complexity in handling the race between the refcount dropping to zero in zswap_[de]compress() and the refcount being re-initialized when the CPU is onlined. Keep things simple for now and just disable migration while using the per-CPU acomp_ctx to block CPU hotunplug until the usage is over. Link: https://lkml.kernel.org/r/20250107222236.2715883-2-yosryahmed@google.com Fixes: 1ec3b5fe6eec ("mm/zswap: move to use crypto_acomp API for hardware acceleration") Signed-off-by: Yosry Ahmed <yosryahmed(a)google.com> Reported-by: Johannes Weiner <hannes(a)cmpxchg.org> Closes: https://lore.kernel.org/lkml/20241113213007.GB1564047@cmpxchg.org/ Reported-by: Sam Sun <samsun1006219(a)gmail.com> Closes: https://lore.kernel.org/lkml/CAEkJfYMtSdM5HceNsXUDf5haghD5+o2e7Qv4OcuruL4tP… Cc: Barry Song <baohua(a)kernel.org> Cc: Chengming Zhou <chengming.zhou(a)linux.dev> Cc: Kanchana P Sridhar <kanchana.p.sridhar(a)intel.com> Cc: Nhat Pham <nphamcs(a)gmail.com> Cc: syzbot <syzkaller(a)googlegroups.com> Cc: Vitaly Wool <vitalywool(a)gmail.com> Cc: <stable(a)vger.kernel.org> Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> --- mm/zswap.c | 19 ++++++++++++++++--- 1 file changed, 16 insertions(+), 3 deletions(-) --- a/mm/zswap.c~mm-zswap-disable-migration-while-using-per-cpu-acomp_ctx +++ a/mm/zswap.c @@ -880,6 +880,18 @@ static int zswap_cpu_comp_dead(unsigned return 0; } +/* Remain on the CPU while using its acomp_ctx to stop it from going offline */ +static struct crypto_acomp_ctx *acomp_ctx_get_cpu(struct crypto_acomp_ctx __percpu *acomp_ctx) +{ + migrate_disable(); + return raw_cpu_ptr(acomp_ctx); +} + +static void acomp_ctx_put_cpu(void) +{ + migrate_enable(); +} + static bool zswap_compress(struct page *page, struct zswap_entry *entry, struct zswap_pool *pool) { @@ -893,8 +905,7 @@ static bool zswap_compress(struct page * gfp_t gfp; u8 *dst; - acomp_ctx = raw_cpu_ptr(pool->acomp_ctx); - + acomp_ctx = acomp_ctx_get_cpu(pool->acomp_ctx); mutex_lock(&acomp_ctx->mutex); dst = acomp_ctx->buffer; @@ -950,6 +961,7 @@ unlock: zswap_reject_alloc_fail++; mutex_unlock(&acomp_ctx->mutex); + acomp_ctx_put_cpu(); return comp_ret == 0 && alloc_ret == 0; } @@ -960,7 +972,7 @@ static void zswap_decompress(struct zswa struct crypto_acomp_ctx *acomp_ctx; u8 *src; - acomp_ctx = raw_cpu_ptr(entry->pool->acomp_ctx); + acomp_ctx = acomp_ctx_get_cpu(entry->pool->acomp_ctx); mutex_lock(&acomp_ctx->mutex); src = zpool_map_handle(zpool, entry->handle, ZPOOL_MM_RO); @@ -990,6 +1002,7 @@ static void zswap_decompress(struct zswa if (src != acomp_ctx->buffer) zpool_unmap_handle(zpool, entry->handle); + acomp_ctx_put_cpu(); } /********************************* _ Patches currently in -mm which might be from yosryahmed(a)google.com are revert-mm-zswap-fix-race-between-compression-and-cpu-hotunplug.patch mm-zswap-disable-migration-while-using-per-cpu-acomp_ctx.patch

3 months, 3 weeks

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+ mm-clear-uffd-wp-pte-pmd-state-on-mremap.patch added to mm-hotfixes-unstable branch

by Andrew Morton

The patch titled Subject: mm: clear uffd-wp PTE/PMD state on mremap() has been added to the -mm mm-hotfixes-unstable branch. Its filename is mm-clear-uffd-wp-pte-pmd-state-on-mremap.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patche… This patch will later appear in the mm-hotfixes-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next via the mm-everything branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there every 2-3 working days ------------------------------------------------------ From: Ryan Roberts <ryan.roberts(a)arm.com> Subject: mm: clear uffd-wp PTE/PMD state on mremap() Date: Tue, 7 Jan 2025 14:47:52 +0000 When mremap()ing a memory region previously registered with userfaultfd as write-protected but without UFFD_FEATURE_EVENT_REMAP, an inconsistency in flag clearing leads to a mismatch between the vma flags (which have uffd-wp cleared) and the pte/pmd flags (which do not have uffd-wp cleared). This mismatch causes a subsequent mprotect(PROT_WRITE) to trigger a warning in page_table_check_pte_flags() due to setting the pte to writable while uffd-wp is still set. Fix this by always explicitly clearing the uffd-wp pte/pmd flags on any such mremap() so that the values are consistent with the existing clearing of VM_UFFD_WP. Be careful to clear the logical flag regardless of its physical form; a PTE bit, a swap PTE bit, or a PTE marker. Cover PTE, huge PMD and hugetlb paths. Link: https://lkml.kernel.org/r/20250107144755.1871363-2-ryan.roberts@arm.com Co-developed-by: Miko��aj Lenczewski <miko.lenczewski(a)arm.com> Signed-off-by: Miko��aj Lenczewski <miko.lenczewski(a)arm.com> Signed-off-by: Ryan Roberts <ryan.roberts(a)arm.com> Closes: https://lore.kernel.org/linux-mm/810b44a8-d2ae-4107-b665-5a42eae2d948@arm.c… Fixes: 63b2d4174c4a ("userfaultfd: wp: add the writeprotect API to userfaultfd ioctl") Cc: David Hildenbrand <david(a)redhat.com> Cc: Jann Horn <jannh(a)google.com> Cc: Liam R. Howlett <Liam.Howlett(a)Oracle.com> Cc: Lorenzo Stoakes <lorenzo.stoakes(a)oracle.com> Cc: Mark Rutland <mark.rutland(a)arm.com> Cc: Muchun Song <muchun.song(a)linux.dev> Cc: Peter Xu <peterx(a)redhat.com> Cc: Shuah Khan <shuah(a)kernel.org> Cc: Vlastimil Babka <vbabka(a)suse.cz> Cc: <stable(a)vger.kernel.org> Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> --- include/linux/userfaultfd_k.h | 12 ++++++++++++ mm/huge_memory.c | 12 ++++++++++++ mm/hugetlb.c | 14 +++++++++++++- mm/mremap.c | 32 +++++++++++++++++++++++++++++++- 4 files changed, 68 insertions(+), 2 deletions(-) --- a/include/linux/userfaultfd_k.h~mm-clear-uffd-wp-pte-pmd-state-on-mremap +++ a/include/linux/userfaultfd_k.h @@ -247,6 +247,13 @@ static inline bool vma_can_userfault(str vma_is_shmem(vma); } +static inline bool vma_has_uffd_without_event_remap(struct vm_area_struct *vma) +{ + struct userfaultfd_ctx *uffd_ctx = vma->vm_userfaultfd_ctx.ctx; + + return uffd_ctx && (uffd_ctx->features & UFFD_FEATURE_EVENT_REMAP) == 0; +} + extern int dup_userfaultfd(struct vm_area_struct *, struct list_head *); extern void dup_userfaultfd_complete(struct list_head *); void dup_userfaultfd_fail(struct list_head *); @@ -401,6 +408,11 @@ static inline bool userfaultfd_wp_async( { return false; } + +static inline bool vma_has_uffd_without_event_remap(struct vm_area_struct *vma) +{ + return false; +} #endif /* CONFIG_USERFAULTFD */ --- a/mm/huge_memory.c~mm-clear-uffd-wp-pte-pmd-state-on-mremap +++ a/mm/huge_memory.c @@ -2206,6 +2206,16 @@ static pmd_t move_soft_dirty_pmd(pmd_t p return pmd; } +static pmd_t clear_uffd_wp_pmd(pmd_t pmd) +{ + if (pmd_present(pmd)) + pmd = pmd_clear_uffd_wp(pmd); + else if (is_swap_pmd(pmd)) + pmd = pmd_swp_clear_uffd_wp(pmd); + + return pmd; +} + bool move_huge_pmd(struct vm_area_struct *vma, unsigned long old_addr, unsigned long new_addr, pmd_t *old_pmd, pmd_t *new_pmd) { @@ -2244,6 +2254,8 @@ bool move_huge_pmd(struct vm_area_struct pgtable_trans_huge_deposit(mm, new_pmd, pgtable); } pmd = move_soft_dirty_pmd(pmd); + if (vma_has_uffd_without_event_remap(vma)) + pmd = clear_uffd_wp_pmd(pmd); set_pmd_at(mm, new_addr, new_pmd, pmd); if (force_flush) flush_pmd_tlb_range(vma, old_addr, old_addr + PMD_SIZE); --- a/mm/hugetlb.c~mm-clear-uffd-wp-pte-pmd-state-on-mremap +++ a/mm/hugetlb.c @@ -5402,6 +5402,7 @@ static void move_huge_pte(struct vm_area unsigned long new_addr, pte_t *src_pte, pte_t *dst_pte, unsigned long sz) { + bool need_clear_uffd_wp = vma_has_uffd_without_event_remap(vma); struct hstate *h = hstate_vma(vma); struct mm_struct *mm = vma->vm_mm; spinlock_t *src_ptl, *dst_ptl; @@ -5418,7 +5419,18 @@ static void move_huge_pte(struct vm_area spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING); pte = huge_ptep_get_and_clear(mm, old_addr, src_pte); - set_huge_pte_at(mm, new_addr, dst_pte, pte, sz); + + if (need_clear_uffd_wp && pte_marker_uffd_wp(pte)) + huge_pte_clear(mm, new_addr, dst_pte, sz); + else { + if (need_clear_uffd_wp) { + if (pte_present(pte)) + pte = huge_pte_clear_uffd_wp(pte); + else if (is_swap_pte(pte)) + pte = pte_swp_clear_uffd_wp(pte); + } + set_huge_pte_at(mm, new_addr, dst_pte, pte, sz); + } if (src_ptl != dst_ptl) spin_unlock(src_ptl); --- a/mm/mremap.c~mm-clear-uffd-wp-pte-pmd-state-on-mremap +++ a/mm/mremap.c @@ -138,6 +138,7 @@ static int move_ptes(struct vm_area_stru struct vm_area_struct *new_vma, pmd_t *new_pmd, unsigned long new_addr, bool need_rmap_locks) { + bool need_clear_uffd_wp = vma_has_uffd_without_event_remap(vma); struct mm_struct *mm = vma->vm_mm; pte_t *old_pte, *new_pte, pte; pmd_t dummy_pmdval; @@ -216,7 +217,18 @@ static int move_ptes(struct vm_area_stru force_flush = true; pte = move_pte(pte, old_addr, new_addr); pte = move_soft_dirty_pte(pte); - set_pte_at(mm, new_addr, new_pte, pte); + + if (need_clear_uffd_wp && pte_marker_uffd_wp(pte)) + pte_clear(mm, new_addr, new_pte); + else { + if (need_clear_uffd_wp) { + if (pte_present(pte)) + pte = pte_clear_uffd_wp(pte); + else if (is_swap_pte(pte)) + pte = pte_swp_clear_uffd_wp(pte); + } + set_pte_at(mm, new_addr, new_pte, pte); + } } arch_leave_lazy_mmu_mode(); @@ -278,6 +290,15 @@ static bool move_normal_pmd(struct vm_ar if (WARN_ON_ONCE(!pmd_none(*new_pmd))) return false; + /* If this pmd belongs to a uffd vma with remap events disabled, we need + * to ensure that the uffd-wp state is cleared from all pgtables. This + * means recursing into lower page tables in move_page_tables(), and we + * can reuse the existing code if we simply treat the entry as "not + * moved". + */ + if (vma_has_uffd_without_event_remap(vma)) + return false; + /* * We don't have to worry about the ordering of src and dst * ptlocks because exclusive mmap_lock prevents deadlock. @@ -333,6 +354,15 @@ static bool move_normal_pud(struct vm_ar if (WARN_ON_ONCE(!pud_none(*new_pud))) return false; + /* If this pud belongs to a uffd vma with remap events disabled, we need + * to ensure that the uffd-wp state is cleared from all pgtables. This + * means recursing into lower page tables in move_page_tables(), and we + * can reuse the existing code if we simply treat the entry as "not + * moved". + */ + if (vma_has_uffd_without_event_remap(vma)) + return false; + /* * We don't have to worry about the ordering of src and dst * ptlocks because exclusive mmap_lock prevents deadlock. _ Patches currently in -mm which might be from ryan.roberts(a)arm.com are mm-clear-uffd-wp-pte-pmd-state-on-mremap.patch

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