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On 32-bit book3s with hash-MMUs, tlb_flush() was a no-op. This was
unnoticed because all uses until recently were for unmaps, and thus
handled by __tlb_remove_tlb_entry().
After commit 4a18419f71cd ("mm/mprotect: use mmu_gather") in kernel 5.19,
tlb_gather_mmu() started being used for mprotect as well. This caused
mprotect to simply not work on these machines:
int *ptr = mmap(NULL, 4096, PROT_READ|PROT_WRITE,
MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
*ptr = 1; // force HPTE to be created
mprotect(ptr, 4096, PROT_READ);
*ptr = 2; // should segfault, but succeeds
Fixed by making tlb_flush() actually flush TLB pages. This finally
agrees with the behaviour of boot3s64's tlb_flush().
Fixes: 4a18419f71cd ("mm/mprotect: use mmu_gather")
Cc: stable(a)vger.kernel.org
Reviewed-by: Christophe Leroy <christophe.leroy(a)csgroup.eu>
Reviewed-by: Ritesh Harjani (IBM) <ritesh.list(a)gmail.com>
Signed-off-by: Dave Vasilevsky <dave(a)vasilevsky.ca>
---
Changes in v3:
- Fix formatting
- Link to v2: https://lore.kernel.org/r/20251111-vasi-mprotect-g3-v2-1-881c94afbc42@vasil…
Changes in v2:
- Flush entire TLB if full mm is requested.
- Link to v1: https://lore.kernel.org/r/20251027-vasi-mprotect-g3-v1-1-3c5187085f9a@vasil…
---
arch/powerpc/include/asm/book3s/32/tlbflush.h | 5 ++++-
arch/powerpc/mm/book3s32/tlb.c | 9 +++++++++
2 files changed, 13 insertions(+), 1 deletion(-)
diff --git a/arch/powerpc/include/asm/book3s/32/tlbflush.h b/arch/powerpc/include/asm/book3s/32/tlbflush.h
index e43534da5207aa3b0cb3c07b78e29b833c141f3f..4be2200a3c7e1e8307f5ce1f1d5d28047429c106 100644
--- a/arch/powerpc/include/asm/book3s/32/tlbflush.h
+++ b/arch/powerpc/include/asm/book3s/32/tlbflush.h
@@ -11,6 +11,7 @@
void hash__flush_tlb_mm(struct mm_struct *mm);
void hash__flush_tlb_page(struct vm_area_struct *vma, unsigned long vmaddr);
void hash__flush_range(struct mm_struct *mm, unsigned long start, unsigned long end);
+void hash__flush_gather(struct mmu_gather *tlb);
#ifdef CONFIG_SMP
void _tlbie(unsigned long address);
@@ -29,7 +30,9 @@ void _tlbia(void);
static inline void tlb_flush(struct mmu_gather *tlb)
{
/* 603 needs to flush the whole TLB here since it doesn't use a hash table. */
- if (!mmu_has_feature(MMU_FTR_HPTE_TABLE))
+ if (mmu_has_feature(MMU_FTR_HPTE_TABLE))
+ hash__flush_gather(tlb);
+ else
_tlbia();
}
diff --git a/arch/powerpc/mm/book3s32/tlb.c b/arch/powerpc/mm/book3s32/tlb.c
index 9ad6b56bfec96e989b96f027d075ad5812500854..e54a7b0112322e5818d80facd2e3c7722e6dd520 100644
--- a/arch/powerpc/mm/book3s32/tlb.c
+++ b/arch/powerpc/mm/book3s32/tlb.c
@@ -105,3 +105,12 @@ void hash__flush_tlb_page(struct vm_area_struct *vma, unsigned long vmaddr)
flush_hash_pages(mm->context.id, vmaddr, pmd_val(*pmd), 1);
}
EXPORT_SYMBOL(hash__flush_tlb_page);
+
+void hash__flush_gather(struct mmu_gather *tlb)
+{
+ if (tlb->fullmm || tlb->need_flush_all)
+ hash__flush_tlb_mm(tlb->mm);
+ else
+ hash__flush_range(tlb->mm, tlb->start, tlb->end);
+}
+EXPORT_SYMBOL(hash__flush_gather);
---
base-commit: 24172e0d79900908cf5ebf366600616d29c9b417
change-id: 20251027-vasi-mprotect-g3-f8f5278d4140
Best regards,
--
Dave Vasilevsky <dave(a)vasilevsky.ca>
When of_find_net_device_by_node() successfully acquires a reference to
a network device but the subsequent call to dsa_port_parse_cpu()
fails, dsa_port_parse_of() returns without releasing the reference
count on the network device.
of_find_net_device_by_node() increments the reference count of the
returned structure, which should be balanced with a corresponding
put_device() when the reference is no longer needed.
Found by code review.
Cc: stable(a)vger.kernel.org
Fixes: 6ca80638b90c ("net: dsa: Use conduit and user terms")
Signed-off-by: Ma Ke <make24(a)iscas.ac.cn>
---
net/dsa/dsa.c | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)
diff --git a/net/dsa/dsa.c b/net/dsa/dsa.c
index 5b01a0e43ebe..632e0d716d62 100644
--- a/net/dsa/dsa.c
+++ b/net/dsa/dsa.c
@@ -1246,6 +1246,7 @@ static int dsa_port_parse_of(struct dsa_port *dp, struct device_node *dn)
struct device_node *ethernet = of_parse_phandle(dn, "ethernet", 0);
const char *name = of_get_property(dn, "label", NULL);
bool link = of_property_read_bool(dn, "link");
+ int err;
dp->dn = dn;
@@ -1259,7 +1260,13 @@ static int dsa_port_parse_of(struct dsa_port *dp, struct device_node *dn)
return -EPROBE_DEFER;
user_protocol = of_get_property(dn, "dsa-tag-protocol", NULL);
- return dsa_port_parse_cpu(dp, conduit, user_protocol);
+ err = dsa_port_parse_cpu(dp, conduit, user_protocol);
+ if (err) {
+ put_device(conduit);
+ return err;
+ }
+
+ return 0;
}
if (link)
--
2.17.1
When allocating hugetlb folios for memfd, three initialization steps
are missing:
1. Folios are not zeroed, leading to kernel memory disclosure to userspace
2. Folios are not marked uptodate before adding to page cache
3. hugetlb_fault_mutex is not taken before hugetlb_add_to_page_cache()
The memfd allocation path bypasses the normal page fault handler
(hugetlb_no_page) which would handle all of these initialization steps.
This is problematic especially for udmabuf use cases where folios are
pinned and directly accessed by userspace via DMA.
Fix by matching the initialization pattern used in hugetlb_no_page():
- Zero the folio using folio_zero_user() which is optimized for huge pages
- Mark it uptodate with folio_mark_uptodate()
- Take hugetlb_fault_mutex before adding to page cache to prevent races
The folio_zero_user() change also fixes a potential security issue where
uninitialized kernel memory could be disclosed to userspace through
read() or mmap() operations on the memfd.
Reported-by: syzbot+f64019ba229e3a5c411b(a)syzkaller.appspotmail.com
Link: https://lore.kernel.org/all/20251112031631.2315651-1-kartikey406@gmail.com/ [v1]
Closes: https://syzkaller.appspot.com/bug?extid=f64019ba229e3a5c411b
Fixes: 89c1905d9c14 ("mm/gup: introduce memfd_pin_folios() for pinning memfd folios")
Cc: stable(a)vger.kernel.org
Suggested-by: Oscar Salvador <osalvador(a)suse.de>
Suggested-by: David Hildenbrand <david(a)redhat.com>
Tested-by: syzbot+f64019ba229e3a5c411b(a)syzkaller.appspotmail.com
Signed-off-by: Deepanshu Kartikey <kartikey406(a)gmail.com>
---
v1 -> v2:
- Use folio_zero_user() instead of folio_zero_range() (optimized for huge pages)
- Add folio_mark_uptodate() before adding to page cache
- Add hugetlb_fault_mutex locking around hugetlb_add_to_page_cache()
- Add Fixes: tag and Cc: stable for backporting
- Add Suggested-by: tags for Oscar and David
---
mm/memfd.c | 27 +++++++++++++++++++++++++++
1 file changed, 27 insertions(+)
diff --git a/mm/memfd.c b/mm/memfd.c
index 1d109c1acf21..d32eef58d154 100644
--- a/mm/memfd.c
+++ b/mm/memfd.c
@@ -96,9 +96,36 @@ struct folio *memfd_alloc_folio(struct file *memfd, pgoff_t idx)
NULL,
gfp_mask);
if (folio) {
+ u32 hash;
+
+ /*
+ * Zero the folio to prevent information leaks to userspace.
+ * Use folio_zero_user() which is optimized for huge/gigantic
+ * pages. Pass 0 as addr_hint since this is not a faulting path
+ * and we don't have a user virtual address yet.
+ */
+ folio_zero_user(folio, 0);
+
+ /*
+ * Mark the folio uptodate before adding to page cache,
+ * as required by filemap.c and other hugetlb paths.
+ */
+ __folio_mark_uptodate(folio);
+
+ /*
+ * Serialize hugepage allocation and instantiation to prevent
+ * races with concurrent allocations, as required by all other
+ * callers of hugetlb_add_to_page_cache().
+ */
+ hash = hugetlb_fault_mutex_hash(memfd->f_mapping, idx);
+ mutex_lock(&hugetlb_fault_mutex_table[hash]);
+
err = hugetlb_add_to_page_cache(folio,
memfd->f_mapping,
idx);
+
+ mutex_unlock(&hugetlb_fault_mutex_table[hash]);
+
if (err) {
folio_put(folio);
goto err_unresv;
--
2.43.0
The following commit has been merged into the timers/urgent branch of tip:
Commit-ID: 20739af07383e6eb1ec59dcd70b72ebfa9ac362c
Gitweb: https://git.kernel.org/tip/20739af07383e6eb1ec59dcd70b72ebfa9ac362c
Author: Yipeng Zou <zouyipeng(a)huawei.com>
AuthorDate: Sat, 22 Nov 2025 09:39:42
Committer: Thomas Gleixner <tglx(a)linutronix.de>
CommitterDate: Sat, 22 Nov 2025 22:55:26 +01:00
timers: Fix NULL function pointer race in timer_shutdown_sync()
There is a race condition between timer_shutdown_sync() and timer
expiration that can lead to hitting a WARN_ON in expire_timers().
The issue occurs when timer_shutdown_sync() clears the timer function
to NULL while the timer is still running on another CPU. The race
scenario looks like this:
CPU0 CPU1
<SOFTIRQ>
lock_timer_base()
expire_timers()
base->running_timer = timer;
unlock_timer_base()
[call_timer_fn enter]
mod_timer()
...
timer_shutdown_sync()
lock_timer_base()
// For now, will not detach the timer but only clear its function to NULL
if (base->running_timer != timer)
ret = detach_if_pending(timer, base, true);
if (shutdown)
timer->function = NULL;
unlock_timer_base()
[call_timer_fn exit]
lock_timer_base()
base->running_timer = NULL;
unlock_timer_base()
...
// Now timer is pending while its function set to NULL.
// next timer trigger
<SOFTIRQ>
expire_timers()
WARN_ON_ONCE(!fn) // hit
...
lock_timer_base()
// Now timer will detach
if (base->running_timer != timer)
ret = detach_if_pending(timer, base, true);
if (shutdown)
timer->function = NULL;
unlock_timer_base()
The problem is that timer_shutdown_sync() clears the timer function
regardless of whether the timer is currently running. This can leave a
pending timer with a NULL function pointer, which triggers the
WARN_ON_ONCE(!fn) check in expire_timers().
Fix this by only clearing the timer function when actually detaching the
timer. If the timer is running, leave the function pointer intact, which is
safe because the timer will be properly detached when it finishes running.
Fixes: 0cc04e80458a ("timers: Add shutdown mechanism to the internal functions")
Signed-off-by: Yipeng Zou <zouyipeng(a)huawei.com>
Signed-off-by: Thomas Gleixner <tglx(a)linutronix.de>
Cc: stable(a)vger.kernel.org
Link: https://patch.msgid.link/20251122093942.301559-1-zouyipeng@huawei.com
---
kernel/time/timer.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)
diff --git a/kernel/time/timer.c b/kernel/time/timer.c
index 553fa46..d5ebb1d 100644
--- a/kernel/time/timer.c
+++ b/kernel/time/timer.c
@@ -1458,10 +1458,11 @@ static int __try_to_del_timer_sync(struct timer_list *timer, bool shutdown)
base = lock_timer_base(timer, &flags);
- if (base->running_timer != timer)
+ if (base->running_timer != timer) {
ret = detach_if_pending(timer, base, true);
- if (shutdown)
- timer->function = NULL;
+ if (shutdown)
+ timer->function = NULL;
+ }
raw_spin_unlock_irqrestore(&base->lock, flags);
Hi,
As you have been an exhibitor at “MEDICA 2025” has successfully concluded, and the final verified attendees list is now available for your post-show outreach.
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Greg Kroah-Hartman <gregkh(a)linuxfoundation.org> wrote:
> This is the start of the stable review cycle for the 6.12.58 release.
> There are 565 patches in this series, all will be posted as a response
> to this one. If anyone has any issues with these being applied, please
> let me know.
[SNIP]
> Zizhi Wo <wozizhi(a)huaweicloud.com>
> tty/vt: Add missing return value for VT_RESIZE in vt_ioctl()
Locking seems to be messed up in backport of above mentioned patch.
That patch is viewable here:
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable-rc.git/…
Upstream uses guard() locking:
| case VT_RESIZE:
| {
| ....
| guard(console_lock)();
| ^^^^^^^^^^^^^^^^^^^^^-------this generates auto-unlock code
| ....
| ret = __vc_resize(vc_cons[i].d, cc, ll, true);
| if (ret)
| return ret;
| ^^^^^^^^^^----------this releases console lock
| ....
| break;
| }
Older stable branches use old-school locking:
| case VT_RESIZE:
| {
| ....
| console_lock();
| ....
| ret = __vc_resize(vc_cons[i].d, cc, ll, true);
| if (ret)
| return ret;
| ^^^^^^^^^^----------this does not release console lock
| ....
| console_unlock();
| break;
| }
Backporting upstream fixes that use guard() locking to older stable
branches that use old-school locking need "extra sports".
Please consider dropping or fixing above mentioned patch.
--
Jari Ruusu 4096R/8132F189 12D6 4C3A DCDA 0AA4 27BD ACDF F073 3C80 8132 F189
The patch below does not apply to the 6.17-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable(a)vger.kernel.org>.
To reproduce the conflict and resubmit, you may use the following commands:
git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.17.y
git checkout FETCH_HEAD
git cherry-pick -x a2fff99f92dae9c0eaf0d75de3def70ec68dad92
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2025112136-panama-nape-342b@gregkh' --subject-prefix 'PATCH 6.17.y' HEAD^..
Possible dependencies:
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From a2fff99f92dae9c0eaf0d75de3def70ec68dad92 Mon Sep 17 00:00:00 2001
From: Pasha Tatashin <pasha.tatashin(a)soleen.com>
Date: Mon, 20 Oct 2025 20:08:51 -0400
Subject: [PATCH] kho: increase metadata bitmap size to PAGE_SIZE
KHO memory preservation metadata is preserved in 512 byte chunks which
requires their allocation from slab allocator. Slabs are not safe to be
used with KHO because of kfence, and because partial slabs may lead leaks
to the next kernel. Change the size to be PAGE_SIZE.
The kfence specifically may cause memory corruption, where it randomly
provides slab objects that can be within the scratch area. The reason for
that is that kfence allocates its objects prior to KHO scratch is marked
as CMA region.
While this change could potentially increase metadata overhead on systems
with sparsely preserved memory, this is being mitigated by ongoing work to
reduce sparseness during preservation via 1G guest pages. Furthermore,
this change aligns with future work on a stateless KHO, which will also
use page-sized bitmaps for its radix tree metadata.
Link: https://lkml.kernel.org/r/20251021000852.2924827-3-pasha.tatashin@soleen.com
Fixes: fc33e4b44b27 ("kexec: enable KHO support for memory preservation")
Signed-off-by: Pasha Tatashin <pasha.tatashin(a)soleen.com>
Reviewed-by: Mike Rapoport (Microsoft) <rppt(a)kernel.org>
Reviewed-by: Pratyush Yadav <pratyush(a)kernel.org>
Cc: Alexander Graf <graf(a)amazon.com>
Cc: Christian Brauner <brauner(a)kernel.org>
Cc: David Matlack <dmatlack(a)google.com>
Cc: Jason Gunthorpe <jgg(a)ziepe.ca>
Cc: Jonathan Corbet <corbet(a)lwn.net>
Cc: Masahiro Yamada <masahiroy(a)kernel.org>
Cc: Miguel Ojeda <ojeda(a)kernel.org>
Cc: Randy Dunlap <rdunlap(a)infradead.org>
Cc: Samiullah Khawaja <skhawaja(a)google.com>
Cc: Tejun Heo <tj(a)kernel.org>
Cc: <stable(a)vger.kernel.org>
Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org>
diff --git a/kernel/kexec_handover.c b/kernel/kexec_handover.c
index 0bc9001e532a..9217d2fdd2d3 100644
--- a/kernel/kexec_handover.c
+++ b/kernel/kexec_handover.c
@@ -69,10 +69,10 @@ early_param("kho", kho_parse_enable);
* Keep track of memory that is to be preserved across KHO.
*
* The serializing side uses two levels of xarrays to manage chunks of per-order
- * 512 byte bitmaps. For instance if PAGE_SIZE = 4096, the entire 1G order of a
- * 1TB system would fit inside a single 512 byte bitmap. For order 0 allocations
- * each bitmap will cover 16M of address space. Thus, for 16G of memory at most
- * 512K of bitmap memory will be needed for order 0.
+ * PAGE_SIZE byte bitmaps. For instance if PAGE_SIZE = 4096, the entire 1G order
+ * of a 8TB system would fit inside a single 4096 byte bitmap. For order 0
+ * allocations each bitmap will cover 128M of address space. Thus, for 16G of
+ * memory at most 512K of bitmap memory will be needed for order 0.
*
* This approach is fully incremental, as the serialization progresses folios
* can continue be aggregated to the tracker. The final step, immediately prior
@@ -80,12 +80,14 @@ early_param("kho", kho_parse_enable);
* successor kernel to parse.
*/
-#define PRESERVE_BITS (512 * 8)
+#define PRESERVE_BITS (PAGE_SIZE * 8)
struct kho_mem_phys_bits {
DECLARE_BITMAP(preserve, PRESERVE_BITS);
};
+static_assert(sizeof(struct kho_mem_phys_bits) == PAGE_SIZE);
+
struct kho_mem_phys {
/*
* Points to kho_mem_phys_bits, a sparse bitmap array. Each bit is sized
@@ -133,19 +135,19 @@ static struct kho_out kho_out = {
.finalized = false,
};
-static void *xa_load_or_alloc(struct xarray *xa, unsigned long index, size_t sz)
+static void *xa_load_or_alloc(struct xarray *xa, unsigned long index)
{
void *res = xa_load(xa, index);
if (res)
return res;
- void *elm __free(kfree) = kzalloc(sz, GFP_KERNEL);
+ void *elm __free(kfree) = kzalloc(PAGE_SIZE, GFP_KERNEL);
if (!elm)
return ERR_PTR(-ENOMEM);
- if (WARN_ON(kho_scratch_overlap(virt_to_phys(elm), sz)))
+ if (WARN_ON(kho_scratch_overlap(virt_to_phys(elm), PAGE_SIZE)))
return ERR_PTR(-EINVAL);
res = xa_cmpxchg(xa, index, NULL, elm, GFP_KERNEL);
@@ -218,8 +220,7 @@ static int __kho_preserve_order(struct kho_mem_track *track, unsigned long pfn,
}
}
- bits = xa_load_or_alloc(&physxa->phys_bits, pfn_high / PRESERVE_BITS,
- sizeof(*bits));
+ bits = xa_load_or_alloc(&physxa->phys_bits, pfn_high / PRESERVE_BITS);
if (IS_ERR(bits))
return PTR_ERR(bits);