- Linux-stable-mirror - lists.linaro.org

[PATCH 1/8] drm/sched: Add locking to drm_sched_entity_modify_sched

by Tvrtko Ursulin

From: Tvrtko Ursulin <tvrtko.ursulin(a)igalia.com> Without the locking amdgpu currently can race between amdgpu_ctx_set_entity_priority() (via drm_sched_entity_modify_sched()) and drm_sched_job_arm(), leading to the latter accesing potentially inconsitent entity->sched_list and entity->num_sched_list pair. v2: * Improve commit message. (Philipp) Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin(a)igalia.com> Fixes: b37aced31eb0 ("drm/scheduler: implement a function to modify sched list") Cc: Christian König <christian.koenig(a)amd.com> Cc: Alex Deucher <alexander.deucher(a)amd.com> Cc: Luben Tuikov <ltuikov89(a)gmail.com> Cc: Matthew Brost <matthew.brost(a)intel.com> Cc: David Airlie <airlied(a)gmail.com> Cc: Daniel Vetter <daniel(a)ffwll.ch> Cc: dri-devel(a)lists.freedesktop.org Cc: Philipp Stanner <pstanner(a)redhat.com> Cc: <stable(a)vger.kernel.org> # v5.7+ Reviewed-by: Christian König <christian.koenig(a)amd.com> --- drivers/gpu/drm/scheduler/sched_entity.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/gpu/drm/scheduler/sched_entity.c b/drivers/gpu/drm/scheduler/sched_entity.c index 567e5ace6d0c..0e002c17fcb6 100644 --- a/drivers/gpu/drm/scheduler/sched_entity.c +++ b/drivers/gpu/drm/scheduler/sched_entity.c @@ -133,8 +133,10 @@ void drm_sched_entity_modify_sched(struct drm_sched_entity *entity, { WARN_ON(!num_sched_list || !sched_list); + spin_lock(&entity->rq_lock); entity->sched_list = sched_list; entity->num_sched_list = num_sched_list; + spin_unlock(&entity->rq_lock); } EXPORT_SYMBOL(drm_sched_entity_modify_sched); -- 2.46.0

11 months, 3 weeks

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[PATCH v3] mac802154: Fix potential RCU dereference issue in mac802154_scan_worker

by Jiawei Ye

In the `mac802154_scan_worker` function, the `scan_req->type` field was accessed after the RCU read-side critical section was unlocked. According to RCU usage rules, this is illegal and can lead to unpredictable behavior, such as accessing memory that has been updated or causing use-after-free issues. This possible bug was identified using a static analysis tool developed by myself, specifically designed to detect RCU-related issues. To address this, the `scan_req->type` value is now stored in a local variable `scan_req_type` while still within the RCU read-side critical section. The `scan_req_type` is then used after the RCU lock is released, ensuring that the type value is safely accessed without violating RCU rules. Fixes: e2c3e6f53a7a ("mac802154: Handle active scanning") Cc: stable(a)vger.kernel.org Signed-off-by: Jiawei Ye <jiawei.ye(a)foxmail.com> Acked-by: Miquel Raynal <miquel.raynal(a)bootlin.com> --- Changelog: v1 -> v2: - Repositioned the enum nl802154_scan_types scan_req_type declaration between struct cfg802154_scan_request *scan_req and struct ieee802154_sub_if_data *sdata to comply with the reverse Christmas tree rule. v2 -> v3: - Add Cc stable tag and Acked-by. --- net/mac802154/scan.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/net/mac802154/scan.c b/net/mac802154/scan.c index 1c0eeaa76560..a6dab3cc3ad8 100644 --- a/net/mac802154/scan.c +++ b/net/mac802154/scan.c @@ -176,6 +176,7 @@ void mac802154_scan_worker(struct work_struct *work) struct ieee802154_local *local = container_of(work, struct ieee802154_local, scan_work.work); struct cfg802154_scan_request *scan_req; + enum nl802154_scan_types scan_req_type; struct ieee802154_sub_if_data *sdata; unsigned int scan_duration = 0; struct wpan_phy *wpan_phy; @@ -209,6 +210,7 @@ void mac802154_scan_worker(struct work_struct *work) } wpan_phy = scan_req->wpan_phy; + scan_req_type = scan_req->type; scan_req_duration = scan_req->duration; /* Look for the next valid chan */ @@ -246,7 +248,7 @@ void mac802154_scan_worker(struct work_struct *work) goto end_scan; } - if (scan_req->type == NL802154_SCAN_ACTIVE) { + if (scan_req_type == NL802154_SCAN_ACTIVE) { ret = mac802154_transmit_beacon_req(local, sdata); if (ret) dev_err(&sdata->dev->dev, -- 2.34.1

11 months, 3 weeks

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[PATCH v6 2/3] x86/sgx: Resolve EAUG race where losing thread returns SIGBUS

by Dmitrii Kuvaiskii

Imagine an mmap()'d file. Two threads touch the same address at the same time and fault. Both allocate a physical page and race to install a PTE for that page. Only one will win the race. The loser frees its page, but still continues handling the fault as a success and returns VM_FAULT_NOPAGE from the fault handler. The same race can happen with SGX. But there's a bug: the loser in the SGX steers into a failure path. The loser EREMOVE's the winner's EPC page, then returns SIGBUS, likely killing the app. Fix the SGX loser's behavior. Check whether another thread already allocated the page and if yes, return with VM_FAULT_NOPAGE. The race can be illustrated as follows: /* /* * Fault on CPU1 * Fault on CPU2 * on enclave page X * on enclave page X */ */ sgx_vma_fault() { sgx_vma_fault() { xa_load(&encl->page_array) xa_load(&encl->page_array) == NULL --> == NULL --> sgx_encl_eaug_page() { sgx_encl_eaug_page() { ... ... /* /* * alloc encl_page * alloc encl_page */ */ mutex_lock(&encl->lock); /* * alloc EPC page */ epc_page = sgx_alloc_epc_page(...); /* * add page to enclave's xarray */ xa_insert(&encl->page_array, ...); /* * add page to enclave via EAUG * (page is in pending state) */ /* * add PTE entry */ vmf_insert_pfn(...); mutex_unlock(&encl->lock); return VM_FAULT_NOPAGE; } } /* * All good up to here: enclave page * successfully added to enclave, * ready for EACCEPT from user space */ mutex_lock(&encl->lock); /* * alloc EPC page */ epc_page = sgx_alloc_epc_page(...); /* * add page to enclave's xarray, * this fails with -EBUSY as this * page was already added by CPU2 */ xa_insert(&encl->page_array, ...); err_out_shrink: sgx_encl_free_epc_page(epc_page) { /* * remove page via EREMOVE * * *BUG*: page added by CPU2 is * yanked from enclave while it * remains accessible from OS * perspective (PTE installed) */ /* * free EPC page */ sgx_free_epc_page(epc_page); } mutex_unlock(&encl->lock); /* * *BUG*: SIGBUS is returned * for a valid enclave page */ return VM_FAULT_SIGBUS; } } Fixes: 5a90d2c3f5ef ("x86/sgx: Support adding of pages to an initialized enclave") Cc: stable(a)vger.kernel.org Reported-by: Marcelina Kościelnicka <mwk(a)invisiblethingslab.com> Suggested-by: Kai Huang <kai.huang(a)intel.com> Reviewed-by: Kai Huang <kai.huang(a)intel.com> Reviewed-by: Jarkko Sakkinen <jarkko(a)kernel.org> Signed-off-by: Dmitrii Kuvaiskii <dmitrii.kuvaiskii(a)intel.com> --- arch/x86/kernel/cpu/sgx/encl.c | 36 ++++++++++++++++++++-------------- 1 file changed, 21 insertions(+), 15 deletions(-) diff --git a/arch/x86/kernel/cpu/sgx/encl.c b/arch/x86/kernel/cpu/sgx/encl.c index c0a3c00284c8..2aa7ced0e4a0 100644 --- a/arch/x86/kernel/cpu/sgx/encl.c +++ b/arch/x86/kernel/cpu/sgx/encl.c @@ -337,6 +337,16 @@ static vm_fault_t sgx_encl_eaug_page(struct vm_area_struct *vma, if (!test_bit(SGX_ENCL_INITIALIZED, &encl->flags)) return VM_FAULT_SIGBUS; + mutex_lock(&encl->lock); + + /* + * Multiple threads may try to fault on the same page concurrently. + * Re-check if another thread has already done that. + */ + encl_page = xa_load(&encl->page_array, PFN_DOWN(addr)); + if (encl_page) + goto done; + /* * Ignore internal permission checking for dynamically added pages. * They matter only for data added during the pre-initialization @@ -345,23 +355,23 @@ static vm_fault_t sgx_encl_eaug_page(struct vm_area_struct *vma, */ secinfo_flags = SGX_SECINFO_R | SGX_SECINFO_W | SGX_SECINFO_X; encl_page = sgx_encl_page_alloc(encl, addr - encl->base, secinfo_flags); - if (IS_ERR(encl_page)) - return VM_FAULT_OOM; - - mutex_lock(&encl->lock); + if (IS_ERR(encl_page)) { + vmret = VM_FAULT_OOM; + goto err_out_unlock; + } epc_page = sgx_encl_load_secs(encl); if (IS_ERR(epc_page)) { if (PTR_ERR(epc_page) == -EBUSY) vmret = VM_FAULT_NOPAGE; - goto err_out_unlock; + goto err_out_encl; } epc_page = sgx_alloc_epc_page(encl_page, false); if (IS_ERR(epc_page)) { if (PTR_ERR(epc_page) == -EBUSY) vmret = VM_FAULT_NOPAGE; - goto err_out_unlock; + goto err_out_encl; } va_page = sgx_encl_grow(encl, false); @@ -376,10 +386,6 @@ static vm_fault_t sgx_encl_eaug_page(struct vm_area_struct *vma, ret = xa_insert(&encl->page_array, PFN_DOWN(encl_page->desc), encl_page, GFP_KERNEL); - /* - * If ret == -EBUSY then page was created in another flow while - * running without encl->lock - */ if (ret) goto err_out_shrink; @@ -389,7 +395,7 @@ static vm_fault_t sgx_encl_eaug_page(struct vm_area_struct *vma, ret = __eaug(&pginfo, sgx_get_epc_virt_addr(epc_page)); if (ret) - goto err_out; + goto err_out_eaug; encl_page->encl = encl; encl_page->epc_page = epc_page; @@ -408,20 +414,20 @@ static vm_fault_t sgx_encl_eaug_page(struct vm_area_struct *vma, mutex_unlock(&encl->lock); return VM_FAULT_SIGBUS; } +done: mutex_unlock(&encl->lock); return VM_FAULT_NOPAGE; -err_out: +err_out_eaug: xa_erase(&encl->page_array, PFN_DOWN(encl_page->desc)); - err_out_shrink: sgx_encl_shrink(encl, va_page); err_out_epc: sgx_encl_free_epc_page(epc_page); +err_out_encl: + kfree(encl_page); err_out_unlock: mutex_unlock(&encl->lock); - kfree(encl_page); - return vmret; } -- 2.43.0

11 months, 3 weeks

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[PATCH v6 1/3] x86/sgx: Split SGX_ENCL_PAGE_BEING_RECLAIMED into two flags

by Dmitrii Kuvaiskii

The page reclaimer thread sets SGX_ENC_PAGE_BEING_RECLAIMED flag when the enclave page is being reclaimed (moved to the backing store). This flag however has two logical meanings: 1. Don't attempt to load the enclave page (the page is busy), see __sgx_encl_load_page(). 2. Don't attempt to remove the PCMD page corresponding to this enclave page (the PCMD page is busy), see reclaimer_writing_to_pcmd(). To reflect these two meanings, split SGX_ENCL_PAGE_BEING_RECLAIMED into two flags: SGX_ENCL_PAGE_BUSY and SGX_ENCL_PAGE_PCMD_BUSY. Currently, both flags are set only when the enclave page is being reclaimed (by the page reclaimer thread). A future commit will introduce new cases when the enclave page is being operated on; these new cases will set only the SGX_ENCL_PAGE_BUSY flag. Cc: stable(a)vger.kernel.org Signed-off-by: Dmitrii Kuvaiskii <dmitrii.kuvaiskii(a)intel.com> Reviewed-by: Haitao Huang <haitao.huang(a)linux.intel.com> Reviewed-by: Jarkko Sakkinen <jarkko(a)kernel.org> Acked-by: Kai Huang <kai.huang(a)intel.com> --- arch/x86/kernel/cpu/sgx/encl.c | 16 +++++++--------- arch/x86/kernel/cpu/sgx/encl.h | 10 ++++++++-- arch/x86/kernel/cpu/sgx/main.c | 4 ++-- 3 files changed, 17 insertions(+), 13 deletions(-) diff --git a/arch/x86/kernel/cpu/sgx/encl.c b/arch/x86/kernel/cpu/sgx/encl.c index 279148e72459..c0a3c00284c8 100644 --- a/arch/x86/kernel/cpu/sgx/encl.c +++ b/arch/x86/kernel/cpu/sgx/encl.c @@ -46,10 +46,10 @@ static int sgx_encl_lookup_backing(struct sgx_encl *encl, unsigned long page_ind * a check if an enclave page sharing the PCMD page is in the process of being * reclaimed. * - * The reclaimer sets the SGX_ENCL_PAGE_BEING_RECLAIMED flag when it - * intends to reclaim that enclave page - it means that the PCMD page - * associated with that enclave page is about to get some data and thus - * even if the PCMD page is empty, it should not be truncated. + * The reclaimer sets the SGX_ENCL_PAGE_PCMD_BUSY flag when it intends to + * reclaim that enclave page - it means that the PCMD page associated with that + * enclave page is about to get some data and thus even if the PCMD page is + * empty, it should not be truncated. * * Context: Enclave mutex (&sgx_encl->lock) must be held. * Return: 1 if the reclaimer is about to write to the PCMD page @@ -77,8 +77,7 @@ static int reclaimer_writing_to_pcmd(struct sgx_encl *encl, * Stop when reaching the SECS page - it does not * have a page_array entry and its reclaim is * started and completed with enclave mutex held so - * it does not use the SGX_ENCL_PAGE_BEING_RECLAIMED - * flag. + * it does not use the SGX_ENCL_PAGE_PCMD_BUSY flag. */ if (addr == encl->base + encl->size) break; @@ -91,8 +90,7 @@ static int reclaimer_writing_to_pcmd(struct sgx_encl *encl, * VA page slot ID uses same bit as the flag so it is important * to ensure that the page is not already in backing store. */ - if (entry->epc_page && - (entry->desc & SGX_ENCL_PAGE_BEING_RECLAIMED)) { + if (entry->epc_page && (entry->desc & SGX_ENCL_PAGE_PCMD_BUSY)) { reclaimed = 1; break; } @@ -257,7 +255,7 @@ static struct sgx_encl_page *__sgx_encl_load_page(struct sgx_encl *encl, /* Entry successfully located. */ if (entry->epc_page) { - if (entry->desc & SGX_ENCL_PAGE_BEING_RECLAIMED) + if (entry->desc & SGX_ENCL_PAGE_BUSY) return ERR_PTR(-EBUSY); return entry; diff --git a/arch/x86/kernel/cpu/sgx/encl.h b/arch/x86/kernel/cpu/sgx/encl.h index f94ff14c9486..b566b8ad5f33 100644 --- a/arch/x86/kernel/cpu/sgx/encl.h +++ b/arch/x86/kernel/cpu/sgx/encl.h @@ -22,8 +22,14 @@ /* 'desc' bits holding the offset in the VA (version array) page. */ #define SGX_ENCL_PAGE_VA_OFFSET_MASK GENMASK_ULL(11, 3) -/* 'desc' bit marking that the page is being reclaimed. */ -#define SGX_ENCL_PAGE_BEING_RECLAIMED BIT(3) +/* 'desc' bit indicating that the page is busy (being reclaimed). */ +#define SGX_ENCL_PAGE_BUSY BIT(2) + +/* + * 'desc' bit indicating that PCMD page associated with the enclave page is + * busy (because the enclave page is being reclaimed). + */ +#define SGX_ENCL_PAGE_PCMD_BUSY BIT(3) struct sgx_encl_page { unsigned long desc; diff --git a/arch/x86/kernel/cpu/sgx/main.c b/arch/x86/kernel/cpu/sgx/main.c index f3f1461273ee..da59f034b769 100644 --- a/arch/x86/kernel/cpu/sgx/main.c +++ b/arch/x86/kernel/cpu/sgx/main.c @@ -205,7 +205,7 @@ static void sgx_encl_ewb(struct sgx_epc_page *epc_page, void *va_slot; int ret; - encl_page->desc &= ~SGX_ENCL_PAGE_BEING_RECLAIMED; + encl_page->desc &= ~(SGX_ENCL_PAGE_BUSY | SGX_ENCL_PAGE_PCMD_BUSY); va_page = list_first_entry(&encl->va_pages, struct sgx_va_page, list); @@ -341,7 +341,7 @@ static void sgx_reclaim_pages(void) goto skip; } - encl_page->desc |= SGX_ENCL_PAGE_BEING_RECLAIMED; + encl_page->desc |= SGX_ENCL_PAGE_BUSY | SGX_ENCL_PAGE_PCMD_BUSY; mutex_unlock(&encl_page->encl->lock); continue; -- 2.43.0

11 months, 3 weeks

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[PATCH] sched/fair: Fix integer underflow

by Pierre Gondois

(struct sg_lb_stats).idle_cpus is of type 'unsigned int'. (local->idle_cpus - busiest->idle_cpus) can underflow to UINT_MAX for instance, and max_t(long, 0, UINT_MAX) will output UINT_MAX. Use lsub_positive() instead of max_t(). Fixes: 0b0695f2b34a ("sched/fair: Rework load_balance()") cc: stable(a)vger.kernel.org Signed-off-by: Pierre Gondois <pierre.gondois(a)arm.com> --- kernel/sched/fair.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 9057584ec06d..6d9124499f52 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -10775,8 +10775,8 @@ static inline void calculate_imbalance(struct lb_env *env, struct sd_lb_stats *s * idle CPUs. */ env->migration_type = migrate_task; - env->imbalance = max_t(long, 0, - (local->idle_cpus - busiest->idle_cpus)); + env->imbalance = local->idle_cpus; + lsub_positive(&env->imbalance, busiest->idle_cpus); } #ifdef CONFIG_NUMA -- 2.25.1

11 months, 3 weeks

2
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[PATCHv2] usb: yurex: make waiting on yurex_write interruptible

by Oliver Neukum

The IO yurex_write() needs to wait for in order to have a device ready for writing again can take a long time time. Consequently the sleep is done in an interruptible state. Therefore others waiting for yurex_write() itself to finish should use mutex_lock_interruptible. Signed-off-by: Oliver Neukum <oneukum(a)suse.com> Fixes: 6bc235a2e24a5 ("USB: add driver for Meywa-Denki & Kayac YUREX") --- v2: fix uninitialized variable drivers/usb/misc/iowarrior.c | 4 ---- drivers/usb/misc/yurex.c | 5 ++++- 2 files changed, 4 insertions(+), 5 deletions(-) diff --git a/drivers/usb/misc/iowarrior.c b/drivers/usb/misc/iowarrior.c index cfc985001e5b..65cc53431976 100644 --- a/drivers/usb/misc/iowarrior.c +++ b/drivers/usb/misc/iowarrior.c @@ -892,7 +892,6 @@ static int iowarrior_probe(struct usb_interface *interface, static void iowarrior_disconnect(struct usb_interface *interface) { struct iowarrior *dev = usb_get_intfdata(interface); - int minor = dev->minor; usb_deregister_dev(interface, &iowarrior_class); @@ -916,9 +915,6 @@ static void iowarrior_disconnect(struct usb_interface *interface) mutex_unlock(&dev->mutex); iowarrior_delete(dev); } - - dev_info(&interface->dev, "I/O-Warror #%d now disconnected\n", - minor - IOWARRIOR_MINOR_BASE); } /* usb specific object needed to register this driver with the usb subsystem */ diff --git a/drivers/usb/misc/yurex.c b/drivers/usb/misc/yurex.c index 4a9859e03f6b..316634f782c6 100644 --- a/drivers/usb/misc/yurex.c +++ b/drivers/usb/misc/yurex.c @@ -444,7 +444,10 @@ static ssize_t yurex_write(struct file *file, const char __user *user_buffer, if (count == 0) goto error; - mutex_lock(&dev->io_mutex); + retval = mutex_lock_interruptible(&dev->io_mutex); + if (retval < 0) + return -EINTR; + if (dev->disconnected) { /* already disconnected */ mutex_unlock(&dev->io_mutex); retval = -ENODEV; -- 2.46.1

11 months, 3 weeks

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[PATCH] drm/sti: avoid potential dereference of error pointers in sti_hqvdp_atomic_check

by Ma Ke

The return value of drm_atomic_get_crtc_state() needs to be checked. To avoid use of error pointer 'crtc_state' in case of the failure. Cc: stable(a)vger.kernel.org Fixes: dd86dc2f9ae1 ("drm/sti: implement atomic_check for the planes") Signed-off-by: Ma Ke <make24(a)iscas.ac.cn> --- drivers/gpu/drm/sti/sti_hqvdp.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/gpu/drm/sti/sti_hqvdp.c b/drivers/gpu/drm/sti/sti_hqvdp.c index 0fb48ac044d8..abab92df78bd 100644 --- a/drivers/gpu/drm/sti/sti_hqvdp.c +++ b/drivers/gpu/drm/sti/sti_hqvdp.c @@ -1037,6 +1037,9 @@ static int sti_hqvdp_atomic_check(struct drm_plane *drm_plane, return 0; crtc_state = drm_atomic_get_crtc_state(state, crtc); + if (IS_ERR(crtc_state)) + return PTR_ERR(crtc_state); + mode = &crtc_state->mode; dst_x = new_plane_state->crtc_x; dst_y = new_plane_state->crtc_y; -- 2.25.1

11 months, 3 weeks

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[PATCH v2] drm/sti: avoid potential dereference of error pointers

by Ma Ke

The return value of drm_atomic_get_crtc_state() needs to be checked. To avoid use of error pointer 'crtc_state' in case of the failure. Cc: stable(a)vger.kernel.org Fixes: dd86dc2f9ae1 ("drm/sti: implement atomic_check for the planes") Signed-off-by: Ma Ke <make24(a)iscas.ac.cn> --- Changes in v2: - modified the Fixes tag according to suggestions; - added necessary blank line. --- drivers/gpu/drm/sti/sti_cursor.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/gpu/drm/sti/sti_cursor.c b/drivers/gpu/drm/sti/sti_cursor.c index db0a1eb53532..c59fcb4dca32 100644 --- a/drivers/gpu/drm/sti/sti_cursor.c +++ b/drivers/gpu/drm/sti/sti_cursor.c @@ -200,6 +200,9 @@ static int sti_cursor_atomic_check(struct drm_plane *drm_plane, return 0; crtc_state = drm_atomic_get_crtc_state(state, crtc); + if (IS_ERR(crtc_state)) + return PTR_ERR(crtc_state); + mode = &crtc_state->mode; dst_x = new_plane_state->crtc_x; dst_y = new_plane_state->crtc_y; -- 2.25.1

11 months, 3 weeks

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[PATCH RESEND] drm/sti: avoid potential dereference of error pointers in sti_gdp_atomic_check

by Ma Ke

The return value of drm_atomic_get_crtc_state() needs to be checked. To avoid use of error pointer 'crtc_state' in case of the failure. Cc: stable(a)vger.kernel.org Fixes: dd86dc2f9ae1 ("drm/sti: implement atomic_check for the planes") Signed-off-by: Ma Ke <make24(a)iscas.ac.cn> --- drivers/gpu/drm/sti/sti_gdp.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/gpu/drm/sti/sti_gdp.c b/drivers/gpu/drm/sti/sti_gdp.c index 43c72c2604a0..f046f5f7ad25 100644 --- a/drivers/gpu/drm/sti/sti_gdp.c +++ b/drivers/gpu/drm/sti/sti_gdp.c @@ -638,6 +638,9 @@ static int sti_gdp_atomic_check(struct drm_plane *drm_plane, mixer = to_sti_mixer(crtc); crtc_state = drm_atomic_get_crtc_state(state, crtc); + if (IS_ERR(crtc_state)) + return PTR_ERR(crtc_state); + mode = &crtc_state->mode; dst_x = new_plane_state->crtc_x; dst_y = new_plane_state->crtc_y; -- 2.25.1

11 months, 3 weeks

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[PATCH] mm: migrate: fix data-race in migrate_folio_unmap()

by Jeongjun Park

I found a report from syzbot [1] When __folio_test_movable() is called in migrate_folio_unmap() to read folio->mapping, a data race occurs because the folio is read without protecting it with folio_lock. This can cause unintended behavior because folio->mapping is initialized to a NULL value. Therefore, I think it is appropriate to call __folio_test_movable() under the protection of folio_lock to prevent data-race. [1] ================================================================== BUG: KCSAN: data-race in __filemap_remove_folio / migrate_pages_batch write to 0xffffea0004b81dd8 of 8 bytes by task 6348 on cpu 0: page_cache_delete mm/filemap.c:153 [inline] __filemap_remove_folio+0x1ac/0x2c0 mm/filemap.c:233 filemap_remove_folio+0x6b/0x1f0 mm/filemap.c:265 truncate_inode_folio+0x42/0x50 mm/truncate.c:178 shmem_undo_range+0x25b/0xa70 mm/shmem.c:1028 shmem_truncate_range mm/shmem.c:1144 [inline] shmem_evict_inode+0x14d/0x530 mm/shmem.c:1272 evict+0x2f0/0x580 fs/inode.c:731 iput_final fs/inode.c:1883 [inline] iput+0x42a/0x5b0 fs/inode.c:1909 dentry_unlink_inode+0x24f/0x260 fs/dcache.c:412 __dentry_kill+0x18b/0x4c0 fs/dcache.c:615 dput+0x5c/0xd0 fs/dcache.c:857 __fput+0x3fb/0x6d0 fs/file_table.c:439 ____fput+0x1c/0x30 fs/file_table.c:459 task_work_run+0x13a/0x1a0 kernel/task_work.c:228 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline] exit_to_user_mode_loop kernel/entry/common.c:114 [inline] exit_to_user_mode_prepare include/linux/entry-common.h:328 [inline] __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline] syscall_exit_to_user_mode+0xbe/0x130 kernel/entry/common.c:218 do_syscall_64+0xd6/0x1c0 arch/x86/entry/common.c:89 entry_SYSCALL_64_after_hwframe+0x77/0x7f read to 0xffffea0004b81dd8 of 8 bytes by task 6342 on cpu 1: __folio_test_movable include/linux/page-flags.h:699 [inline] migrate_folio_unmap mm/migrate.c:1199 [inline] migrate_pages_batch+0x24c/0x1940 mm/migrate.c:1797 migrate_pages_sync mm/migrate.c:1963 [inline] migrate_pages+0xff1/0x1820 mm/migrate.c:2072 do_mbind mm/mempolicy.c:1390 [inline] kernel_mbind mm/mempolicy.c:1533 [inline] __do_sys_mbind mm/mempolicy.c:1607 [inline] __se_sys_mbind+0xf76/0x1160 mm/mempolicy.c:1603 __x64_sys_mbind+0x78/0x90 mm/mempolicy.c:1603 x64_sys_call+0x2b4d/0x2d60 arch/x86/include/generated/asm/syscalls_64.h:238 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xc9/0x1c0 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f value changed: 0xffff888127601078 -> 0x0000000000000000 Reported-by: syzbot <syzkaller(a)googlegroups.com> Cc: stable(a)vger.kernel.org Fixes: 7e2a5e5ab217 ("mm: migrate: use __folio_test_movable()") Signed-off-by: Jeongjun Park <aha310510(a)gmail.com> --- mm/migrate.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/mm/migrate.c b/mm/migrate.c index 923ea80ba744..e62dac12406b 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -1118,7 +1118,7 @@ static int migrate_folio_unmap(new_folio_t get_new_folio, int rc = -EAGAIN; int old_page_state = 0; struct anon_vma *anon_vma = NULL; - bool is_lru = !__folio_test_movable(src); + bool is_lru; bool locked = false; bool dst_locked = false; @@ -1172,6 +1172,7 @@ static int migrate_folio_unmap(new_folio_t get_new_folio, locked = true; if (folio_test_mlocked(src)) old_page_state |= PAGE_WAS_MLOCKED; + is_lru = !__folio_test_movable(src); if (folio_test_writeback(src)) { /* --

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