Use-after-free

HIGH
torvalds/linux
Commit: 71d9e1561aab
Affected: Pre-7.0-rc6 (before this commit); fixed in v7.0-rc6 and newer
2026-05-25 23:46 UTC

Description

This commit bundle hardens several DRM memory-management and buffer-export paths, addressing use-after-free (UAF) and memory-safety issues observed in previous code paths. Key changes include: 1) AMDXDNA: prevent exporting private buffers via DMA-Buf by adding a private_buffer flag and returning -EOPNOTSUPP if an export is attempted on such buffers, reducing the risk of leaking internal buffers or lifetimes. 2) DRM GEM LRU/locking refactor: replace per-LRU locks with a device-wide gem_lru_mutex to guard LRU manipulations, reducing races that could lead to use-after-free or premature object reuse. 3) V3D: fix UAF in error-code paths and ensure proper GEM object reference handling on error. 4) Misc driver hardening and cleanup (bridge reset GPIO handling, IRQ cleanup paths, etc.). Overall, the fixes target use-after-free and memory-safety vulnerabilities in the DRM/GEM stack rather than a simple dependency bump or test-only change.

Commit Details

Author: Dave Airlie

Date: 2026-05-21 21:00 UTC

Message:

Merge tag 'drm-misc-fixes-2026-05-21' of https://gitlab.freedesktop.org/drm/misc/kernel into drm-fixes Short summary of fixes pull: amdxdna: - remove mmap and export for ubuf bridge: - chipone-icn6211: managed bridge cleanup - lt66121: acquire reset GPIO - megachips: fix clean up on failed IRQ requests gem: - clean up LRU locking v3d: - fix UAF in error code paths - release GEM-object ref on free'd jobs virtio: - use uninterruptible resv locking in plane updates Signed-off-by: Dave Airlie <airlied@redhat.com> From: Thomas Zimmermann <tzimmermann@suse.de> Link: https://patch.msgid.link/20260521071456.GA14644@localhost.localdomain

Triage Assessment

Vulnerability Type: Use-after-free

Confidence: HIGH

Reasoning:

The patchset includes explicit fixes related to memory safety issues (notably ‘v3d: fix UAF in error code paths’ and related GEM/object handling changes) and changes that restrict exporting certain buffers (e.g., amdxdna: abort export for private buffers). These are classic security-relevant fixes (memory safety and reduced information exposure). While some changes are broader maintenance, the presence of explicit UAF and export-control fixes indicate a security-focused fixset.

Verification Assessment

Vulnerability Type: Use-after-free

Confidence: HIGH

Affected Versions: Pre-7.0-rc6 (before this commit); fixed in v7.0-rc6 and newer

Code Diff

diff --git a/drivers/accel/amdxdna/amdxdna_gem.c b/drivers/accel/amdxdna/amdxdna_gem.c index 238ee244d4a693..6e367ddb9e1bec 100644 --- a/drivers/accel/amdxdna/amdxdna_gem.c +++ b/drivers/accel/amdxdna/amdxdna_gem.c @@ -490,6 +490,9 @@ static struct dma_buf *amdxdna_gem_prime_export(struct drm_gem_object *gobj, int struct amdxdna_gem_obj *abo = to_xdna_obj(gobj); DEFINE_DMA_BUF_EXPORT_INFO(exp_info); + if (abo->private_buffer) + return ERR_PTR(-EOPNOTSUPP); + if (abo->dma_buf) { get_dma_buf(abo->dma_buf); return abo->dma_buf; @@ -685,6 +688,7 @@ amdxdna_gem_create_ubuf_object(struct drm_device *dev, struct amdxdna_drm_create { struct amdxdna_dev *xdna = to_xdna_dev(dev); struct amdxdna_drm_va_tbl va_tbl; + struct amdxdna_gem_obj *abo; struct drm_gem_object *gobj; struct dma_buf *dma_buf; @@ -711,7 +715,10 @@ amdxdna_gem_create_ubuf_object(struct drm_device *dev, struct amdxdna_drm_create dma_buf_put(dma_buf); - return to_xdna_obj(gobj); + abo = to_xdna_obj(gobj); + abo->private_buffer = true; + + return abo; } struct drm_gem_object * diff --git a/drivers/accel/amdxdna/amdxdna_gem.h b/drivers/accel/amdxdna/amdxdna_gem.h index 4fc48a1189d275..957305ccb485af 100644 --- a/drivers/accel/amdxdna/amdxdna_gem.h +++ b/drivers/accel/amdxdna/amdxdna_gem.h @@ -54,6 +54,8 @@ struct amdxdna_gem_obj { /* True, if BO is managed by XRT, not application */ bool internal; + /* True, if BO is not exportable */ + bool private_buffer; }; #define to_gobj(obj) (&(obj)->base.base) diff --git a/drivers/accel/amdxdna/amdxdna_ubuf.c b/drivers/accel/amdxdna/amdxdna_ubuf.c index fb999aa253185e..85390e3cc9f982 100644 --- a/drivers/accel/amdxdna/amdxdna_ubuf.c +++ b/drivers/accel/amdxdna/amdxdna_ubuf.c @@ -69,60 +69,10 @@ static void amdxdna_ubuf_release(struct dma_buf *dbuf) kfree(ubuf); } -static vm_fault_t amdxdna_ubuf_vm_fault(struct vm_fault *vmf) -{ - struct vm_area_struct *vma = vmf->vma; - struct amdxdna_ubuf_priv *ubuf; - unsigned long pfn; - pgoff_t pgoff; - - ubuf = vma->vm_private_data; - pgoff = (vmf->address - vma->vm_start) >> PAGE_SHIFT; - - pfn = page_to_pfn(ubuf->pages[pgoff]); - return vmf_insert_pfn(vma, vmf->address, pfn); -} - -static const struct vm_operations_struct amdxdna_ubuf_vm_ops = { - .fault = amdxdna_ubuf_vm_fault, -}; - -static int amdxdna_ubuf_mmap(struct dma_buf *dbuf, struct vm_area_struct *vma) -{ - struct amdxdna_ubuf_priv *ubuf = dbuf->priv; - - vma->vm_ops = &amdxdna_ubuf_vm_ops; - vma->vm_private_data = ubuf; - vm_flags_set(vma, VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP); - - return 0; -} - -static int amdxdna_ubuf_vmap(struct dma_buf *dbuf, struct iosys_map *map) -{ - struct amdxdna_ubuf_priv *ubuf = dbuf->priv; - void *kva; - - kva = vmap(ubuf->pages, ubuf->nr_pages, VM_MAP, PAGE_KERNEL); - if (!kva) - return -EINVAL; - - iosys_map_set_vaddr(map, kva); - return 0; -} - -static void amdxdna_ubuf_vunmap(struct dma_buf *dbuf, struct iosys_map *map) -{ - vunmap(map->vaddr); -} - static const struct dma_buf_ops amdxdna_ubuf_dmabuf_ops = { .map_dma_buf = amdxdna_ubuf_map, .unmap_dma_buf = amdxdna_ubuf_unmap, .release = amdxdna_ubuf_release, - .mmap = amdxdna_ubuf_mmap, - .vmap = amdxdna_ubuf_vmap, - .vunmap = amdxdna_ubuf_vunmap, }; struct dma_buf *amdxdna_get_ubuf(struct drm_device *dev, diff --git a/drivers/gpu/drm/bridge/chipone-icn6211.c b/drivers/gpu/drm/bridge/chipone-icn6211.c index 814713c5bea97d..553a1df4688d0d 100644 --- a/drivers/gpu/drm/bridge/chipone-icn6211.c +++ b/drivers/gpu/drm/bridge/chipone-icn6211.c @@ -758,7 +758,9 @@ static int chipone_i2c_probe(struct i2c_client *client) dev_set_drvdata(dev, icn); i2c_set_clientdata(client, icn); - drm_bridge_add(&icn->bridge); + ret = devm_drm_bridge_add(dev, &icn->bridge); + if (ret) + return ret; return chipone_dsi_host_attach(icn); } diff --git a/drivers/gpu/drm/bridge/ite-it66121.c b/drivers/gpu/drm/bridge/ite-it66121.c index 9246e9c15a6ef5..ed21f09cd19a33 100644 --- a/drivers/gpu/drm/bridge/ite-it66121.c +++ b/drivers/gpu/drm/bridge/ite-it66121.c @@ -1559,6 +1559,11 @@ static int it66121_probe(struct i2c_client *client) return ret; } + ctx->gpio_reset = devm_gpiod_get(dev, "reset", GPIOD_OUT_LOW); + if (IS_ERR(ctx->gpio_reset)) + return dev_err_probe(dev, PTR_ERR(ctx->gpio_reset), + "Failed to get reset GPIO\n"); + it66121_hw_reset(ctx); ctx->regmap = devm_regmap_init_i2c(client, &it66121_regmap_config); diff --git a/drivers/gpu/drm/bridge/megachips-stdpxxxx-ge-b850v3-fw.c b/drivers/gpu/drm/bridge/megachips-stdpxxxx-ge-b850v3-fw.c index c9e6505cbd8821..2d02cc69f23749 100644 --- a/drivers/gpu/drm/bridge/megachips-stdpxxxx-ge-b850v3-fw.c +++ b/drivers/gpu/drm/bridge/megachips-stdpxxxx-ge-b850v3-fw.c @@ -251,7 +251,6 @@ static void ge_b850v3_lvds_remove(void) goto out; drm_bridge_remove(&ge_b850v3_lvds_ptr->bridge); - ge_b850v3_lvds_ptr = NULL; out: mutex_unlock(&ge_b850v3_lvds_dev_mutex); @@ -261,6 +260,7 @@ static int ge_b850v3_register(void) { struct i2c_client *stdp4028_i2c = ge_b850v3_lvds_ptr->stdp4028_i2c; struct device *dev = &stdp4028_i2c->dev; + int ret; /* drm bridge initialization */ ge_b850v3_lvds_ptr->bridge.ops = DRM_BRIDGE_OP_DETECT | @@ -277,11 +277,15 @@ static int ge_b850v3_register(void) if (!stdp4028_i2c->irq) return 0; - return devm_request_threaded_irq(&stdp4028_i2c->dev, - stdp4028_i2c->irq, NULL, - ge_b850v3_lvds_irq_handler, - IRQF_TRIGGER_HIGH | IRQF_ONESHOT, - "ge-b850v3-lvds-dp", ge_b850v3_lvds_ptr); + ret = devm_request_threaded_irq(&stdp4028_i2c->dev, + stdp4028_i2c->irq, NULL, + ge_b850v3_lvds_irq_handler, + IRQF_TRIGGER_HIGH | IRQF_ONESHOT, + "ge-b850v3-lvds-dp", ge_b850v3_lvds_ptr); + if (ret) + drm_bridge_remove(&ge_b850v3_lvds_ptr->bridge); + + return ret; } static int stdp4028_ge_b850v3_fw_probe(struct i2c_client *stdp4028_i2c) diff --git a/drivers/gpu/drm/drm_drv.c b/drivers/gpu/drm/drm_drv.c index 985c283cf59fa8..675675480da49e 100644 --- a/drivers/gpu/drm/drm_drv.c +++ b/drivers/gpu/drm/drm_drv.c @@ -697,6 +697,7 @@ static void drm_dev_init_release(struct drm_device *dev, void *res) mutex_destroy(&dev->master_mutex); mutex_destroy(&dev->clientlist_mutex); mutex_destroy(&dev->filelist_mutex); + mutex_destroy(&dev->gem_lru_mutex); } static int drm_dev_init(struct drm_device *dev, @@ -738,6 +739,7 @@ static int drm_dev_init(struct drm_device *dev, INIT_LIST_HEAD(&dev->vblank_event_list); spin_lock_init(&dev->event_lock); + mutex_init(&dev->gem_lru_mutex); mutex_init(&dev->filelist_mutex); mutex_init(&dev->clientlist_mutex); mutex_init(&dev->master_mutex); diff --git a/drivers/gpu/drm/drm_gem.c b/drivers/gpu/drm/drm_gem.c index 8afab57fc0554e..e3b8a1f353cb92 100644 --- a/drivers/gpu/drm/drm_gem.c +++ b/drivers/gpu/drm/drm_gem.c @@ -1561,12 +1561,10 @@ EXPORT_SYMBOL(drm_gem_unlock_reservations); * drm_gem_lru_init - initialize a LRU * * @lru: The LRU to initialize - * @lock: The lock protecting the LRU */ void -drm_gem_lru_init(struct drm_gem_lru *lru, struct mutex *lock) +drm_gem_lru_init(struct drm_gem_lru *lru) { - lru->lock = lock; lru->count = 0; INIT_LIST_HEAD(&lru->list); } @@ -1591,14 +1589,10 @@ drm_gem_lru_remove_locked(struct drm_gem_object *obj) void drm_gem_lru_remove(struct drm_gem_object *obj) { - struct drm_gem_lru *lru = obj->lru; - - if (!lru) - return; - - mutex_lock(lru->lock); - drm_gem_lru_remove_locked(obj); - mutex_unlock(lru->lock); + mutex_lock(&obj->dev->gem_lru_mutex); + if (obj->lru) + drm_gem_lru_remove_locked(obj); + mutex_unlock(&obj->dev->gem_lru_mutex); } EXPORT_SYMBOL(drm_gem_lru_remove); @@ -1613,7 +1607,7 @@ EXPORT_SYMBOL(drm_gem_lru_remove); void drm_gem_lru_move_tail_locked(struct drm_gem_lru *lru, struct drm_gem_object *obj) { - lockdep_assert_held_once(lru->lock); + lockdep_assert_held_once(&obj->dev->gem_lru_mutex); if (obj->lru) drm_gem_lru_remove_locked(obj); @@ -1637,9 +1631,9 @@ EXPORT_SYMBOL(drm_gem_lru_move_tail_locked); void drm_gem_lru_move_tail(struct drm_gem_lru *lru, struct drm_gem_object *obj) { - mutex_lock(lru->lock); + mutex_lock(&obj->dev->gem_lru_mutex); drm_gem_lru_move_tail_locked(lru, obj); - mutex_unlock(lru->lock); + mutex_unlock(&obj->dev->gem_lru_mutex); } EXPORT_SYMBOL(drm_gem_lru_move_tail); @@ -1653,6 +1647,7 @@ EXPORT_SYMBOL(drm_gem_lru_move_tail); * of the shrink callback to check for this (ie. dma_resv_test_signaled()) * or if necessary block until the buffer becomes idle. * + * @dev: DRM device the LRU belongs to * @lru: The LRU to scan * @nr_to_scan: The number of pages to try to reclaim * @remaining: The number of pages left to reclaim, should be initialized by caller @@ -1660,7 +1655,8 @@ EXPORT_SYMBOL(drm_gem_lru_move_tail); * @ticket: Optional ww_acquire_ctx context to use for locking */ unsigned long -drm_gem_lru_scan(struct drm_gem_lru *lru, +drm_gem_lru_scan(struct drm_device *dev, + struct drm_gem_lru *lru, unsigned int nr_to_scan, unsigned long *remaining, bool (*shrink)(struct drm_gem_object *obj, struct ww_acquire_ctx *ticket), @@ -1670,9 +1666,9 @@ drm_gem_lru_scan(struct drm_gem_lru *lru, struct drm_gem_object *obj; unsigned freed = 0; - drm_gem_lru_init(&still_in_lru, lru->lock); + drm_gem_lru_init(&still_in_lru); - mutex_lock(lru->lock); + mutex_lock(&dev->gem_lru_mutex); while (freed < nr_to_scan) { obj = list_first_entry_or_null(&lru->list, typeof(*obj), lru_node); @@ -1695,7 +1691,7 @@ drm_gem_lru_scan(struct drm_gem_lru *lru, * rest of the loop body, to reduce contention with other * code paths that need the LRU lock */ - mutex_unlock(lru->lock); + mutex_unlock(&dev->gem_lru_mutex); if (ticket) ww_acquire_init(ticket, &reservation_ww_class); @@ -1729,7 +1725,7 @@ drm_gem_lru_scan(struct drm_gem_lru *lru, tail: drm_gem_object_put(obj); - mutex_lock(lru->lock); + mutex_lock(&dev->gem_lru_mutex); } /* @@ -1741,7 +1737,7 @@ drm_gem_lru_scan(struct drm_gem_lru *lru, list_splice_tail(&still_in_lru.list, &lru->list); lru->count += still_in_lru.count; - mutex_unlock(lru->lock); + mutex_unlock(&dev->gem_lru_mutex); return freed; } diff --git a/drivers/gpu/drm/msm/msm_drv.c b/drivers/gpu/drm/msm/msm_drv.c index 195f40e331e5a8..cc2bcd14b1c26b 100644 --- a/drivers/gpu/drm/msm/msm_drv.c +++ b/drivers/gpu/drm/msm/msm_drv.c @@ -128,11 +128,10 @@ static int msm_drm_init(struct device *dev, const struct drm_driver *drv, /* * Initialize the LRUs: */ - mutex_init(&priv->lru.lock); - drm_gem_lru_init(&priv->lru.unbacked, &priv->lru.lock); - drm_gem_lru_init(&priv->lru.pinned, &priv->lru.lock); - drm_gem_lru_init(&priv->lru.willneed, &priv->lru.lock); - drm_gem_lru_init(&priv->lru.dontneed, &priv->lru.lock); + drm_gem_lru_init(&priv->lru.unbacked); + drm_gem_lru_init(&priv->lru.pinned); + drm_gem_lru_init(&priv->lru.willneed); + drm_gem_lru_init(&priv->lru.dontneed); /* Initialize stall-on-fault */ spin_lock_init(&priv->fault_stall_lock); @@ -140,7 +139,7 @@ static int msm_drm_init(struct device *dev, const struct drm_driver *drv, /* Teach lockdep about lock ordering wrt. shrinker: */ fs_reclaim_acquire(GFP_KERNEL); - might_lock(&priv->lru.lock); + might_lock(&ddev->gem_lru_mutex); fs_reclaim_release(GFP_KERNEL); if (priv->kms_init) { diff --git a/drivers/gpu/drm/msm/msm_drv.h b/drivers/gpu/drm/msm/msm_drv.h index 6d847d593f1aeb..617b3c4b42c0cf 100644 --- a/drivers/gpu/drm/msm/msm_drv.h +++ b/drivers/gpu/drm/msm/msm_drv.h @@ -150,13 +150,6 @@ struct msm_drm_private { * DONTNEED state (ie. can be purged) */ struct drm_gem_lru dontneed; - - /** - * lock: - * - * Protects manipulation of all of the LRUs. - */ - struct mutex lock; } lru; struct notifier_block vmap_notifier; diff --git a/drivers/gpu/drm/msm/msm_gem.c b/drivers/gpu/drm/msm/msm_gem.c index 2cb3ab04f12502..efd3d3c9a4490c 100644 --- a/drivers/gpu/drm/msm/msm_gem.c +++ b/drivers/gpu/drm/msm/msm_gem.c @@ -177,11 +177,11 @@ static void update_lru_locked(struct drm_gem_object *obj) static void update_lru(struct drm_gem_object *obj) { - struct msm_drm_private *priv = obj->dev->dev_private; + struct drm_device *dev = obj->dev; - mutex_lock(&priv->lru.lock); + mutex_lock(&dev->gem_lru_mutex); update_lru_locked(obj); - mutex_unlock(&priv->lru.lock); + mutex_unlock(&dev->gem_lru_mutex); } static struct page **get_pages(struct drm_gem_object *obj) @@ -292,11 +292,11 @@ void msm_gem_pin_obj_locked(struct drm_gem_object *obj) static void pin_obj_locked(struct drm_gem_object *obj) { - struct msm_drm_private *priv = obj->dev->dev_private; + struct drm_device *dev = obj->dev; - mutex_lock(&priv->lru.lock); + mutex_lock(&dev->gem_lru_mutex); msm_gem_pin_obj_locked(obj); - mutex_unlock(&priv->lru.lock); + mutex_unlock(&dev->gem_lru_mutex); } struct page **msm_gem_pin_pages_locked(struct drm_gem_object *obj) @@ -487,16 +487,16 @@ int msm_gem_pin_vma_locked(struct drm_gem_object *obj, struct drm_gpuva *vma) void msm_gem_unpin_locked(struct drm_gem_object *obj) { - struct msm_drm_private *priv = obj->dev->dev_private; + struct drm_device *dev = obj->dev; struct msm_gem_object *msm_obj = to_msm_bo(obj); msm_gem_assert_locked(obj); - mutex_lock(&priv->lru.lock); + mutex_lock(&dev->gem_lru_mutex); msm_obj->pin_count--; GEM_WARN_ON(msm_obj->pin_count < 0); update_lru_locked(obj); - mutex_unlock(&priv->lru.lock); + mutex_unlock(&dev->gem_lru_mutex); } /* Special unpin path for use in fence-signaling path, avoiding the need @@ -507,10 +507,10 @@ void msm_gem_unpin_locked(struct drm_gem_object *obj) */ void msm_gem_unpin_active(struct drm_gem_object *obj) { - struct msm_drm_private *priv = obj->dev->dev_private; + struct drm_device *dev = obj->dev; struct msm_gem_object *msm_obj = to_msm_bo(obj); - GEM_WARN_ON(!mutex_is_locked(&priv->lru.lock)); + GEM_WARN_ON(!mutex_is_locked(&dev->gem_lru_mutex)); msm_obj->pin_count--; GEM_WARN_ON(msm_obj->pin_count < 0); @@ -797,12 +797,12 @@ void msm_gem_put_vaddr(struct drm_gem_object *obj) */ int msm_gem_madvise(struct drm_gem_object *obj, unsigned madv) { - struct msm_drm_private *priv = obj->dev->dev_private; + struct drm_device *dev = obj->dev; struct msm_gem_object *msm_obj = to_msm_bo(obj); msm_gem_lock(obj); - mutex_lock(&priv->lru.lock); + mutex_lock(&dev->gem_lru_mutex); if (msm_obj->madv != __MSM_MADV_PURGED) msm_obj->madv = madv; @@ -814,7 +814,7 @@ int msm_gem_madvise(struct drm_gem_object *obj, unsigned madv) */ update_lru_locked(obj); - mutex_unlock(&priv->lru.lock); + mutex_unlock(&dev->gem_lru_mutex); msm_gem_unlock(obj); @@ -824,7 +824,6 @@ int msm_gem_madvise(struct drm_gem_object *obj, unsigned madv) void msm_gem_purge(struct drm_gem_object *obj) { struct drm_device *dev = obj->dev; - struct msm_drm_private *priv = obj->dev->dev_private; struct msm_gem_object *msm_obj = to_msm_bo( ... [truncated]
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