Use-after-free
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]