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| author | Sebastian Brzezinka <sebastian.brzezinka@intel.com> | 2026-03-03 13:26:42 +0100 |
|---|---|---|
| committer | Christian König <christian.koenig@amd.com> | 2026-03-05 08:51:35 +0100 |
| commit | 21613f67ede11e495281b4a6dde72cd7db3ada4e (patch) | |
| tree | 99ecfdfeee1a6c9808bce6752d59dd75946edcd3 | |
| parent | d2e20c8951e4bb5f4a828aed39813599980353b6 (diff) | |
| download | linux-21613f67ede11e495281b4a6dde72cd7db3ada4e.tar.gz linux-21613f67ede11e495281b4a6dde72cd7db3ada4e.zip | |
drm/ttm: fix NULL deref in ttm_bo_flush_all_fences() after fence ops detach
Since commit 541c8f2468b9 ("dma-buf: detach fence ops on signal v3"),
fence->ops may be set to NULL via RCU when a fence signals and has no
release/wait ops. ttm_bo_flush_all_fences() was not updated to handle
this and directly dereferences fence->ops->signaled, leading to a NULL
pointer dereference crash:
```
BUG: kernel NULL pointer dereference, address: 0000000000000018
RIP: 0010:ttm_bo_release+0x1bc/0x330 [ttm]
```
Since dma_fence_enable_sw_signaling() already handles the signaled case
internally (it checks DMA_FENCE_FLAG_SIGNALED_BIT before doing anything),
the ops->signaled pre-check is redundant. Simply remove it and call
dma_fence_enable_sw_signaling() unconditionally for each fence.
Closes: https://gitlab.freedesktop.org/drm/i915/kernel/-/issues/15759
Fixes: 541c8f2468b9 ("dma-buf: detach fence ops on signal v3")
Cc: Christian König <christian.koenig@amd.com>
Signed-off-by: Sebastian Brzezinka <sebastian.brzezinka@intel.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Andi Shyti <andi.shyti@linux.intel.com>
Signed-off-by: Christian König <christian.koenig@amd.com>
Link: https://lore.kernel.org/r/1c2f34351b6fb70ab576aeac07987542a4d480b2.1772540459.git.sebastian.brzezinka@intel.com
| -rw-r--r-- | drivers/gpu/drm/ttm/ttm_bo.c | 6 |
1 files changed, 2 insertions, 4 deletions
diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c index acb9197db879..0485ad00a3df 100644 --- a/drivers/gpu/drm/ttm/ttm_bo.c +++ b/drivers/gpu/drm/ttm/ttm_bo.c @@ -222,10 +222,8 @@ static void ttm_bo_flush_all_fences(struct ttm_buffer_object *bo) struct dma_fence *fence; dma_resv_iter_begin(&cursor, resv, DMA_RESV_USAGE_BOOKKEEP); - dma_resv_for_each_fence_unlocked(&cursor, fence) { - if (!fence->ops->signaled) - dma_fence_enable_sw_signaling(fence); - } + dma_resv_for_each_fence_unlocked(&cursor, fence) + dma_fence_enable_sw_signaling(fence); dma_resv_iter_end(&cursor); } |