From 491adc6a0f9903c32b05f284df1148de39e8e644 Mon Sep 17 00:00:00 2001 From: Simon Richter Date: Tue, 14 Oct 2025 01:11:33 +0900 Subject: [PATCH] drm/ttm: Avoid NULL pointer deref for evicted BOs MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit It is possible for a BO to exist that is not currently associated with a resource, e.g. because it has been evicted. When devcoredump tries to read the contents of all BOs for dumping, we need to expect this as well -- in this case, ENODATA is recorded instead of the buffer contents. Fixes: 7d08df5d0bd3 ("drm/ttm: Add ttm_bo_access") Fixes: 09ac4fcb3f25 ("drm/ttm: Implement vm_operations_struct.access v2") Cc: stable Closes: https://gitlab.freedesktop.org/drm/xe/kernel/-/issues/6271 Signed-off-by: Simon Richter Reviewed-by: Matthew Brost Reviewed-by: Shuicheng Lin Reviewed-by: Christian König Signed-off-by: Matthew Brost Link: https://patch.msgid.link/20251013161241.709916-1-Simon.Richter@hogyros.de --- drivers/gpu/drm/ttm/ttm_bo_vm.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/drivers/gpu/drm/ttm/ttm_bo_vm.c b/drivers/gpu/drm/ttm/ttm_bo_vm.c index b47020fca1992..e6abc7b40b189 100644 --- a/drivers/gpu/drm/ttm/ttm_bo_vm.c +++ b/drivers/gpu/drm/ttm/ttm_bo_vm.c @@ -434,6 +434,11 @@ int ttm_bo_access(struct ttm_buffer_object *bo, unsigned long offset, if (ret) return ret; + if (!bo->resource) { + ret = -ENODATA; + goto unlock; + } + switch (bo->resource->mem_type) { case TTM_PL_SYSTEM: fallthrough; @@ -448,6 +453,7 @@ int ttm_bo_access(struct ttm_buffer_object *bo, unsigned long offset, ret = -EIO; } +unlock: ttm_bo_unreserve(bo); return ret; -- 2.47.3