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authorPavel Skripkin <paskripkin@gmail.com>2021-07-08 14:25:18 +0300
committerChristian König <christian.koenig@amd.com>2021-07-21 13:00:40 +0200
commit2dbd9c27eda5cf83aa990266a3355960d860da71 (patch)
treec41f9628bb77151a28a1447716a39aed1048e9ae
parent235c3610d5f02ee91244239b43cd9ae8b4859dff (diff)
drm/ttm: add missing NULL checks
My local syzbot instance hit GPF in ttm_bo_release(). Unfortunately, syzbot didn't produce a reproducer for this, but I found out possible scenario: drm_gem_vram_create() <-- drm_gem_vram_object kzalloced (bo embedded in this object) ttm_bo_init() ttm_bo_init_reserved() ttm_resource_alloc() man->func->alloc() <-- allocation failure ttm_bo_put() ttm_bo_release() ttm_mem_io_free() <-- bo->resource == NULL passed as second argument *GPF* Added NULL check inside ttm_mem_io_free() to prevent reported GPF and make this function NULL save in future. Same problem was in ttm_bo_move_to_lru_tail() as Christian reported. ttm_bo_move_to_lru_tail() is called in ttm_bo_release() and mem pointer can be NULL as well as in ttm_mem_io_free(). Fail log: KASAN: null-ptr-deref in range [0x0000000000000020-0x0000000000000027] ... RIP: 0010:ttm_mem_io_free+0x28/0x170 drivers/gpu/drm/ttm/ttm_bo_util.c:66 .. Call Trace: ttm_bo_release+0xd94/0x10a0 drivers/gpu/drm/ttm/ttm_bo.c:422 kref_put include/linux/kref.h:65 [inline] ttm_bo_put drivers/gpu/drm/ttm/ttm_bo.c:470 [inline] ttm_bo_init_reserved+0x7cb/0x960 drivers/gpu/drm/ttm/ttm_bo.c:1050 ttm_bo_init+0x105/0x270 drivers/gpu/drm/ttm/ttm_bo.c:1074 drm_gem_vram_create+0x332/0x4c0 drivers/gpu/drm/drm_gem_vram_helper.c:228 Fixes: d3116756a710 ("drm/ttm: rename bo->mem and make it a pointer") Signed-off-by: Pavel Skripkin <paskripkin@gmail.com> Reviewed-by: Christian König <christian.koenig@amd.com> Signed-off-by: Christian König <christian.koenig@amd.com> Link: https://patchwork.freedesktop.org/patch/msgid/20210708112518.17271-1-paskripkin@gmail.com
-rw-r--r--drivers/gpu/drm/ttm/ttm_bo.c3
-rw-r--r--drivers/gpu/drm/ttm/ttm_bo_util.c3
2 files changed, 6 insertions, 0 deletions
diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c
index 1b950b45cf4b..8d7fd65ccced 100644
--- a/drivers/gpu/drm/ttm/ttm_bo.c
+++ b/drivers/gpu/drm/ttm/ttm_bo.c
@@ -102,6 +102,9 @@ void ttm_bo_move_to_lru_tail(struct ttm_buffer_object *bo,
return;
}
+ if (!mem)
+ return;
+
man = ttm_manager_type(bdev, mem->mem_type);
list_move_tail(&bo->lru, &man->lru[bo->priority]);
diff --git a/drivers/gpu/drm/ttm/ttm_bo_util.c b/drivers/gpu/drm/ttm/ttm_bo_util.c
index 2f57f824e6db..763fa6f4e07d 100644
--- a/drivers/gpu/drm/ttm/ttm_bo_util.c
+++ b/drivers/gpu/drm/ttm/ttm_bo_util.c
@@ -63,6 +63,9 @@ int ttm_mem_io_reserve(struct ttm_device *bdev,
void ttm_mem_io_free(struct ttm_device *bdev,
struct ttm_resource *mem)
{
+ if (!mem)
+ return;
+
if (!mem->bus.offset && !mem->bus.addr)
return;