The driver may sleep with holding a spinlock.
The function call paths (from bottom to top) in Linux-4.16 are:
[FUNC] kmalloc(GFP_KERNEL) drivers/gpu/drm/drm_mm.c, 130: kmalloc in show_leaks drivers/gpu/drm/drm_mm.c, 913: show_leaks in drm_mm_takedown drivers/gpu/drm/drm_vma_manager.c, 107: drm_mm_takedown in drm_vma_offset_manager_destroy drivers/gpu/drm/drm_vma_manager.c, 106: _raw_write_lock in drm_vma_offset_manager_destroy
[FUNC] kmalloc(GFP_KERNEL) drivers/gpu/drm/drm_mm.c, 130: kmalloc in show_leaks drivers/gpu/drm/drm_mm.c, 913: show_leaks in drm_mm_takedown drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c, 71: drm_mm_takedown in amdgpu_vram_mgr_fini drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c, 70: spin_lock in amdgpu_vram_mgr_fini
[FUNC] kmalloc(GFP_KERNEL) drivers/gpu/drm/drm_mm.c, 130: kmalloc in show_leaks drivers/gpu/drm/drm_mm.c, 913: show_leaks in drm_mm_takedown drivers/gpu/drm/ttm/ttm_bo_manager.c, 128: drm_mm_takedown in ttm_bo_man_takedown drivers/gpu/drm/ttm/ttm_bo_manager.c, 126: spin_lock in ttm_bo_man_takedown
To fix this bug, GFP_KERNEL is replaced with GFP_ATOMIC.
This bug is found by my static analysis tool DSAC.
Signed-off-by: Jia-Ju Bai baijiaju1990@gmail.com --- drivers/gpu/drm/drm_mm.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/drm_mm.c b/drivers/gpu/drm/drm_mm.c index 3166026a1874..2486121a78d4 100644 --- a/drivers/gpu/drm/drm_mm.c +++ b/drivers/gpu/drm/drm_mm.c @@ -127,7 +127,7 @@ static void show_leaks(struct drm_mm *mm) unsigned long entries[STACKDEPTH]; char *buf;
- buf = kmalloc(BUFSZ, GFP_KERNEL); + buf = kmalloc(BUFSZ, GFP_ATOMIC); if (!buf) return;
Quoting Jia-Ju Bai (2018-09-01 13:20:41)
The driver may sleep with holding a spinlock.
The function call paths (from bottom to top) in Linux-4.16 are:
[FUNC] kmalloc(GFP_KERNEL) drivers/gpu/drm/drm_mm.c, 130: kmalloc in show_leaks drivers/gpu/drm/drm_mm.c, 913: show_leaks in drm_mm_takedown drivers/gpu/drm/drm_vma_manager.c, 107: drm_mm_takedown in drm_vma_offset_manager_destroy drivers/gpu/drm/drm_vma_manager.c, 106: _raw_write_lock in drm_vma_offset_manager_destroy
[FUNC] kmalloc(GFP_KERNEL) drivers/gpu/drm/drm_mm.c, 130: kmalloc in show_leaks drivers/gpu/drm/drm_mm.c, 913: show_leaks in drm_mm_takedown drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c, 71: drm_mm_takedown in amdgpu_vram_mgr_fini drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c, 70: spin_lock in amdgpu_vram_mgr_fini
[FUNC] kmalloc(GFP_KERNEL) drivers/gpu/drm/drm_mm.c, 130: kmalloc in show_leaks drivers/gpu/drm/drm_mm.c, 913: show_leaks in drm_mm_takedown drivers/gpu/drm/ttm/ttm_bo_manager.c, 128: drm_mm_takedown in ttm_bo_man_takedown drivers/gpu/drm/ttm/ttm_bo_manager.c, 126: spin_lock in ttm_bo_man_takedown
To fix this bug, GFP_KERNEL is replaced with GFP_ATOMIC.
The bug are above, since those spinlocks do not protect the data and imply use-after-free. -Chris
On Sat, Sep 01, 2018 at 01:32:54PM +0100, Chris Wilson wrote:
Quoting Jia-Ju Bai (2018-09-01 13:20:41)
The driver may sleep with holding a spinlock.
The function call paths (from bottom to top) in Linux-4.16 are:
[FUNC] kmalloc(GFP_KERNEL) drivers/gpu/drm/drm_mm.c, 130: kmalloc in show_leaks drivers/gpu/drm/drm_mm.c, 913: show_leaks in drm_mm_takedown drivers/gpu/drm/drm_vma_manager.c, 107: drm_mm_takedown in drm_vma_offset_manager_destroy drivers/gpu/drm/drm_vma_manager.c, 106: _raw_write_lock in drm_vma_offset_manager_destroy
[FUNC] kmalloc(GFP_KERNEL) drivers/gpu/drm/drm_mm.c, 130: kmalloc in show_leaks drivers/gpu/drm/drm_mm.c, 913: show_leaks in drm_mm_takedown drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c, 71: drm_mm_takedown in amdgpu_vram_mgr_fini drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c, 70: spin_lock in amdgpu_vram_mgr_fini
[FUNC] kmalloc(GFP_KERNEL) drivers/gpu/drm/drm_mm.c, 130: kmalloc in show_leaks drivers/gpu/drm/drm_mm.c, 913: show_leaks in drm_mm_takedown drivers/gpu/drm/ttm/ttm_bo_manager.c, 128: drm_mm_takedown in ttm_bo_man_takedown drivers/gpu/drm/ttm/ttm_bo_manager.c, 126: spin_lock in ttm_bo_man_takedown
To fix this bug, GFP_KERNEL is replaced with GFP_ATOMIC.
The bug are above, since those spinlocks do not protect the data and imply use-after-free.
Adding amdgpu, since that's where the bug seems to be. -Daniel
Am 03.09.2018 um 09:52 schrieb Daniel Vetter:
On Sat, Sep 01, 2018 at 01:32:54PM +0100, Chris Wilson wrote:
Quoting Jia-Ju Bai (2018-09-01 13:20:41)
The driver may sleep with holding a spinlock.
The function call paths (from bottom to top) in Linux-4.16 are:
[FUNC] kmalloc(GFP_KERNEL) drivers/gpu/drm/drm_mm.c, 130: kmalloc in show_leaks drivers/gpu/drm/drm_mm.c, 913: show_leaks in drm_mm_takedown drivers/gpu/drm/drm_vma_manager.c, 107: drm_mm_takedown in drm_vma_offset_manager_destroy drivers/gpu/drm/drm_vma_manager.c, 106: _raw_write_lock in drm_vma_offset_manager_destroy
[FUNC] kmalloc(GFP_KERNEL) drivers/gpu/drm/drm_mm.c, 130: kmalloc in show_leaks drivers/gpu/drm/drm_mm.c, 913: show_leaks in drm_mm_takedown drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c, 71: drm_mm_takedown in amdgpu_vram_mgr_fini drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c, 70: spin_lock in amdgpu_vram_mgr_fini
[FUNC] kmalloc(GFP_KERNEL) drivers/gpu/drm/drm_mm.c, 130: kmalloc in show_leaks drivers/gpu/drm/drm_mm.c, 913: show_leaks in drm_mm_takedown drivers/gpu/drm/ttm/ttm_bo_manager.c, 128: drm_mm_takedown in ttm_bo_man_takedown drivers/gpu/drm/ttm/ttm_bo_manager.c, 126: spin_lock in ttm_bo_man_takedown
To fix this bug, GFP_KERNEL is replaced with GFP_ATOMIC.
The bug are above, since those spinlocks do not protect the data and imply use-after-free.
Adding amdgpu, since that's where the bug seems to be.
When we have use after free we might have concurrent uses as well.
I think taking the lock here is probably a good idea if you don't want to accidentally access freed memory in show_leaks.
So Chris change sounds valid to me.
Christian.
-Daniel
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