| Message ID | 20180901122041.2357-1-baijiaju1990@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | gpu: drm: drm_mm: Fix a sleep-in-atomic-context bug in show_leaks() | expand |
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
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;
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(-)