[PATCH 4.9 045/240] drm/amdgpu: fix NULL pointer dereference

Greg Kroah-Hartman
2021-05-20T11:05:09Z

From: Guchun Chen <guchun.chen@amd.com>

[ Upstream commit 3c3dc654333f6389803cdcaf03912e94173ae510 ]

ttm->sg needs to be checked before accessing its child member.

Call Trace:
amdgpu_ttm_backend_destroy+0x12/0x70 [amdgpu]
ttm_bo_cleanup_memtype_use+0x3a/0x60 [ttm]
ttm_bo_release+0x17d/0x300 [ttm]
amdgpu_bo_unref+0x1a/0x30 [amdgpu]
amdgpu_amdkfd_gpuvm_alloc_memory_of_gpu+0x78b/0x8b0 [amdgpu]
kfd_ioctl_alloc_memory_of_gpu+0x118/0x220 [amdgpu]
kfd_ioctl+0x222/0x400 [amdgpu]
? kfd_dev_is_large_bar+0x90/0x90 [amdgpu]
__x64_sys_ioctl+0x8e/0xd0
? __context_tracking_exit+0x52/0x90
do_syscall_64+0x33/0x80
entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x7f97f264d317
Code: b3 66 90 48 8b 05 71 4b 2d 00 64 c7 00 26 00 00 00 48 c7 c0 ff ff ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 b8 10 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 41 4b 2d 00 f7 d8 64 89 01 48
RSP: 002b:00007ffdb402c338 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f97f3cc63a0 RCX: 00007f97f264d317
RDX: 00007ffdb402c380 RSI: 00000000c0284b16 RDI: 0000000000000003
RBP: 00007ffdb402c380 R08: 00007ffdb402c428 R09: 00000000c4000004
R10: 00000000c4000004 R11: 0000000000000246 R12: 00000000c0284b16
R13: 0000000000000003 R14: 00007f97f3cc63a0 R15: 00007f8836200000

Signed-off-by: Guchun Chen <guchun.chen@amd.com>
Acked-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
index 80c60a62d39e..7271e3f32d82 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
@@ -652,7 +652,7 @@ static void amdgpu_ttm_tt_unpin_userptr(struct ttm_tt *ttm)
DMA_BIDIRECTIONAL : DMA_TO_DEVICE;

/* double check that we don't free the table twice */
- if (!ttm->sg->sgl)
+ if (!ttm->sg || !ttm->sg->sgl)
return;

/* free the sg table and pages again */
--
2.30.2