Re: [PATCH -next] drm/amdkfd: Fix NULL pointer dereference in svm_migrate_to_ram()

From: Felix Kuehling
Date: Wed Oct 26 2022 - 16:37:58 EST


On 2022-10-25 22:00, Yang Li wrote:
./drivers/gpu/drm/amd/amdkfd/kfd_migrate.c:985:58-62: ERROR: p is NULL but dereferenced.

Link: https://bugzilla.openanolis.cn/show_bug.cgi?id=2549
Reported-by: Abaci Robot <abaci@xxxxxxxxxxxxxxxxx>
Signed-off-by: Yang Li <yang.lee@xxxxxxxxxxxxxxxxx>

The patch is

Reviewed-by: Felix Kuehling <Felix.Kuehling@xxxxxxx>

I applied to our amd-staging-drm-next branch.

Thanks,
  Felix


---

change in v2:
According to Felix's suggestion, move the pr_debug up before the kfd_unref_process
call.

drivers/gpu/drm/amd/amdkfd/kfd_migrate.c | 4 +---
1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_migrate.c b/drivers/gpu/drm/amd/amdkfd/kfd_migrate.c
index 20d6b2578927..b9c8d29d95aa 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_migrate.c
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_migrate.c
@@ -978,12 +978,10 @@ static vm_fault_t svm_migrate_to_ram(struct vm_fault *vmf)
out_unlock_svms:
mutex_unlock(&p->svms.lock);
out_unref_process:
+ pr_debug("CPU fault svms 0x%p address 0x%lx done\n", &p->svms, addr);
kfd_unref_process(p);
out_mmput:
mmput(mm);
-
- pr_debug("CPU fault svms 0x%p address 0x%lx done\n", &p->svms, addr);
-
return r ? VM_FAULT_SIGBUS : 0;
}