linux-kernel - [PATCH -next] drm/amdkfd: Fix NULL pointer dereference in svm_migrate_to

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Message-Id: <20221026020054.57114-1-yang.lee@linux.alibaba.com>
Date:   Wed, 26 Oct 2022 10:00:54 +0800
From:   Yang Li <yang.lee@...ux.alibaba.com>
To:     Felix.Kuehling@....com, alexander.deucher@....com
Cc:     christian.koenig@....com, Xinhui.Pan@....com, airlied@...il.com,
        daniel@...ll.ch, amd-gfx@...ts.freedesktop.org,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        Yang Li <yang.lee@...ux.alibaba.com>,
        Abaci Robot <abaci@...ux.alibaba.com>
Subject: [PATCH -next] drm/amdkfd: Fix NULL pointer dereference in svm_migrate_to_ram()

./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@...ux.alibaba.com>
Signed-off-by: Yang Li <yang.lee@...ux.alibaba.com>
---

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;
 }
 
-- 
2.20.1.7.g153144c