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From:   Zheng Wang <zyytlz.wz@163.com>
To:     nouveau@lists.freedesktop.org
Cc:     bskeggs@redhat.com, kherbst@redhat.com, lyude@redhat.com,
        airlied@gmail.com, hackerzheng666@gmail.com,
        alex000young@gmail.com, security@kernel.org, daniel@ffwll.ch,
        Julia.Lawall@inria.fr, linux-kernel@vger.kernel.org,
        Zheng Wang <zyytlz.wz@163.com>
Subject: [PATCH] drm/nouveau/mmu: fix use-after-free bug in nvkm_vmm_pfn_map
Date:   Sat, 29 Oct 2022 15:46:54 +0800
Message-Id: <20221029074654.203153-1-zyytlz.wz@163.com>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

If it failed in kzalloc, vma will be freed in nvkm_vmm_node_merge.
The later use of vma will casue use after free.

Reported-by: Zheng Wang <hackerzheng666@gmail.com>
Reported-by: Zhuorao Yang <alex000young@gmail.com>

Fix it by returning to upper caller as soon as error occurs.

Signed-off-by: Zheng Wang <zyytlz.wz@163.com>
---
 drivers/gpu/drm/nouveau/nvkm/subdev/mmu/vmm.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/nouveau/nvkm/subdev/mmu/vmm.c b/drivers/gpu/drm/nouveau/nvkm/subdev/mmu/vmm.c
index ae793f400ba1..04befd28f80b 100644
--- a/drivers/gpu/drm/nouveau/nvkm/subdev/mmu/vmm.c
+++ b/drivers/gpu/drm/nouveau/nvkm/subdev/mmu/vmm.c
@@ -1272,8 +1272,7 @@ nvkm_vmm_pfn_map(struct nvkm_vmm *vmm, u8 shift, u64 addr, u64 size, u64 *pfn)
 						       page -
 						       vmm->func->page, map);
 			if (WARN_ON(!tmp)) {
-				ret = -ENOMEM;
-				goto next;
+				return -ENOMEM;
 			}
 
 			if ((tmp->mapped = map))
-- 
2.25.1