[PATCH 5.18 0330/1095] virtio-gpu: fix a missing check to avoid NULL dereference

Greg Kroah-Hartman
2022-08-15T20:58:24Z

From: Xiaomeng Tong <xiam0nd.tong@gmail.com>

[ Upstream commit bd63f11f4c3c46afec07d821f74736161ff6e526 ]

'cache_ent' could be set NULL inside virtio_gpu_cmd_get_capset()
and it will lead to a NULL dereference by a lately use of it
(i.e., ptr = cache_ent->caps_cache). Fix it with a NULL check.

Fixes: 62fb7a5e10962 ("virtio-gpu: add 3d/virgl support")
Signed-off-by: Xiaomeng Tong <xiam0nd.tong@gmail.com>
Reviewed-by: Chia-I Wu <olvaffe@gmail.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20220327050945.1614-1-xiam0nd.tong@gmail.com

[ kraxel: minor codestyle fixup ]

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/gpu/drm/virtio/virtgpu_ioctl.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/virtio/virtgpu_ioctl.c b/drivers/gpu/drm/virtio/virtgpu_ioctl.c
index c708bab555c6..10f080060923 100644
--- a/drivers/gpu/drm/virtio/virtgpu_ioctl.c
+++ b/drivers/gpu/drm/virtio/virtgpu_ioctl.c
@@ -579,8 +579,10 @@ static int virtio_gpu_get_caps_ioctl(struct drm_device *dev,
spin_unlock(&vgdev->display_info_lock);

/* not in cache - need to talk to hw */
- virtio_gpu_cmd_get_capset(vgdev, found_valid, args->cap_set_ver,
- &cache_ent);
+ ret = virtio_gpu_cmd_get_capset(vgdev, found_valid, args->cap_set_ver,
+ &cache_ent);
+ if (ret)
+ return ret;
virtio_gpu_notify(vgdev);

copy_exit:
--
2.35.1