linux-kernel - [PATCH] drm/virtio: Ensure that objs is not NULL in virtio_gpu_array_put

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Date:   Mon, 13 Dec 2021 19:31:22 +0100
From:   Roberto Sassu <roberto.sassu@...wei.com>
To:     <airlied@...ux.ie>, <kraxel@...hat.com>, <daniel@...ll.ch>
CC:     <dri-devel@...ts.freedesktop.org>,
        <virtualization@...ts.linux-foundation.org>,
        <linux-kernel@...r.kernel.org>,
        Roberto Sassu <roberto.sassu@...wei.com>,
        <stable@...r.kernel.org>,
        <syzbot+e9072e90624a31dfa85f@...kaller.appspotmail.com>
Subject: [PATCH] drm/virtio: Ensure that objs is not NULL in virtio_gpu_array_put_free()

If virtio_gpu_object_shmem_init() fails (e.g. due to fault injection, as it
happened in the bug report by syzbot), virtio_gpu_array_put_free() could be
called with objs equal to NULL.

Ensure that objs is not NULL in virtio_gpu_array_put_free(), or otherwise
return from the function.

Cc: stable@...r.kernel.org # 5.13.x
Signed-off-by: Roberto Sassu <roberto.sassu@...wei.com>
Reported-by: syzbot+e9072e90624a31dfa85f@...kaller.appspotmail.com
Fixes: 377f8331d0565 ("drm/virtio: fix possible leak/unlock virtio_gpu_object_array")
---
 drivers/gpu/drm/virtio/virtgpu_gem.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/gpu/drm/virtio/virtgpu_gem.c b/drivers/gpu/drm/virtio/virtgpu_gem.c
index 2de61b63ef91..48d3c9955f0d 100644
--- a/drivers/gpu/drm/virtio/virtgpu_gem.c
+++ b/drivers/gpu/drm/virtio/virtgpu_gem.c
@@ -248,6 +248,9 @@ void virtio_gpu_array_put_free(struct virtio_gpu_object_array *objs)
 {
 	u32 i;
 
+	if (!objs)
+		return;
+
 	for (i = 0; i < objs->nents; i++)
 		drm_gem_object_put(objs->objs[i]);
 	virtio_gpu_array_free(objs);
-- 
2.32.0