[media] vb2: core: Skip planes array verification if pb is NULL

An earlier patch fixing an input validation issue introduced another
issue: vb2_core_dqbuf() is called with pb argument value NULL in some
cases, causing a NULL pointer dereference. Fix this by skipping the
verification as there's nothing to verify.

Fixes: e7e0c3e26587 ("[media] videobuf2-core: Check user space planes array in dqbuf")

Signed-off-by: David R <david@unsolicited.net>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Reviewed-by: Hans Verkuil <hans.verkuil@cisco.com>
Cc: stable@vger.kernel.org # for v4.4 and later
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>

1 files changed, 6 insertions, 4 deletions

diff --git a/drivers/media/v4l2-core/videobuf2-core.c b/drivers/media/v4l2-core/videobuf2-core.c
index 9fbcb67a9ee6..633fc1ab1d7a 100644
--- a/drivers/media/v4l2-core/videobuf2-core.c
+++ b/drivers/media/v4l2-core/videobuf2-core.c
@@ -1648,7 +1648,7 @@ static int __vb2_get_done_vb(struct vb2_queue *q, struct vb2_buffer **vb,
                              void *pb, int nonblocking)
 {
         unsigned long flags;
-        int ret;
+        int ret = 0;
 
         /*
          * Wait for at least one buffer to become available on the done_list.
@@ -1664,10 +1664,12 @@ static int __vb2_get_done_vb(struct vb2_queue *q, struct vb2_buffer **vb,
         spin_lock_irqsave(&q->done_lock, flags);
         *vb = list_first_entry(&q->done_list, struct vb2_buffer, done_entry);
         /*
-         * Only remove the buffer from done_list if v4l2_buffer can handle all
-         * the planes.
+         * Only remove the buffer from done_list if all planes can be
+         * handled. Some cases such as V4L2 file I/O and DVB have pb
+         * == NULL; skip the check then as there's nothing to verify.
          */
-        ret = call_bufop(q, verify_planes_array, *vb, pb);
+        if (pb)
+                ret = call_bufop(q, verify_planes_array, *vb, pb);
         if (!ret)
                 list_del(&(*vb)->done_entry);
         spin_unlock_irqrestore(&q->done_lock, flags);