[PATCH] media: fix null pointer dereference in v4l_vb2q_enable_media_source()

[Shuah Khan]

Fix the null pointer dereference in v4l_vb2q_enable_media_source().
DVB only drivers don't have valid struct v4l2_fh pointer.

[  548.443272] BUG: unable to handle kernel NULL pointer dereference
at 0000000000000010
[  548.452036] IP: [<ffffffffc020ffc9>]
v4l_vb2q_enable_media_source+0x9/0x50 [videodev]
[  548.460792] PGD b820e067 PUD bb3df067 PMD 0
[  548.465582] Oops: 0000 [#1] SMP

Signed-off-by: Shuah Khan <shuahkh@xxxxxxxxxxxxxxx>
Reported-by: Olli Salonen <olli.salonen@xxxxxx>
---
 drivers/media/v4l2-core/v4l2-mc.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/media/v4l2-core/v4l2-mc.c b/drivers/media/v4l2-core/v4l2-mc.c
index 643686d..a39a3cd 100644
--- a/drivers/media/v4l2-core/v4l2-mc.c
+++ b/drivers/media/v4l2-core/v4l2-mc.c
@@ -214,6 +214,8 @@ int v4l_vb2q_enable_media_source(struct vb2_queue *q)
 {
 	struct v4l2_fh *fh = q->owner;
 
-	return v4l_enable_media_source(fh->vdev);
+	if (fh && fh->vdev)
+		return v4l_enable_media_source(fh->vdev);
+	return 0;
 }
 EXPORT_SYMBOL_GPL(v4l_vb2q_enable_media_source);
-- 
2.5.0