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[PATCHv3] videobuf2-core: take mmap_sem before calling __qbuf_userptr

Message ID 53FB24C7.1000408@xs4all.nl (mailing list archive)
State New, archived
Headers show

Commit Message

Hans Verkuil Aug. 25, 2014, 11:57 a.m. UTC 
(Changes since v2: dropped local variable as suggested by Laurent)

Commit f035eb4e976ef5a059e30bc91cfd310ff030a7d3 (videobuf2: fix lockdep warning)
unfortunately removed the mmap_sem lock that is needed around the call to
__qbuf_userptr. Amazingly nobody noticed this (especially me as the author)
until Jan Kara pointed this out to me.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Reported-by: Jan Kara <jack@suse.cz>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
---
 drivers/media/v4l2-core/videobuf2-core.c | 2 ++
 1 file changed, 2 insertions(+)
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Patch

diff --git a/drivers/media/v4l2-core/videobuf2-core.c b/drivers/media/v4l2-core/videobuf2-core.c
index 5b808e2..ce59962b 100644
--- a/drivers/media/v4l2-core/videobuf2-core.c
+++ b/drivers/media/v4l2-core/videobuf2-core.c
@@ -1627,7 +1627,9 @@  static int __buf_prepare(struct vb2_buffer *vb, const struct v4l2_buffer *b)
 		ret = __qbuf_mmap(vb, b);
 		break;
 	case V4L2_MEMORY_USERPTR:
+		down_read(&current->mm->mmap_sem);
 		ret = __qbuf_userptr(vb, b);
+		up_read(&current->mm->mmap_sem);
 		break;
 	case V4L2_MEMORY_DMABUF:
 		ret = __qbuf_dmabuf(vb, b);