linux-kernel - [PATCH 4.14 42/59] media: vb2: vb2

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20190121122501.463503857@linuxfoundation.org>
Date:   Mon, 21 Jan 2019 14:44:07 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Hans Verkuil <hverkuil@...all.nl>,
        syzbot+be93025dd45dccd8923c@...kaller.appspotmail.com,
        Hans Verkuil <hansverk@...co.com>,
        Mauro Carvalho Chehab <mchehab+samsung@...nel.org>
Subject: [PATCH 4.14 42/59] media: vb2: vb2_mmap: move lock up

4.14-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Hans Verkuil <hverkuil@...all.nl>

commit cd26d1c4d1bc947b56ae404998ae2276df7b39b7 upstream.

If a filehandle is dup()ped, then it is possible to close it from one fd
and call mmap from the other. This creates a race condition in vb2_mmap
where it is using queue data that __vb2_queue_free (called from close())
is in the process of releasing.

By moving up the mutex_lock(mmap_lock) in vb2_mmap this race is avoided
since __vb2_queue_free is called with the same mutex locked. So vb2_mmap
now reads consistent buffer data.

Signed-off-by: Hans Verkuil <hverkuil@...all.nl>
Reported-by: syzbot+be93025dd45dccd8923c@...kaller.appspotmail.com
Signed-off-by: Hans Verkuil <hansverk@...co.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@...nel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/media/v4l2-core/videobuf2-core.c |   11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

--- a/drivers/media/v4l2-core/videobuf2-core.c
+++ b/drivers/media/v4l2-core/videobuf2-core.c
@@ -1925,9 +1925,13 @@ int vb2_mmap(struct vb2_queue *q, struct
 			return -EINVAL;
 		}
 	}
+
+	mutex_lock(&q->mmap_lock);
+
 	if (vb2_fileio_is_active(q)) {
 		dprintk(1, "mmap: file io in progress\n");
-		return -EBUSY;
+		ret = -EBUSY;
+		goto unlock;
 	}
 
 	/*
@@ -1935,7 +1939,7 @@ int vb2_mmap(struct vb2_queue *q, struct
 	 */
 	ret = __find_plane_by_offset(q, off, &buffer, &plane);
 	if (ret)
-		return ret;
+		goto unlock;
 
 	vb = q->bufs[buffer];
 
@@ -1951,8 +1955,9 @@ int vb2_mmap(struct vb2_queue *q, struct
 		return -EINVAL;
 	}
 
-	mutex_lock(&q->mmap_lock);
 	ret = call_memop(vb, mmap, vb->planes[plane].mem_priv, vma);
+
+unlock:
 	mutex_unlock(&q->mmap_lock);
 	if (ret)
 		return ret;