@@ -2120,9 +2120,13 @@ int vb2_mmap(struct vb2_queue *q, struct vm_area_struct *vma)
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;
}
/*
@@ -2130,7 +2134,7 @@ int vb2_mmap(struct vb2_queue *q, struct vm_area_struct *vma)
*/
ret = __find_plane_by_offset(q, off, &buffer, &plane);
if (ret)
- return ret;
+ goto unlock;
vb = q->bufs[buffer];
@@ -2146,8 +2150,9 @@ int vb2_mmap(struct vb2_queue *q, struct vm_area_struct *vma)
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;
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@xs4all.nl> Reported-by: syzbot+be93025dd45dccd8923c@syzkaller.appspotmail.com --- drivers/media/common/videobuf2/videobuf2-core.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-)