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| author | Hans Verkuil <hverkuil@xs4all.nl> | 2018-11-13 17:06:46 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-01-23 10:10:55 +0300 |
| commit | e89662f06a17ff0cfc2037d397683df04d95905f (patch) | |
| tree | 3dc833e2350ba39daf585b05d5b7dbaa696ed0f0 /drivers/media | |
| parent | a017e3968242552056ffeb9e803a8d9650c40159 (diff) | |
| download | linux-e89662f06a17ff0cfc2037d397683df04d95905f.tar.xz | |
media: vb2: vb2_mmap: move lock up
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@xs4all.nl>
Reported-by: syzbot+be93025dd45dccd8923c@syzkaller.appspotmail.com
Signed-off-by: Hans Verkuil <hansverk@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/media')
| -rw-r--r-- | drivers/media/v4l2-core/videobuf2-core.c | 11 |
1 files changed, 8 insertions, 3 deletions
diff --git a/drivers/media/v4l2-core/videobuf2-core.c b/drivers/media/v4l2-core/videobuf2-core.c index 4df4a1f402be..fa970650e913 100644 --- a/drivers/media/v4l2-core/videobuf2-core.c +++ b/drivers/media/v4l2-core/videobuf2-core.c @@ -1916,9 +1916,13 @@ 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; } /* @@ -1926,7 +1930,7 @@ 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]; @@ -1942,8 +1946,9 @@ 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; |