From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:47065) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1g0R7a-0002cR-2L for qemu-devel@nongnu.org; Thu, 13 Sep 2018 08:53:22 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1g0R7U-00029A-VH for qemu-devel@nongnu.org; Thu, 13 Sep 2018 08:53:21 -0400 From: Kevin Wolf Date: Thu, 13 Sep 2018 14:52:12 +0200 Message-Id: <20180913125217.23173-13-kwolf@redhat.com> In-Reply-To: <20180913125217.23173-1-kwolf@redhat.com> References: <20180913125217.23173-1-kwolf@redhat.com> Subject: [Qemu-devel] [PATCH v2 12/17] mirror: Fix potential use-after-free in active commit List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-block@nongnu.org Cc: kwolf@redhat.com, mreitz@redhat.com, famz@redhat.com, pbonzini@redhat.com, slp@redhat.com, jsnow@redhat.com, qemu-devel@nongnu.org When starting an active commit job, other callbacks can run before mirror_start_job() calls bdrv_ref() where needed and cause the nodes to go away. Add another pair of bdrv_ref/unref() around it to protect against this case. Signed-off-by: Kevin Wolf --- block/mirror.c | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/block/mirror.c b/block/mirror.c index 56d9ef7474..c8657991cf 100644 --- a/block/mirror.c +++ b/block/mirror.c @@ -1697,7 +1697,14 @@ void commit_active_start(const char *job_id, BlockDriverState *bs, orig_base_flags = bdrv_get_flags(base); + /* bdrv_reopen() drains, which might make the BDSes go away before a + * reference is taken in mirror_start_job(). */ + bdrv_ref(bs); + bdrv_ref(base); + if (bdrv_reopen(base, bs->open_flags, errp)) { + bdrv_unref(bs); + bdrv_unref(base); return; } @@ -1707,6 +1714,10 @@ void commit_active_start(const char *job_id, BlockDriverState *bs, &commit_active_job_driver, false, base, auto_complete, filter_node_name, false, MIRROR_COPY_MODE_BACKGROUND, &local_err); + + bdrv_unref(bs); + bdrv_unref(base); + if (local_err) { error_propagate(errp, local_err); goto error_restore_flags; -- 2.13.6