From: Kevin Wolf <kwolf@redhat.com>
Date: Mon, 14 Jan 2013 16:31:31 +0000 (+0100)
Subject: qcow2: Fix segfault on zero-length write
X-Git-Tag: qemu-xen-4.4.0-rc1~6^2~1400^2~14
X-Git-Url: http://xenbits.xensource.com/gitweb?a=commitdiff_plain;h=8d2497c3552e19a60e7a75d20976471ecb2a8e2b;p=qemu-upstream-4.5-testing.git

qcow2: Fix segfault on zero-length write

One of the recent refactoring patches (commit f50f88b9) didn't take care
to initialise l2meta properly, so with zero-length writes, which don't
even enter the write loop, qemu just segfaulted.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
---

diff --git a/block/qcow2.c b/block/qcow2.c
index d603f98a9..f6abff611 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -759,7 +759,7 @@ static coroutine_fn int qcow2_co_writev(BlockDriverState *bs,
     QEMUIOVector hd_qiov;
     uint64_t bytes_done = 0;
     uint8_t *cluster_data = NULL;
-    QCowL2Meta *l2meta;
+    QCowL2Meta *l2meta = NULL;
 
     trace_qcow2_writev_start_req(qemu_coroutine_self(), sector_num,
                                  remaining_sectors);