From 6e13610aa454beba52944e8df6d93158d68ab911 Mon Sep 17 00:00:00 2001
From: Max Reitz <mreitz@redhat.com>
Date: Sun, 20 Oct 2013 21:52:35 +0200
Subject: [PATCH] qcow2: Unset zero_beyond_eof in save_vmstate
Saving the VM state is done using bdrv_pwrite. This function may perform
a read-modify-write, which in this case results in data being read from
beyond the end of the virtual disk. Since we are actually trying to
access an area which is not a part of the virtual disk, zero_beyond_eof
has to be set to false before performing the partial write, otherwise
the VM state may become corrupted.
Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
block/qcow2.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/block/qcow2.c b/block/qcow2.c
index 4a3e8b45f8..01269f9264 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -1941,12 +1941,15 @@ static int qcow2_save_vmstate(BlockDriverState *bs, QEMUIOVector *qiov,
BDRVQcowState *s = bs->opaque;
int64_t total_sectors = bs->total_sectors;
int growable = bs->growable;
+ bool zero_beyond_eof = bs->zero_beyond_eof;
int ret;
BLKDBG_EVENT(bs->file, BLKDBG_VMSTATE_SAVE);
bs->growable = 1;
+ bs->zero_beyond_eof = false;
ret = bdrv_pwritev(bs, qcow2_vm_state_offset(s) + pos, qiov);
bs->growable = growable;
+ bs->zero_beyond_eof = zero_beyond_eof;
/* bdrv_co_do_writev will have increased the total_sectors value to include
* the VM state - the VM state is however not an actual part of the block
--
2.30.2