From 3ab144fe22a867a0ffcce396302b62b0f2ac4c29 Mon Sep 17 00:00:00 2001 From: Max Reitz Date: Fri, 1 Nov 2013 14:23:16 +0100 Subject: [PATCH 28/81] qcow2: Unset zero_beyond_eof in save_vmstate RH-Author: Max Reitz Message-id: <1383315797-30938-3-git-send-email-mreitz@redhat.com> Patchwork-id: 55217 O-Subject: [RHEL-7.0 qemu-kvm PATCH 2/3] qcow2: Unset zero_beyond_eof in save_vmstate Bugzilla: 1025740 RH-Acked-by: Kevin Wolf RH-Acked-by: Stefan Hajnoczi RH-Acked-by: Alex Williamson BZ: 1025740 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 Reviewed-by: Eric Blake Signed-off-by: Kevin Wolf (cherry picked from commit 6e13610aa454beba52944e8df6d93158d68ab911) Signed-off-by: Max Reitz --- block/qcow2.c | 3 +++ 1 file changed, 3 insertions(+) Signed-off-by: Miroslav Rezanina --- block/qcow2.c | 3 +++ 1 files changed, 3 insertions(+), 0 deletions(-) diff --git a/block/qcow2.c b/block/qcow2.c index f4adf35..c2728c9 100644 --- a/block/qcow2.c +++ b/block/qcow2.c @@ -1718,12 +1718,15 @@ 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 -- 1.7.1