From: Max Reitz Date: Sun, 20 Oct 2013 19:52:35 +0000 (+0200) Subject: qcow2: Unset zero_beyond_eof in save_vmstate X-Git-Tag: TizenStudio_2.0_p2.3.2~208^2~1257^2~27 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=6e13610aa454beba52944e8df6d93158d68ab911;p=sdk%2Femulator%2Fqemu.git 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 Reviewed-by: Eric Blake Signed-off-by: Kevin Wolf --- diff --git a/block/qcow2.c b/block/qcow2.c index 4a3e8b4..01269f9 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