Commit 6e13610a authored by Max Reitz's avatar Max Reitz Committed by Kevin Wolf
Browse files

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: default avatarMax Reitz <mreitz@redhat.com>
Reviewed-by: default avatarEric Blake <eblake@redhat.com>
Signed-off-by: default avatarKevin Wolf <kwolf@redhat.com>
parent eedff66f

block/qcow2.c

+3 −0
Original line number Diff line number Diff line
@@ -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