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mirror: Make sure that source and target size match

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If the target is shorter than the source, mirror would copy data until
it reaches the end of the target and then fail with an I/O error when
trying to write past the end.

If the target is longer than the source, the mirror job would complete
successfully, but the target wouldn't actually be an accurate copy of
the source image (it would contain some additional garbage at the end).

Fix this by checking that both images have the same size when the job
starts.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-Id: <20200511135825.219437-4-kwolf@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Kevin Wolf 2020-05-11 15:58:24 +02:00
parent d89ac3cf30
commit e83dd6808c
1 changed files with 12 additions and 9 deletions
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21
block/mirror.c
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@ -872,6 +872,7 @@ static int coroutine_fn mirror_run(Job *job, Error **errp)
BlockDriverState *target_bs = blk_bs(s->target); BlockDriverState *target_bs = blk_bs(s->target);
bool need_drain = true; bool need_drain = true;
int64_t length; int64_t length;
int64_t target_length;
BlockDriverInfo bdi; BlockDriverInfo bdi;
char backing_filename[2]; /* we only need 2 characters because we are only char backing_filename[2]; /* we only need 2 characters because we are only
checking for a NULL string */ checking for a NULL string */
@ -887,24 +888,26 @@ static int coroutine_fn mirror_run(Job *job, Error **errp)
goto immediate_exit; goto immediate_exit;
} }
target_length = blk_getlength(s->target);
if (target_length < 0) {
ret = target_length;
goto immediate_exit;
}
/* Active commit must resize the base image if its size differs from the /* Active commit must resize the base image if its size differs from the
* active layer. */ * active layer. */
if (s->base == blk_bs(s->target)) { if (s->base == blk_bs(s->target)) {
int64_t base_length; if (s->bdev_length > target_length) {
base_length = blk_getlength(s->target);
if (base_length < 0) {
ret = base_length;
goto immediate_exit;
}
if (s->bdev_length > base_length) {
ret = blk_truncate(s->target, s->bdev_length, false, ret = blk_truncate(s->target, s->bdev_length, false,
PREALLOC_MODE_OFF, 0, NULL); PREALLOC_MODE_OFF, 0, NULL);
if (ret < 0) { if (ret < 0) {
goto immediate_exit; goto immediate_exit;
} }
} }
} else if (s->bdev_length != target_length) {
error_setg(errp, "Source and target image have different sizes");
ret = -EINVAL;
goto immediate_exit;
} }
if (s->bdev_length == 0) { if (s->bdev_length == 0) {