block: fix null-pointer bug on error case in block commit

This is a bug that was caught by a coverity run by Markus.  In
the error case when we errored out to exit_restore_open early in the
function, 'overlay_bs' was still NULL at that point, although it is
used to look up flags and perform a bdrv_reopen().

Move the overlay_bs lookup to where it is needed, and check for NULL
before restoring the flags.  Also get rid of the unneeded parameter
initialization.

Reported-By: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Jeff Cody <jcody@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
This commit is contained in:
Jeff Cody 2013-01-15 10:47:24 -05:00 committed by Stefan Hajnoczi
parent 47f4dac3fd
commit 6d759117d3

View File

@ -65,7 +65,7 @@ static void coroutine_fn commit_run(void *opaque)
BlockDriverState *active = s->active;
BlockDriverState *top = s->top;
BlockDriverState *base = s->base;
BlockDriverState *overlay_bs = NULL;
BlockDriverState *overlay_bs;
int64_t sector_num, end;
int ret = 0;
int n = 0;
@ -92,8 +92,6 @@ static void coroutine_fn commit_run(void *opaque)
}
}
overlay_bs = bdrv_find_overlay(active, top);
end = s->common.len >> BDRV_SECTOR_BITS;
buf = qemu_blockalign(top, COMMIT_BUFFER_SIZE);
@ -156,7 +154,8 @@ exit_restore_reopen:
if (s->base_flags != bdrv_get_flags(base)) {
bdrv_reopen(base, s->base_flags, NULL);
}
if (s->orig_overlay_flags != bdrv_get_flags(overlay_bs)) {
overlay_bs = bdrv_find_overlay(active, top);
if (overlay_bs && s->orig_overlay_flags != bdrv_get_flags(overlay_bs)) {
bdrv_reopen(overlay_bs, s->orig_overlay_flags, NULL);
}