Commit de234897 authored Apr 13, 2017 by Max Reitz Committed by Kevin Wolf Apr 27, 2017

block: Do not unref bs->file on error in BD's open



The block layer takes care of removing the bs->file child if the block
driver's bdrv_open()/bdrv_file_open() implementation fails. The block
driver therefore does not need to do so, and indeed should not unless it
sets bs->file to NULL afterwards -- because if this is not done, the
bdrv_unref_child() in bdrv_open_inherit() will dereference the freed
memory block at bs->file afterwards, which is not good.

We can now decide whether to add a "bs->file = NULL;" after each of the
offending bdrv_unref_child() invocations, or just drop them altogether.
The latter is simpler, so let's do that.

Cc: qemu-stable <qemu-stable@nongnu.org>
Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

parent 24dfdfd0

block/blkdebug.c

+1 −3

Original line number	Diff line number	Diff line
		@@ -389,14 +389,12 @@ static int blkdebug_open(BlockDriverState bs, QDict options, int flags,
		} else if (align) {
		error_setg(errp, "Invalid alignment");
		ret = -EINVAL;
		goto fail_unref;
		goto out;
		}

		ret = 0;
		goto out;

		fail_unref:
		bdrv_unref_child(bs, bs->file);
		out:
		if (ret < 0) {
		g_free(s->config_file);

block/blkreplay.c

+0 −3

Original line number	Diff line number	Diff line
		@@ -37,9 +37,6 @@ static int blkreplay_open(BlockDriverState bs, QDict options, int flags,

		ret = 0;
		fail:
		if (ret < 0) {
		bdrv_unref_child(bs, bs->file);
		}
		return ret;
		}

block/blkverify.c

+0 −3

Original line number	Diff line number	Diff line
		@@ -142,9 +142,6 @@ static int blkverify_open(BlockDriverState bs, QDict options, int flags,

		ret = 0;
		fail:
		if (ret < 0) {
		bdrv_unref_child(bs, bs->file);
		}
		qemu_opts_del(opts);
		return ret;
		}