xfs: fix uninitialized variable access

mainline inclusion
from mainline-v6.2-rc6
commit 60b730a4
category: bugfix
bugzilla: 188220, https://gitee.com/openeuler/kernel/issues/I4KIAO

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=60b730a40c43fbcc034970d3e77eb0f25b8cc1cf

--------------------------------

If the end position of a GETFSMAP query overlaps an allocated space and
we're using the free space info to generate fsmap info, the akeys
information gets fed into the fsmap formatter with bad results.
Zero-init the space.

Reported-by: syzbot+090ae72d552e6bd93cfe@syzkaller.appspotmail.com
Signed-off-by: NDarrick J. Wong <djwong@kernel.org>
Signed-off-by: NLong Li <leo.lilong@huawei.com>
(cherry picked from commit aebc38d3)

fs/xfs/xfs_fsmap.c

@@ -746,6 +746,7 @@ xfs_getfsmap_datadev_bnobt(
 {
 	struct xfs_alloc_rec_incore	akeys[2];
 
+	memset(akeys, 0, sizeof(akeys));
 	info->missing_owner = XFS_FMR_OWN_UNKNOWN;
 	return __xfs_getfsmap_datadev(tp, keys, info,
 			xfs_getfsmap_datadev_bnobt_query, &akeys[0]);