From 2a6ca4baed620303d414934aa1b7b0a8e7bab05f Mon Sep 17 00:00:00 2001
From: "Darrick J. Wong" <darrick.wong@oracle.com>
Date: Wed, 9 Sep 2020 14:21:06 -0700
Subject: [PATCH] xfs: make sure the rt allocator doesn't run off the end
Git-commit: 2a6ca4baed620303d414934aa1b7b0a8e7bab05f
Patch-mainline: v5.10-rc1
References: git-fixes
There's an overflow bug in the realtime allocator. If the rt volume is
large enough to handle a single allocation request that is larger than
the maximum bmap extent length and the rt bitmap ends exactly on a
bitmap block boundary, it's possible that the near allocator will try to
check the freeness of a range that extends past the end of the bitmap.
This fails with a corruption error and shuts down the fs.
Therefore, constrain maxlen so that the range scan cannot run off the
end of the rt bitmap.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Acked-by: Anthony Iliopoulos <ailiop@suse.com>
---
fs/xfs/xfs_rtalloc.c | 11 +++++++++++
1 file changed, 11 insertions(+)
diff --git a/fs/xfs/xfs_rtalloc.c b/fs/xfs/xfs_rtalloc.c
index 0558f92ecdb8..5b89c12f1566 100644
--- a/fs/xfs/xfs_rtalloc.c
+++ b/fs/xfs/xfs_rtalloc.c
@@ -247,6 +247,9 @@ xfs_rtallocate_extent_block(
end = XFS_BLOCKTOBIT(mp, bbno + 1) - 1;
i <= end;
i++) {
+ /* Make sure we don't scan off the end of the rt volume. */
+ maxlen = min(mp->m_sb.sb_rextents, i + maxlen) - i;
+
/*
* See if there's a free extent of maxlen starting at i.
* If it's not so then next will contain the first non-free.
@@ -442,6 +445,14 @@ xfs_rtallocate_extent_near(
*/
if (bno >= mp->m_sb.sb_rextents)
bno = mp->m_sb.sb_rextents - 1;
+
+ /* Make sure we don't run off the end of the rt volume. */
+ maxlen = min(mp->m_sb.sb_rextents, bno + maxlen) - bno;
+ if (maxlen < minlen) {
+ *rtblock = NULLRTBLOCK;
+ return 0;
+ }
+
/*
* Try the exact allocation first.
*/
--
2.35.3