linux-kernel - [PATCH 5.9 706/757] xfs: make sure the rt allocator doesnt run off the end

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20201027135523.621223082@linuxfoundation.org>
Date:   Tue, 27 Oct 2020 14:55:56 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        "Darrick J. Wong" <darrick.wong@...cle.com>,
        Christoph Hellwig <hch@....de>, Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.9 706/757] xfs: make sure the rt allocator doesnt run off the end

From: Darrick J. Wong <darrick.wong@...cle.com>

[ Upstream commit 2a6ca4baed620303d414934aa1b7b0a8e7bab05f ]

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@...cle.com>
Reviewed-by: Christoph Hellwig <hch@....de>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 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 6209e7b6b895b..86994d7f7cba3 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.
 	 */
-- 
2.25.1