linux-kernel - [PATCH v2] ocfs2: Fix shift-out-of-bounds UBSAN bug in ocfs2_verify

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Message-ID: <ZsPvwQAXd5R/jNY+@hostname>
Date: Tue, 20 Aug 2024 02:22:09 +0100
From: qasdev <qasdev00@...il.com>
To: mark@...heh.com, jlbec@...lplan.org, joseph.qi@...ux.alibaba.com
Cc: ocfs2-devel@...ts.linux.dev, linux-kernel@...r.kernel.org
Subject: [PATCH v2] ocfs2: Fix shift-out-of-bounds UBSAN bug in
 ocfs2_verify_volume()

This patch addresses a shift-out-of-bounds error in the
ocfs2_verify_volume() function, identified by UBSAN. The bug was triggered
by an invalid s_clustersize_bits value (e.g., 1548), which caused the
expression "1 << le32_to_cpu(di->id2.i_super.s_clustersize_bits)"
to exceed the limits of a 32-bit integer,
leading to an out-of-bounds shift.

Reported-by: syzbot <syzbot+f3fff775402751ebb471@...kaller.appspotmail.com>
Closes: https://syzkaller.appspot.com/bug?extid=f3fff775402751ebb471
Tested-by: syzbot <syzbot+f3fff775402751ebb471@...kaller.appspotmail.com>
Signed-off-by: Qasim Ijaz <qasdev00@...il.com>
---
 fs/ocfs2/super.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/ocfs2/super.c b/fs/ocfs2/super.c
index afee70125ae3..b704983b2112 100644
--- a/fs/ocfs2/super.c
+++ b/fs/ocfs2/super.c
@@ -2357,8 +2357,8 @@ static int ocfs2_verify_volume(struct ocfs2_dinode *di,
 			     (unsigned long long)bh->b_blocknr);
 		} else if (le32_to_cpu(di->id2.i_super.s_clustersize_bits) < 12 ||
 			    le32_to_cpu(di->id2.i_super.s_clustersize_bits) > 20) {
-			mlog(ML_ERROR, "bad cluster size found: %u\n",
-			     1 << le32_to_cpu(di->id2.i_super.s_clustersize_bits));
+			mlog(ML_ERROR, "bad cluster size bit found: %u\n",
+			     le32_to_cpu(di->id2.i_super.s_clustersize_bits));
 		} else if (!le64_to_cpu(di->id2.i_super.s_root_blkno)) {
 			mlog(ML_ERROR, "bad root_blkno: 0\n");
 		} else if (!le64_to_cpu(di->id2.i_super.s_system_dir_blkno)) {
-- 
2.30.2