From: Remington Brasga <rbrasga@uci.edu>
To: Dave Kleikamp <shaggy@kernel.org>,
Manas Ghandat <ghandatmanas@gmail.com>,
Juntong Deng <juntong.deng@outlook.com>,
Andrew Kanner <andrew.kanner@gmail.com>,
Osama Muhammad <osmtendev@gmail.com>,
Shuah Khan <skhan@linuxfoundation.org>
Cc: jfs-discussion@lists.sourceforge.net,
linux-kernel@vger.kernel.org,
linux-kernel-mentees@lists.linuxfoundation.org,
syzbot+e38d703eeb410b17b473@syzkaller.appspotmail.com,
Remington Brasga <rbrasga@uci.edu>
Subject: [PATCH] jfs: UBSAN: shift-out-of-bounds in dbFindBits
Date: Wed, 10 Jul 2024 00:12:44 +0000 [thread overview]
Message-ID: <20240710001244.2707-1-rbrasga@uci.edu> (raw)
Fix issue with UBSAN throwing shift-out-of-bounds warning.
Reported-by: syzbot+e38d703eeb410b17b473@syzkaller.appspotmail.com
Signed-off-by: Remington Brasga <rbrasga@uci.edu>
---
When nb = 32, `mask = mask >> nb` or shorthand `mask >>= nb` throws
shift-out-of-bounds warning.
`mask = (mask >> nb)` removes that warning.
Link to the syzbot bug report: https://lore.kernel.org/all/0000000000006fc563061cbc7f9c@google.com/T/
fs/jfs/jfs_dmap.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/fs/jfs/jfs_dmap.c b/fs/jfs/jfs_dmap.c
index cb3cda1390ad..636aae946e84 100644
--- a/fs/jfs/jfs_dmap.c
+++ b/fs/jfs/jfs_dmap.c
@@ -3020,7 +3020,7 @@ static int dbFindBits(u32 word, int l2nb)
/* scan the word for nb free bits at nb alignments.
*/
- for (bitno = 0; mask != 0; bitno += nb, mask >>= nb) {
+ for (bitno = 0; mask != 0; bitno += nb, mask = (mask >> nb)) {
if ((mask & word) == mask)
break;
}
--
2.34.1
next reply other threads:[~2024-07-10 0:13 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-07-10 0:12 Remington Brasga [this message]
2024-08-23 18:16 ` [PATCH] jfs: UBSAN: shift-out-of-bounds in dbFindBits Dave Kleikamp
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