From: Shigeru Yoshida <syoshida@redhat.com>
To: almaz.alexandrovich@paragon-software.com
Cc: ntfs3@lists.linux.dev, linux-kernel@vger.kernel.org,
Shigeru Yoshida <syoshida@redhat.com>,
"Author : Randy Dunlap" <rdunlap@infradead.org>,
syzbot+35b87c668935bb55e666@syzkaller.appspotmail.com
Subject: [PATCH] fs/ntfs3: Avoid UBSAN error on true_sectors_per_clst()
Date: Tue, 23 Aug 2022 23:46:25 +0900 [thread overview]
Message-ID: <20220823144625.1627736-1-syoshida@redhat.com> (raw)
syzbot reported UBSAN error as below:
[ 76.901829][ T6677] ================================================================================
[ 76.903908][ T6677] UBSAN: shift-out-of-bounds in fs/ntfs3/super.c:675:13
[ 76.905363][ T6677] shift exponent -247 is negative
This patch avoid this error.
Link: https://syzkaller.appspot.com/bug?id=b0299c09a14aababf0f1c862dd4ebc8ab9eb0179
Fixes: a3b774342fa7 (fs/ntfs3: validate BOOT sectors_per_clusters)
Cc: Author: Randy Dunlap <rdunlap@infradead.org>
Reported-by: syzbot+35b87c668935bb55e666@syzkaller.appspotmail.com
Signed-off-by: Shigeru Yoshida <syoshida@redhat.com>
---
fs/ntfs3/super.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/fs/ntfs3/super.c b/fs/ntfs3/super.c
index 47012c9bf505..adc4f73722b7 100644
--- a/fs/ntfs3/super.c
+++ b/fs/ntfs3/super.c
@@ -672,7 +672,7 @@ static u32 true_sectors_per_clst(const struct NTFS_BOOT *boot)
if (boot->sectors_per_clusters <= 0x80)
return boot->sectors_per_clusters;
if (boot->sectors_per_clusters >= 0xf4) /* limit shift to 2MB max */
- return 1U << (0 - boot->sectors_per_clusters);
+ return 1U << -(s8)boot->sectors_per_clusters;
return -EINVAL;
}
--
2.37.2
next reply other threads:[~2022-08-23 14:46 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-08-23 14:46 Shigeru Yoshida [this message]
2022-09-07 16:01 ` [PATCH] fs/ntfs3: Avoid UBSAN error on true_sectors_per_clst() Shigeru Yoshida
2022-09-30 15:53 ` Konstantin Komarov
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