From: Shigeru Yoshida Date: Tue, 23 Aug 2022 14:46:25 +0000 (+0900) Subject: fs/ntfs3: Avoid UBSAN error on true_sectors_per_clst() X-Git-Tag: v5.15.92~942 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=4b51f27d4448c84957bce190292f75d4896d56b3;p=platform%2Fkernel%2Flinux-rpi.git fs/ntfs3: Avoid UBSAN error on true_sectors_per_clst() [ Upstream commit caad9dd8792a2622737b7273cb34835fd9536cd2 ] 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 Reported-by: syzbot+35b87c668935bb55e666@syzkaller.appspotmail.com Signed-off-by: Shigeru Yoshida Signed-off-by: Konstantin Komarov Signed-off-by: Sasha Levin --- diff --git a/fs/ntfs3/super.c b/fs/ntfs3/super.c index f3b88c7..39b09f3 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; }