This is a note to let you know that I've just added the patch titled fs/ntfs3: Avoid UBSAN error on true_sectors_per_clst() to the 6.1-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: fs-ntfs3-avoid-ubsan-error-on-true_sectors_per_clst.patch and it can be found in the queue-6.1 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit 53f0328a1e305e743169b28c6a998adf93e82346 Author: Shigeru Yoshida <syoshida@xxxxxxxxxx> Date: Tue Aug 23 23:46:25 2022 +0900 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 <rdunlap@xxxxxxxxxxxxx> Reported-by: syzbot+35b87c668935bb55e666@xxxxxxxxxxxxxxxxxxxxxxxxx Signed-off-by: Shigeru Yoshida <syoshida@xxxxxxxxxx> Signed-off-by: Konstantin Komarov <almaz.alexandrovich@xxxxxxxxxxxxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> 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; }