lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  linux-hardening  PHC 
Open Source and information security mailing list archives
Hash Suite for Android: free password hash cracker in your pocket
[<prev] [next>] [day] [month] [year] [list]
Date:   Mon, 01 Feb 2021 01:16:11 -0800
From:   syzbot <>
Subject: UBSAN: shift-out-of-bounds in ext4_mb_init


syzbot found the following issue on:

HEAD commit:    6642d600 Merge tag '5.11-rc5-smb3' of git://
git tree:       upstream
console output:
kernel config:
dashboard link:
compiler:       clang version 11.0.1
syz repro:
C reproducer:

The issue was bisected to:

commit cfd73237722135807967f389bcbda558a60a30d6
Author: Alex Zhuravlev <>
Date:   Tue Apr 21 07:54:07 2020 +0000

    ext4: add prefetching for block allocation bitmaps

bisection log:
final oops:
console output:

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Fixes: cfd732377221 ("ext4: add prefetching for block allocation bitmaps")

loop0: detected capacity change from 264192 to 0
UBSAN: shift-out-of-bounds in fs/ext4/mballoc.c:2713:24
shift exponent 60 is too large for 32-bit type 'int'
CPU: 1 PID: 8433 Comm: syz-executor484 Not tainted 5.11.0-rc5-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:79 [inline]
 dump_stack+0x137/0x1be lib/dump_stack.c:120
 ubsan_epilogue lib/ubsan.c:148 [inline]
 __ubsan_handle_shift_out_of_bounds+0x432/0x4d0 lib/ubsan.c:395
 ext4_mb_init_backend fs/ext4/mballoc.c:2713 [inline]
 ext4_mb_init+0x19bc/0x19f0 fs/ext4/mballoc.c:2898
 ext4_fill_super+0xc2ec/0xfbe0 fs/ext4/super.c:4983
 mount_bdev+0x26c/0x3a0 fs/super.c:1366
 legacy_get_tree+0xea/0x180 fs/fs_context.c:592
 vfs_get_tree+0x86/0x270 fs/super.c:1496
 do_new_mount fs/namespace.c:2881 [inline]
 path_mount+0x17ad/0x2a00 fs/namespace.c:3211
 do_mount fs/namespace.c:3224 [inline]
 __do_sys_mount fs/namespace.c:3432 [inline]
 __se_sys_mount+0x28c/0x320 fs/namespace.c:3409
 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
RIP: 0033:0x44710a
Code: b8 08 00 00 00 0f 05 48 3d 01 f0 ff ff 0f 83 fd ad fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 49 89 ca b8 a5 00 00 00 0f 05 <48> 3d 01 f0 ff ff 0f 83 da ad fb ff c3 66 0f 1f 84 00 00 00 00 00
RSP: 002b:00007ffc5b95ff48 EFLAGS: 00000206 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007ffc5b95ffa0 RCX: 000000000044710a
RDX: 0000000020000000 RSI: 0000000020000180 RDI: 00007ffc5b95ff60
RBP: 00007ffc5b95ff60 R08: 00007ffc5b95ffa0 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000000013
R13: 0000000000000004 R14: 0000000000000003 R15: 0000000000000003

This report is generated by a bot. It may contain errors.
See for more information about syzbot.
syzbot engineers can be reached at

syzbot will keep track of this issue. See: for how to communicate with syzbot.
For information about bisection process see:
syzbot can test patches for this issue, for details see:

Powered by blists - more mailing lists