syzbot


UBSAN: shift-out-of-bounds in minix_count_free_blocks

Status: upstream: reported C repro on 2022/02/24 22:40
Reported-by: syzbot+2f142b57f2af27974fda@syzkaller.appspotmail.com
First crash: 216d, last: 52d

Cause bisection: the issue happens on the oldest tested release (bisect log)
Crash: UBSAN: shift-out-of-bounds in minix_count_free_blocks (log)
Repro: C syz .config

Fix bisection: the fix commit could be any of (bisect log):
  e8a4e1c1bb69 Merge tag 'loongarch-fixes-5.19-4' of git://git.kernel.org/pub/scm/linux/kernel/git/chenhuacai/linux-loongson
  1612c382ffbd Merge tag 'x86-urgent-2022-08-06' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Patch testing requests:
Created Duration User Patch Repo Result
2022/05/10 02:55 8m wanngchenng@gmail.com https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/ master report log
2022/05/01 01:40 8m (218) wanngchenng@gmail.com https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/ master report log
2022/04/30 10:12 10m (218) wanngchenng@gmail.com https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/ master report log

Sample crash report:
MINIX-fs: mounting unchecked file system, running fsck is recommended
================================================================================
UBSAN: shift-out-of-bounds in fs/minix/bitmap.c:103:3
shift exponent 34 is too large for 32-bit type 'unsigned int'
CPU: 1 PID: 3602 Comm: syz-executor385 Not tainted 5.19.0-syzkaller-02972-g200e340f2196 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/22/2022
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106
 ubsan_epilogue+0xb/0x50 lib/ubsan.c:151
 __ubsan_handle_shift_out_of_bounds.cold+0xb1/0x187 lib/ubsan.c:322
 minix_count_free_blocks.cold+0x16/0x1b fs/minix/bitmap.c:103
 minix_statfs+0x22a/0x490 fs/minix/inode.c:381
 statfs_by_dentry+0x133/0x210 fs/statfs.c:66
 vfs_statfs fs/statfs.c:90 [inline]
 user_statfs+0xa9/0x160 fs/statfs.c:105
 __do_sys_statfs+0x7a/0xf0 fs/statfs.c:195
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f23cb13ddc9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 c0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffc64bc7b38 EFLAGS: 00000246 ORIG_RAX: 0000000000000089
RAX: ffffffffffffffda RBX: 0030656c69662f2e RCX: 00007f23cb13ddc9
RDX: 00007f23cb0fc2f3 RSI: 0000000000000000 RDI: 0000000020000140
RBP: 00007f23cb0fd5c0 R08: 0000000000000000 R09: 0000000000000000
R10: 00007ffc64bc7a00 R11: 0000000000000246 R12: 00007f23cb0fd650
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
 </TASK>
================================================================================

Crashes (6):
Manager Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Title
ci-upstream-kasan-gce-selinux-root 2022/08/07 05:45 upstream 200e340f2196 88e3a122 .config log report syz C UBSAN: shift-out-of-bounds in minix_count_free_blocks
ci-upstream-kasan-gce-smack-root 2022/07/08 05:42 upstream e8a4e1c1bb69 bff65f44 .config log report syz C UBSAN: shift-out-of-bounds in minix_count_free_blocks
ci-upstream-kasan-gce-root 2022/02/24 08:42 upstream 23d04328444a 6e821dbf .config log report syz C UBSAN: shift-out-of-bounds in minix_count_free_blocks
ci-upstream-linux-next-kasan-gce-root 2022/07/05 02:06 linux-next cb71b93c2dc3 bff65f44 .config log report syz C UBSAN: shift-out-of-bounds in minix_count_free_blocks
ci-upstream-kasan-gce-root 2022/02/24 08:28 upstream 23d04328444a 6e821dbf .config log report info UBSAN: shift-out-of-bounds in minix_count_free_blocks
ci-qemu-upstream-386 2022/02/24 08:42 upstream 23d04328444a 6e821dbf .config log report info UBSAN: shift-out-of-bounds in minix_count_free_blocks
* Struck through repros no longer work on HEAD.