UBSAN: shift-out-of-bounds in dbAllocBits

Status: fixed on 2023/06/08 14:41
Subsystems: jfs
[Documentation on labels]
Reported-by: syzbot+b9ba793adebb63e56dba@syzkaller.appspotmail.com
Fix commit: fad376fce0af fs/jfs: fix shift exponent db_agl2size negative
First crash: 1388d, last: 1254d
Cause bisection: failed (error log, bisect log)
  
Fix bisection: fixed by (bisect log) :
commit fad376fce0af58deebc5075b8539dc05bf639af3
Author: Liu Shixin via Jfs-discussion <jfs-discussion@lists.sourceforge.net>
Date: Thu Nov 3 03:01:59 2022 +0000

  fs/jfs: fix shift exponent db_agl2size negative

  
▶ ▼ Discussions (1)
Title Replies (including bot) Last reply
[syzbot] UBSAN: shift-out-of-bounds in dbAllocBits 1 (3) 2023/03/22 21:30
▶ ▼ Fix bisection attempts (3)
Created Duration User Patch Repo Result
2023/03/22 07:51 8h37m bisect fix upstream OK (1) job log
2023/02/20 07:07 43m bisect fix upstream OK (0) job log log
2023/01/21 06:11 36m bisect fix upstream OK (0) job log log

Sample crash report:
loop0: detected capacity change from 0 to 32768
================================================================================
UBSAN: shift-out-of-bounds in fs/jfs/jfs_dmap.c:2217:15
shift exponent -1368651876 is negative
CPU: 0 PID: 3606 Comm: syz-executor109 Not tainted 6.0.0-syzkaller-09039-ga6afa4199d3d #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/22/2022
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x1b1/0x28e lib/dump_stack.c:106
 ubsan_epilogue lib/ubsan.c:151 [inline]
 __ubsan_handle_shift_out_of_bounds+0x33d/0x3b0 lib/ubsan.c:322
 dbAllocBits+0x96f/0x9c0 fs/jfs/jfs_dmap.c:2217
 dbAllocDmap fs/jfs/jfs_dmap.c:1999 [inline]
 dbAllocDmapLev+0x240/0x420 fs/jfs/jfs_dmap.c:1953
 dbAllocCtl+0x113/0x970 fs/jfs/jfs_dmap.c:1793
 dbAllocAny fs/jfs/jfs_dmap.c:1507 [inline]
 dbAlloc+0x5ae/0xc90 fs/jfs/jfs_dmap.c:732
 extBalloc fs/jfs/jfs_extent.c:321 [inline]
 extAlloc+0x4b9/0xff0 fs/jfs/jfs_extent.c:122
 jfs_get_block+0x342/0xce0 fs/jfs/inode.c:248
 __block_write_begin_int+0x5f6/0x1ba0 fs/buffer.c:2006
 __block_write_begin fs/buffer.c:2056 [inline]
 block_write_begin+0x93/0x1e0 fs/buffer.c:2117
 jfs_write_begin+0x2d/0x60 fs/jfs/inode.c:304
 generic_perform_write+0x2a8/0x5b0 mm/filemap.c:3745
 __generic_file_write_iter+0x176/0x400 mm/filemap.c:3873
 generic_file_write_iter+0xab/0x310 mm/filemap.c:3905
 do_iter_write+0x6c2/0xc20 fs/read_write.c:861
 vfs_writev fs/read_write.c:934 [inline]
 do_writev+0x23e/0x430 fs/read_write.c:977
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7fe1ef5c4e39
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:00007fff5e480f98 EFLAGS: 00000246 ORIG_RAX: 0000000000000014
RAX: ffffffffffffffda RBX: 0030656c69662f2e RCX: 00007fe1ef5c4e39
RDX: 0000000000000001 RSI: 0000000020000000 RDI: 0000000000000003
RBP: 00007fe1ef584600 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000f8008000
R13: 0000000000000000 R14: 00080000000000f4 R15: 0000000000000000
 </TASK>
================================================================================

Crashes (4):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2022/10/09 02:28 upstream a6afa4199d3d aea5da89 .config strace log report syz C [disk image] [vmlinux] [mounted in repro] ci2-upstream-fs UBSAN: shift-out-of-bounds in dbAllocBits
2022/11/01 14:54 upstream b229b6ca5abb a1d8560a .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root UBSAN: shift-out-of-bounds in dbAllocBits
2022/11/01 14:47 upstream b229b6ca5abb a1d8560a .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root UBSAN: shift-out-of-bounds in dbAllocBits
2022/10/26 19:12 upstream 4dc12f37a8e9 86777b7f .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs UBSAN: shift-out-of-bounds in dbAllocBits
* Struck through repros no longer work on HEAD.