Re: [syzbot] [jfs?] UBSAN: array-index-out-of-bounds in diAllocBit

[syzbot <syzbot+015483fc71d1413f40ee@syzkaller.appspotmail.com>]

syzbot has found a reproducer for the following issue on:

HEAD commit:    390d73adf896 Merge tag 'for-v7.2' of git://git.kernel.org/..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=12675b7a580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=569f5d5519e8bac8
dashboard link: https://syzkaller.appspot.com/bug?extid=015483fc71d1413f40ee
compiler:       Debian clang version 22.1.6 (++20260514074242+fc4aad7b5db3-1~exp1~20260514074407.73), Debian LLD 22.1.6
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=1150cd56580000

Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/d900f083ada3/non_bootable_disk-390d73ad.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/3cb386497ebc/vmlinux-390d73ad.xz
kernel image: https://storage.googleapis.com/syzbot-assets/333ffabcead8/bzImage-390d73ad.xz
mounted in repro #1: https://storage.googleapis.com/syzbot-assets/eb5e24fa41f8/mount_0.gz
  fsck result: failed (log: https://syzkaller.appspot.com/x/fsck.log?x=138a501c580000)
mounted in repro #2: https://storage.googleapis.com/syzbot-assets/e4d71ffc49fe/mount_14.gz
  fsck result: failed (log: https://syzkaller.appspot.com/x/fsck.log?x=178a501c580000)
mounted in repro #3: https://storage.googleapis.com/syzbot-assets/35380d3f8199/mount_18.gz
  fsck result: OK (log: https://syzkaller.appspot.com/x/fsck.log?x=1650cd56580000)

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+015483fc71d1413f40ee@syzkaller.appspotmail.com

loop0: detected capacity change from 0 to 32768
------------[ cut here ]------------
UBSAN: array-index-out-of-bounds in fs/jfs/jfs_imap.c:2105:2
index 8592359 is out of range for type 'struct iagctl[128]'
CPU: 0 UID: 0 PID: 6143 Comm: syz.0.211 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 ubsan_epilogue+0xa/0x30 lib/ubsan.c:233
 __ubsan_handle_out_of_bounds+0xe8/0xf0 lib/ubsan.c:455
 diAllocBit+0xb88/0xd30 fs/jfs/jfs_imap.c:2105
 diAllocIno fs/jfs/jfs_imap.c:1844 [inline]
 diAllocAG+0x13f7/0x1de0 fs/jfs/jfs_imap.c:1676
 diAlloc+0x1e2/0x16b0 fs/jfs/jfs_imap.c:1590
 ialloc+0x8c/0x8e0 fs/jfs/jfs_inode.c:56
 jfs_create+0x1d8/0xae0 fs/jfs/namei.c:93
 lookup_open fs/namei.c:4508 [inline]
 open_last_lookups fs/namei.c:4608 [inline]
 path_openat+0x133a/0x3830 fs/namei.c:4856
 do_file_open+0x23e/0x4a0 fs/namei.c:4888
 do_sys_openat2+0x115/0x200 fs/open.c:1395
 do_sys_open fs/open.c:1401 [inline]
 __do_sys_open fs/open.c:1409 [inline]
 __se_sys_open fs/open.c:1405 [inline]
 __x64_sys_open+0x11e/0x150 fs/open.c:1405
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fc75779ce59
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fc758713028 EFLAGS: 00000246 ORIG_RAX: 0000000000000002
RAX: ffffffffffffffda RBX: 00007fc757a15fa0 RCX: 00007fc75779ce59
RDX: 0000000000000292 RSI: 0000000000064842 RDI: 0000200000000080
RBP: 00007fc757832e6f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fc757a16038 R14: 00007fc757a15fa0 R15: 00007ffc5cf2ad48
 </TASK>
---[ end trace ]---


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