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

[syzbot <syzbot+b974bd41515f770c608b@syzkaller.appspotmail.com>]

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
UBSAN: array-index-out-of-bounds in add_missing_indices

 ... Log Wrap ... Log Wrap ... Log Wrap ...
================================================================================
UBSAN: array-index-out-of-bounds in fs/jfs/jfs_dtree.c:2946:28
index -128 is out of range for type 'struct dtslot[128]'
CPU: 1 PID: 5111 Comm: syz.0.16 Not tainted 5.15.180-syzkaller-07499-gf7347f400572-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
Call trace:
 dump_backtrace+0x0/0x530 arch/arm64/kernel/stacktrace.c:152
 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:216
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x108/0x170 lib/dump_stack.c:106
 dump_stack+0x1c/0x58 lib/dump_stack.c:113
 ubsan_epilogue lib/ubsan.c:151 [inline]
 __ubsan_handle_out_of_bounds+0x108/0x15c lib/ubsan.c:282
 add_missing_indices+0x6d0/0xaac fs/jfs/jfs_dtree.c:2946
 jfs_readdir+0x1974/0x31dc fs/jfs/jfs_dtree.c:3316
 iterate_dir+0x1f4/0x4ec fs/readdir.c:-1
 __do_sys_getdents64 fs/readdir.c:369 [inline]
 __se_sys_getdents64 fs/readdir.c:354 [inline]
 __arm64_sys_getdents64+0x1c4/0x4c4 fs/readdir.c:354
 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
 invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:52
 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
 do_el0_svc+0x58/0x14c arch/arm64/kernel/syscall.c:181
 el0_svc+0x7c/0x1f0 arch/arm64/kernel/entry-common.c:608
 el0t_64_sync_handler+0x84/0xe4 arch/arm64/kernel/entry-common.c:626
 el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584
================================================================================
==================================================================
BUG: KASAN: slab-out-of-bounds in diWrite+0xb48/0x1604 fs/jfs/jfs_imap.c:753
Read of size 32 at addr ffffff80e1ab4130 by task syz.0.16/5111

CPU: 1 PID: 5111 Comm: syz.0.16 Not tainted 5.15.180-syzkaller-07499-gf7347f400572-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
Call trace:
 dump_backtrace+0x0/0x530 arch/arm64/kernel/stacktrace.c:152
 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:216
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x108/0x170 lib/dump_stack.c:106
 print_address_description+0x7c/0x3f0 mm/kasan/report.c:248
 __kasan_report mm/kasan/report.c:434 [inline]
 kasan_report+0x174/0x1e4 mm/kasan/report.c:451
 check_region_inline mm/kasan/generic.c:-1 [inline]
 kasan_check_range+0x274/0x2b4 mm/kasan/generic.c:189
 memcpy+0x90/0xe8 mm/kasan/shadow.c:65
 diWrite+0xb48/0x1604 fs/jfs/jfs_imap.c:753
 txCommit+0x748/0x5548 fs/jfs/jfs_txnmgr.c:1255
 add_missing_indices+0x74c/0xaac fs/jfs/jfs_dtree.c:2960
 jfs_readdir+0x1974/0x31dc fs/jfs/jfs_dtree.c:3316
 iterate_dir+0x1f4/0x4ec fs/readdir.c:-1
 __do_sys_getdents64 fs/readdir.c:369 [inline]
 __se_sys_getdents64 fs/readdir.c:354 [inline]
 __arm64_sys_getdents64+0x1c4/0x4c4 fs/readdir.c:354
 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
 invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:52
 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
 do_el0_svc+0x58/0x14c arch/arm64/kernel/syscall.c:181
 el0_svc+0x7c/0x1f0 arch/arm64/kernel/entry-common.c:608
 el0t_64_sync_handler+0x84/0xe4 arch/arm64/kernel/entry-common.c:626
 el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584

Allocated by task 0:
(stack is not available)

The buggy address belongs to the object at ffffff80e1ab40c0
 which belongs to the cache jfs_ip of size 2240
The buggy address is located 112 bytes inside of
 2240-byte region [ffffff80e1ab40c0, ffffff80e1ab4980)
The buggy address belongs to the page:
page:000000008771d7e4 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x121ab0
head:000000008771d7e4 order:3 compound_mapcount:0 compound_pincount:0
memcg:ffffff80c76f5501
flags: 0x5ffc00000010200(slab|head|node=0|zone=2|lastcpupid=0x7ff)
raw: 05ffc00000010200 0000000000000000 dead000000000122 ffffff80c6707680
raw: 0000000000000000 00000000800d000d 00000001ffffffff ffffff80c76f5501
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffffff80e1ab4000: 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc
 ffffff80e1ab4080: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffffff80e1ab4100: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
                                     ^
 ffffff80e1ab4180: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffffff80e1ab4200: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================

 ... Log Wrap ... Log Wrap ... Log Wrap ...


 ... Log Wrap ... Log Wrap ... Log Wrap ...


 ... Log Wrap ... Log Wrap ... Log Wrap ...

ERROR: (device loop0): jfs_readdir: JFS:Dtree error: ino = 2, bn=0, index = 0

ERROR: (device loop0): remounting filesystem as read-only
JFS: Invalid stbl[1] = -128 for inode 2, block = 0


Tested on:

commit:         f7347f40 Linux 5.15.180
git tree:       git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git linux-5.15.y
console output: https://syzkaller.appspot.com/x/log.txt?x=132e08cc580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=e433a356d25f60cb
dashboard link: https://syzkaller.appspot.com/bug?extid=b974bd41515f770c608b
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
userspace arch: arm64
patch:          https://syzkaller.appspot.com/x/patch.diff?x=12762470580000