Re: [syzbot] [jfs?] KASAN: null-ptr-deref Read in txBegin

[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit:    14f8db1c0f9a Merge branch 'for-next/core' into for-kernelci
git tree:       git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci
console output: https://syzkaller.appspot.com/x/log.txt?x=12f5764e280000
kernel config:  https://syzkaller.appspot.com/x/.config?x=a837a8ba7e88bb45
dashboard link: https://syzkaller.appspot.com/bug?extid=f1faa20eec55e0c8644c
compiler:       Debian clang version 15.0.7, GNU ld (GNU Binutils for Debian) 2.35.2
userspace arch: arm64
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=15b9e24e280000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=105d3e46280000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/ad6ce516eed3/disk-14f8db1c.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/1f38c2cc7667/vmlinux-14f8db1c.xz
kernel image: https://storage.googleapis.com/syzbot-assets/d795115eee39/Image-14f8db1c.gz.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/014681b264cc/mount_0.gz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+f1faa20eec55e0c8644c@xxxxxxxxxxxxxxxxxxxxxxxxx

WARNING: The mand mount option has been deprecated and
         and is ignored by this kernel. Remove the mand
         option from the mount to silence this warning.
=======================================================
Unable to handle kernel paging request at virtual address dfff800000000008
KASAN: null-ptr-deref in range [0x0000000000000040-0x0000000000000047]
Mem abort info:
  ESR = 0x0000000096000006
  EC = 0x25: DABT (current EL), IL = 32 bits
  SET = 0, FnV = 0
  EA = 0, S1PTW = 0
  FSC = 0x06: level 2 translation fault
Data abort info:
  ISV = 0, ISS = 0x00000006
  CM = 0, WnR = 0
[dfff800000000008] address between user and kernel address ranges
Internal error: Oops: 0000000096000006 [#1] PREEMPT SMP
Modules linked in:
CPU: 0 PID: 5926 Comm: syz-executor228 Not tainted 6.3.0-rc7-syzkaller-g14f8db1c0f9a #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/14/2023
pstate: 80400005 (Nzcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : generic_test_bit include/asm-generic/bitops/generic-non-atomic.h:128 [inline]
pc : txBegin+0x138/0x5e0 fs/jfs/jfs_txnmgr.c:366
lr : txBegin+0x104/0x5e0 fs/jfs/jfs_txnmgr.c:357
sp : ffff80001eb37660
x29: ffff80001eb37680 x28: dfff800000000000 x27: dfff800000000000
x26: ffff800016308bc8 x25: 0000000000000040 x24: 0000000000000000
x23: ffff800016306520 x22: ffff0000d6a57c30 x21: 0000000000000150
x20: 0000000000000008 x19: 0000000000000000 x18: ffff80001eb37360
x17: ffff800008ad82e4 x16: ffff80000831ae40 x15: 000000000000bb8c
x14: 000000003eb35159 x13: dfff800000000000 x12: ffff700003d66eb4
x11: 0000000000000001 x10: 0000000000000000 x9 : 0000000000000000
x8 : 1ffff00002c5f670 x7 : 0000000000000000 x6 : 0000000000000000
x5 : ffff800019238f80 x4 : 0000000000000008 x3 : ffff80000831af70
x2 : 0000000000000001 x1 : 0000000000000000 x0 : 0000000000000000
Call trace:
 txBegin+0x138/0x5e0 fs/jfs/jfs_txnmgr.c:362
 __jfs_xattr_set+0xc8/0x190 fs/jfs/xattr.c:915
 jfs_xattr_set+0x58/0x70 fs/jfs/xattr.c:941
 __vfs_setxattr+0x3d8/0x400 fs/xattr.c:203
 __vfs_setxattr_noperm+0x110/0x528 fs/xattr.c:237
 __vfs_setxattr_locked+0x1ec/0x218 fs/xattr.c:298
 vfs_setxattr+0x1a8/0x344 fs/xattr.c:324
 do_setxattr fs/xattr.c:609 [inline]
 setxattr+0x208/0x29c fs/xattr.c:632
 path_setxattr+0x17c/0x258 fs/xattr.c:651
 __do_sys_setxattr fs/xattr.c:667 [inline]
 __se_sys_setxattr fs/xattr.c:663 [inline]
 __arm64_sys_setxattr+0xbc/0xd8 fs/xattr.c:663
 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
 invoke_syscall+0x98/0x2c0 arch/arm64/kernel/syscall.c:52
 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
 do_el0_svc+0x64/0x198 arch/arm64/kernel/syscall.c:193
 el0_svc+0x4c/0x15c arch/arm64/kernel/entry-common.c:637
 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
 el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:591
Code: 9400012e aa1703e0 95954bf6 350002f8 (387c6a88) 
---[ end trace 0000000000000000 ]---
----------------
Code disassembly (best guess):
   0:	9400012e 	bl	0x4b8
   4:	aa1703e0 	mov	x0, x23
   8:	95954bf6 	bl	0x6552fe0
   c:	350002f8 	cbnz	w24, 0x68
* 10:	387c6a88 	ldrb	w8, [x20, x28] <-- trapping instruction


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