[v6.1] BUG: unable to handle kernel paging request in get_empty_nodes (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 4931e0e1673d Linux 6.1.170
git tree: linux-6.1.y
console output: https://syzkaller.appspot.com/x/log.txt?x=16077082580000
kernel config: https://syzkaller.appspot.com/x/.config?x=b1adc0bfde2d8a4a
dashboard link: https://syzkaller.appspot.com/bug?extid=7b50dcfb9ae636c8b91e
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
userspace arch: arm64

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/1d2e800805ca/disk-4931e0e1.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/86557170127a/vmlinux-4931e0e1.xz
kernel image: https://storage.googleapis.com/syzbot-assets/f9b3a6753f2d/Image-4931e0e1.gz.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+7b50dc...@syzkaller.appspotmail.com

Unable to handle kernel paging request at virtual address dfff800000000000
KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
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
[dfff800000000000] address between user and kernel address ranges
Internal error: Oops: 0000000096000006 [#1] PREEMPT SMP
Modules linked in:
CPU: 0 PID: 4434 Comm: syz.1.2 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
pstate: 82400005 (Nzcv daif +PAN -UAO +TCO -DIT -SSBS BTYPE=--)
pc : generic_test_bit include/asm-generic/bitops/generic-non-atomic.h:128 [inline]
pc : set_buffer_journal_new fs/reiserfs/reiserfs.h:2834 [inline]
pc : get_empty_nodes+0x450/0x77c fs/reiserfs/fix_node.c:901
lr : sb_getblk include/linux/buffer_head.h:356 [inline]
lr : get_empty_nodes+0x448/0x77c fs/reiserfs/fix_node.c:890
sp : ffff800020f66820
x29: ffff800020f66960 x28: dfff800000000000 x27: ffff0000c049cd00
x26: 0000000000000000 x25: 0000000000000000 x24: ffff800020f66910
x23: ffff0000f67de018 x22: ffff0000f67de160 x21: 1fffe0001ecfbc03
x20: 1ffff000041ecd97 x19: ffff800020f66910 x18: ffff800011b9bf60
x17: 1fffe00033ea637e x16: ffff8000082d92bc x15: ffff80001521d000
x14: 0000000000000001 x13: 1fffff80007b4e26 x12: 0000000000080000
x11: 000000000000bb22 x10: ffff8000257ec000 x9 : ffff800008a916bc
x8 : 0000000000000000 x7 : 0000000000000000 x6 : 1fffe00033ea637f
x5 : ffff8000152c1c60 x4 : 0000000000000008 x3 : ffff800008a9148c
x2 : 0000000000000001 x1 : 0000000000000003 x0 : 0000000000000000
Call trace:
sb_getblk include/linux/buffer_head.h:356 [inline]
get_empty_nodes+0x450/0x77c fs/reiserfs/fix_node.c:890
ip_check_balance fs/reiserfs/fix_node.c:1381 [inline]
check_balance fs/reiserfs/fix_node.c:2083 [inline]
fix_nodes+0xd90/0x6b70 fs/reiserfs/fix_node.c:2635
reiserfs_paste_into_item+0x504/0x6e0 fs/reiserfs/stree.c:2130
reiserfs_get_block+0x14a0/0x36e8 fs/reiserfs/inode.c:1069
__block_write_begin_int+0x350/0x1388 fs/buffer.c:1991
__block_write_begin+0x7c/0xa0 fs/buffer.c:2041
reiserfs_write_begin+0x328/0x714 fs/reiserfs/inode.c:2775
generic_cont_expand_simple+0x130/0x208 fs/buffer.c:2347
reiserfs_setattr+0x51c/0xfec fs/reiserfs/inode.c:3305
notify_change+0xb0c/0xdcc fs/attr.c:499
do_truncate+0x188/0x20c fs/open.c:65
vfs_truncate+0x23c/0x2b0 fs/open.c:111
do_sys_truncate+0xec/0x1b4 fs/open.c:134
__do_sys_truncate fs/open.c:146 [inline]
__se_sys_truncate fs/open.c:144 [inline]
__arm64_sys_truncate+0x5c/0x70 fs/open.c:144
__invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
invoke_syscall+0x98/0x2b4 arch/arm64/kernel/syscall.c:52
el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:140
do_el0_svc+0x58/0x130 arch/arm64/kernel/syscall.c:204
el0_svc+0x58/0x128 arch/arm64/kernel/entry-common.c:637
el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585
Code: 52800103 97f79ca7 d343fc08 aa0003fa (387c6908)
---[ end trace 0000000000000000 ]---
----------------
Code disassembly (best guess):
0: 52800103 mov w3, #0x8 // #8
4: 97f79ca7 bl 0xffffffffffde72a0
8: d343fc08 lsr x8, x0, #3
c: aa0003fa mov x26, x0
* 10: 387c6908 ldrb w8, [x8, x28] <-- trapping instruction


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[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit: 4931e0e1673d Linux 6.1.170
git tree: linux-6.1.y

console output: https://syzkaller.appspot.com/x/log.txt?x=14275696580000

kernel config: https://syzkaller.appspot.com/x/.config?x=b1adc0bfde2d8a4a
dashboard link: https://syzkaller.appspot.com/bug?extid=7b50dcfb9ae636c8b91e
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
userspace arch: arm64

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=12fff506580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=11cf7ece580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/1d2e800805ca/disk-4931e0e1.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/86557170127a/vmlinux-4931e0e1.xz
kernel image: https://storage.googleapis.com/syzbot-assets/f9b3a6753f2d/Image-4931e0e1.gz.xz

mounted in repro: https://storage.googleapis.com/syzbot-assets/57f872b4774a/mount_0.gz
fsck result: failed (log: https://syzkaller.appspot.com/x/fsck.log?x=140ada36580000)

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+7b50dc...@syzkaller.appspotmail.com

Unable to handle kernel paging request at virtual address dfff800000000000
KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
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
[dfff800000000000] address between user and kernel address ranges
Internal error: Oops: 0000000096000006 [#1] PREEMPT SMP
Modules linked in:

CPU: 1 PID: 4564 Comm: syz.0.17 Not tainted syzkaller #0

Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
pstate: 82400005 (Nzcv daif +PAN -UAO +TCO -DIT -SSBS BTYPE=--)
pc : generic_test_bit include/asm-generic/bitops/generic-non-atomic.h:128 [inline]
pc : set_buffer_journal_new fs/reiserfs/reiserfs.h:2834 [inline]
pc : get_empty_nodes+0x450/0x77c fs/reiserfs/fix_node.c:901
lr : sb_getblk include/linux/buffer_head.h:356 [inline]
lr : get_empty_nodes+0x448/0x77c fs/reiserfs/fix_node.c:890

sp : ffff800021aa6820
x29: ffff800021aa6960 x28: dfff800000000000 x27: ffff0000c049c200
x26: 0000000000000000 x25: 0000000000000000 x24: ffff800021aa6910
x23: ffff0000c772e018 x22: ffff0000c772e160 x21: 1fffe00018ee5c03
x20: 1ffff00004354d97 x19: ffff800021aa6910 x18: ffff800011b9bf60
x17: ffff80001835b000 x16: ffff8000082d92bc x15: ffff800017e3c000
x14: 0000000000000001 x13: 1fffff80006d2d86 x12: 0000000000ff0100
x11: ff00800008a916bc x10: 0000000000000000 x9 : ffff800008a916bc
x8 : 0000000000000000 x7 : 0000000000000000 x6 : 0000000000000000
x5 : 0000000000000080 x4 : 0000000000000000 x3 : ffff800008a9148c

If you want syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
If you attach or paste a git patch, syzbot will apply it before testing.