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

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 50cbba13faa2 Linux 6.1.159
git tree: linux-6.1.y
console output: https://syzkaller.appspot.com/x/log.txt?x=132a8f92580000
kernel config: https://syzkaller.appspot.com/x/.config?x=31ea1cecaf34f0db
dashboard link: https://syzkaller.appspot.com/bug?extid=09ac93a00a6b946e9505
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
userspace arch: arm64

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/7ad0bd66715a/disk-50cbba13.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/3284d626258e/vmlinux-50cbba13.xz
kernel image: https://storage.googleapis.com/syzbot-assets/a1f92ca7bbfc/Image-50cbba13.gz.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+09ac93...@syzkaller.appspotmail.com

REISERFS (device loop4): Using tea hash to sort names
REISERFS (device loop4): Created .reiserfs_priv - reserved for xattr storage.
loop4: detected capacity change from 8192 to 2
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: 4658 Comm: syz.4.57 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/03/2025
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+0x424/0x750 fs/reiserfs/fix_node.c:901
lr : sb_getblk include/linux/buffer_head.h:356 [inline]
lr : get_empty_nodes+0x41c/0x750 fs/reiserfs/fix_node.c:890
sp : ffff800021486820
x29: ffff800021486960 x28: dfff800000000000 x27: ffff0000c049ee00
x26: 0000000000000000 x25: 0000000000000000 x24: ffff800021486910
x23: ffff0000cd754018 x22: ffff0000cd754160 x21: 1fffe00019aea803
x20: 1ffff00004290d97 x19: ffff800021486910 x18: 0000000000000000
x17: ffff800018184000 x16: ffff8000082e9244 x15: ffff80000898e28c
x14: ffff80000898e168 x13: 1ffff00002a0a0b1 x12: 0000000000080000
x11: 0000000000005336 x10: ffff8000252da000 x9 : ffff800008a80900
x8 : 0000000000000000 x7 : 0000000000000000 x6 : 0000000000000000
x5 : 0000000000000000 x4 : 0000000000000008 x3 : ffff800008a806c8
x2 : 0000000000000001 x1 : 0000000000000003 x0 : 0000000000000000
Call trace:
sb_getblk include/linux/buffer_head.h:356 [inline]
get_empty_nodes+0x424/0x750 fs/reiserfs/fix_node.c:890
fix_nodes+0x1dd8/0x6b4c fs/reiserfs/fix_node.c:2662
reiserfs_paste_into_item+0x4e8/0x6d0 fs/reiserfs/stree.c:2130
reiserfs_get_block+0x1444/0x3524 fs/reiserfs/inode.c:1069
__block_write_begin_int+0x34c/0x13b8 fs/buffer.c:1991
__block_write_begin+0x7c/0xa0 fs/buffer.c:2041
reiserfs_write_begin+0x328/0x71c fs/reiserfs/inode.c:2775
generic_cont_expand_simple+0x12c/0x1fc fs/buffer.c:2347
reiserfs_setattr+0x564/0xf7c fs/reiserfs/inode.c:3305
notify_change+0xb0c/0xdcc fs/attr.c:499
do_truncate+0x178/0x1f0 fs/open.c:65
vfs_truncate+0x23c/0x2b0 fs/open.c:111
do_sys_truncate+0xe8/0x1b0 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+0x98/0x2bc arch/arm64/kernel/syscall.c:52
el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:140
do_el0_svc+0x58/0x13c arch/arm64/kernel/syscall.c:204
el0_svc+0x58/0x138 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 97f7ad6d d343fc08 aa0003fa (387c6908)
---[ end trace 0000000000000000 ]---
----------------
Code disassembly (best guess):
0: 52800103 mov w3, #0x8 // #8
4: 97f7ad6d bl 0xffffffffffdeb5b8
8: d343fc08 lsr x8, x0, #3
c: aa0003fa mov x26, x0
* 10: 387c6908 ldrb w8, [x8, x28] <-- trapping instruction


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