==================================================================
BUG: KASAN: null-ptr-deref in instrument_atomic_read include/linux/instrumented.h:68 [inline]
BUG: KASAN: null-ptr-deref in _test_bit include/asm-generic/bitops/instrumented-non-atomic.h:141 [inline]
BUG: KASAN: null-ptr-deref in buffer_locked include/linux/buffer_head.h:124 [inline]
BUG: KASAN: null-ptr-deref in fix_nodes+0x4b2/0x8ae0 fs/reiserfs/fix_node.c:2579
Read of size 8 at addr 0000000000000000 by task syz-executor.0/6639

CPU: 1 PID: 6639 Comm: syz-executor.0 Not tainted 6.7.0-rc4-syzkaller-00009-gbee0e7762ad2 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/10/2023
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xd9/0x1b0 lib/dump_stack.c:106
 kasan_report+0xda/0x110 mm/kasan/report.c:588
 check_region_inline mm/kasan/generic.c:181 [inline]
 kasan_check_range+0xef/0x190 mm/kasan/generic.c:187
 instrument_atomic_read include/linux/instrumented.h:68 [inline]
 _test_bit include/asm-generic/bitops/instrumented-non-atomic.h:141 [inline]
 buffer_locked include/linux/buffer_head.h:124 [inline]
 fix_nodes+0x4b2/0x8ae0 fs/reiserfs/fix_node.c:2579
 reiserfs_cut_from_item+0x26a/0x1a10 fs/reiserfs/stree.c:1740
 reiserfs_do_truncate+0x672/0x10b0 fs/reiserfs/stree.c:1971
 reiserfs_truncate_file+0x1bf/0x940 fs/reiserfs/inode.c:2302
 reiserfs_setattr+0x9c3/0x12a0 fs/reiserfs/inode.c:3388
 notify_change+0x742/0x11c0 fs/attr.c:499
 do_truncate+0x15c/0x220 fs/open.c:66
 handle_truncate fs/namei.c:3280 [inline]
 do_open fs/namei.c:3626 [inline]
 path_openat+0x25a0/0x2c50 fs/namei.c:3779
 do_filp_open+0x1de/0x430 fs/namei.c:3809
 do_sys_openat2+0x176/0x1e0 fs/open.c:1440
 do_sys_open fs/open.c:1455 [inline]
 __do_sys_open fs/open.c:1463 [inline]
 __se_sys_open fs/open.c:1459 [inline]
 __x64_sys_open+0x154/0x1e0 fs/open.c:1459
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x40/0x110 arch/x86/entry/common.c:82
 entry_SYSCALL_64_after_hwframe+0x63/0x6b
RIP: 0033:0x7f2c3667cb29
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 e1 20 00 00 90 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 b0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f2c3730a0c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000002
RAX: ffffffffffffffda RBX: 00007f2c3679c050 RCX: 00007f2c3667cb29
RDX: 0000000000000000 RSI: 000000000014937e RDI: 0000000020000180
RBP: 00007f2c366c847a R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 000000000000006e R14: 00007f2c3679c050 R15: 00007ffc2f29f6c8
 </TASK>
==================================================================