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BUG: KASAN: null-ptr-deref in instrument_atomic_read include/linux/instrumented.h:72 [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:123 [inline]
BUG: KASAN: null-ptr-deref in fix_nodes+0x435/0x82d0 fs/reiserfs/fix_node.c:2578
Read of size 8 at addr 0000000000000000 by task syz.1.71/4698

CPU: 0 PID: 4698 Comm: syz.1.71 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x168/0x22e lib/dump_stack.c:106
 kasan_report+0x10b/0x140 mm/kasan/report.c:524
 check_region_inline mm/kasan/generic.c:-1 [inline]
 kasan_check_range+0x27b/0x290 mm/kasan/generic.c:189
 instrument_atomic_read include/linux/instrumented.h:72 [inline]
 _test_bit include/asm-generic/bitops/instrumented-non-atomic.h:141 [inline]
 buffer_locked include/linux/buffer_head.h:123 [inline]
 fix_nodes+0x435/0x82d0 fs/reiserfs/fix_node.c:2578
 reiserfs_cut_from_item+0x2e8/0x1ef0 fs/reiserfs/stree.c:1742
 reiserfs_do_truncate+0xa90/0x13e0 fs/reiserfs/stree.c:1973
 reiserfs_truncate_file+0x376/0x7c0 fs/reiserfs/inode.c:2310
 reiserfs_setattr+0xcae/0x1240 fs/reiserfs/inode.c:3395
 notify_change+0xc74/0xf40 fs/attr.c:499
 do_truncate+0x197/0x220 fs/open.c:65
 handle_truncate fs/namei.c:3293 [inline]
 do_open fs/namei.c:3638 [inline]
 path_openat+0x27f2/0x2e70 fs/namei.c:3791
 do_filp_open+0x1c1/0x3c0 fs/namei.c:3818
 do_sys_openat2+0x142/0x490 fs/open.c:1320
 do_sys_open fs/open.c:1336 [inline]
 __do_sys_openat fs/open.c:1352 [inline]
 __se_sys_openat fs/open.c:1347 [inline]
 __x64_sys_openat+0x135/0x160 fs/open.c:1347
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f2ebcd8f749
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f2ebdbdc038 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007f2ebcfe5fa0 RCX: 00007f2ebcd8f749
RDX: 0000000000103a42 RSI: 0000200000000380 RDI: ffffffffffffff9c
RBP: 00007f2ebce13f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f2ebcfe6038 R14: 00007f2ebcfe5fa0 R15: 00007ffdb8933b98
 </TASK>
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