linux-kernel - Re: [syzbot] [reiserfs?] KASAN: null-ptr-deref Read in fix

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Message-ID: <00000000000063df4305fe31b6c7@google.com>
Date:   Thu, 15 Jun 2023 14:25:50 -0700
From:   syzbot <syzbot+5184326923f180b9d11a@...kaller.appspotmail.com>
To:     linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
        reiserfs-devel@...r.kernel.org, syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] [reiserfs?] KASAN: null-ptr-deref Read in fix_nodes

syzbot has found a reproducer for the following issue on:

HEAD commit:    b6dad5178cea Merge tag 'nios2_fix_v6.4' of git://git.kerne..
git tree:       upstream
console+strace: https://syzkaller.appspot.com/x/log.txt?x=1495dce3280000
kernel config:  https://syzkaller.appspot.com/x/.config?x=ac246111fb601aec
dashboard link: https://syzkaller.appspot.com/bug?extid=5184326923f180b9d11a
compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=10bbc887280000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=15c9558b280000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/fb7aeb21864c/disk-b6dad517.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/3004476364b7/vmlinux-b6dad517.xz
kernel image: https://storage.googleapis.com/syzbot-assets/a143be294854/bzImage-b6dad517.xz
mounted in repro #1: https://storage.googleapis.com/syzbot-assets/92adf3c12845/mount_1.gz
mounted in repro #2: https://storage.googleapis.com/syzbot-assets/3861119d1700/mount_8.gz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+5184326923f180b9d11a@...kaller.appspotmail.com

REISERFS error (device loop2): vs-5150 search_by_key: invalid format found in block 540. Fsck?
==================================================================
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:126 [inline]
BUG: KASAN: null-ptr-deref in fix_nodes+0x464/0x8660 fs/reiserfs/fix_node.c:2578
Read of size 8 at addr 0000000000000000 by task syz-executor539/5535

CPU: 0 PID: 5535 Comm: syz-executor539 Not tainted 6.4.0-rc6-syzkaller-00037-gb6dad5178cea #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/27/2023
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xd9/0x150 lib/dump_stack.c:106
 print_report mm/kasan/report.c:465 [inline]
 kasan_report+0xec/0x130 mm/kasan/report.c:572
 check_region_inline mm/kasan/generic.c:181 [inline]
 kasan_check_range+0x141/0x190 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:126 [inline]
 fix_nodes+0x464/0x8660 fs/reiserfs/fix_node.c:2578
 reiserfs_cut_from_item+0x2bd/0x1b20 fs/reiserfs/stree.c:1740
 reiserfs_do_truncate+0x630/0x1080 fs/reiserfs/stree.c:1971
 reiserfs_truncate_file+0x1b5/0x1070 fs/reiserfs/inode.c:2308
 reiserfs_setattr+0xddf/0x1370 fs/reiserfs/inode.c:3393
 notify_change+0xb2c/0x1180 fs/attr.c:483
 do_truncate+0x143/0x200 fs/open.c:66
 handle_truncate fs/namei.c:3295 [inline]
 do_open fs/namei.c:3640 [inline]
 path_openat+0x2083/0x2750 fs/namei.c:3791
 do_filp_open+0x1ba/0x410 fs/namei.c:3818
 do_sys_openat2+0x16d/0x4c0 fs/open.c:1356
 do_sys_open fs/open.c:1372 [inline]
 __do_sys_open fs/open.c:1380 [inline]
 __se_sys_open fs/open.c:1376 [inline]
 __x64_sys_open+0x11d/0x1c0 fs/open.c:1376
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f7cb89c3be9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 71 15 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 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f7cb094e2f8 EFLAGS: 00000246 ORIG_RAX: 0000000000000002
RAX: ffffffffffffffda RBX: 00007f7cb8a497f0 RCX: 00007f7cb89c3be9
RDX: 0000000000000000 RSI: 000000000014937e RDI: 0000000020000180
RBP: 00007f7cb8a16410 R08: 0000000000000000 R09: 0000000000000000
R10: 00000000000010f7 R11: 0000000000000246 R12: 0030656c69662f2e
R13: 7366726573696572 R14: 6bd71a7077694d3f R15: 00007f7cb8a497f8
 </TASK>
==================================================================


---
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#syz test: git://repo/address.git branch-or-commit-hash
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