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WARNING in inc_nlink (2)

Status: fixed on 2022/03/08 16:11
Subsystems: fs
[Documentation on labels]
Reported-by: syzbot+1c8034b9f0e640f9ba45@syzkaller.appspotmail.com
Fix commit: 97f044f690ba fuse: don't increment nlink in link()
First crash: 1688d, last: 1349d
Cause bisection: the issue happens on the oldest tested release (bisect log)
Crash: WARNING in inc_nlink (log)
Repro: C syz .config
  
Fix bisection: fixed by (bisect log) :
commit 97f044f690bac2b094bfb7fb2d177ef946c85880
Author: Miklos Szeredi <mszeredi@redhat.com>
Date: Fri Oct 22 15:03:02 2021 +0000

  fuse: don't increment nlink in link()

  
▶ ▼ Discussions (1)
Title Replies (including bot) Last reply
[syzbot] WARNING in inc_nlink (2) 2 (4) 2021/11/25 11:23
▶ ▼ Similar bugs (10)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.6 WARNING in inc_nlink origin:lts-only -1 C 22 8d06h 148d 0/2 upstream: reported C repro on 2025/06/21 08:35
linux-4.19 WARNING in inc_nlink (2) -1 C error 102 1085d 1841d 0/1 upstream: reported C repro on 2020/11/01 15:25
linux-5.15 WARNING in inc_nlink origin:lts-only -1 C done 761 1d04h 972d 0/3 upstream: reported C repro on 2023/03/20 05:26
upstream WARNING in inc_nlink (3) fs -1 C error error 6895 4d00h 1340d 0/29 upstream: reported C repro on 2022/03/17 16:37
linux-6.1 WARNING in inc_nlink -1 81 929d 951d 0/3 auto-obsoleted due to no activity on 2023/07/31 15:23
linux-4.19 WARNING in inc_nlink -1 C done 8 1915d 2064d 1/1 fixed on 2020/09/18 07:23
linux-4.14 WARNING in inc_nlink -1 C done 21 1923d 2065d 1/1 fixed on 2020/09/11 09:49
linux-4.14 WARNING in inc_nlink (2) -1 C 47 1001d 1836d 0/1 upstream: reported C repro on 2020/11/06 09:55
upstream WARNING in inc_nlink -1 C done 26 1953d 2056d 15/29 fixed on 2020/09/16 22:51
linux-6.1 WARNING in inc_nlink (2) origin:upstream missing-backport -1 C done 437 2h58m 689d 0/3 upstream: reported C repro on 2023/12/28 21:17
▶ ▼ Fix bisection attempts (4)
Created Duration User Patch Repo Result
2021/11/17 02:04 3h27m bisect fix upstream OK (1) job log
2021/09/15 01:53 21m bisect fix upstream OK (0) job log log
2021/08/15 19:17 20m bisect fix upstream OK (0) job log log
2021/07/15 08:37 21m bisect fix upstream OK (0) job log log

Sample crash report:
------------[ cut here ]------------
WARNING: CPU: 1 PID: 6562 at fs/inode.c:365 inc_nlink+0x144/0x160 fs/inode.c:365
Modules linked in:
CPU: 1 PID: 6562 Comm: syz-executor080 Not tainted 5.15.0-rc4-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:inc_nlink+0x144/0x160 fs/inode.c:365
Code: ff 4c 89 e7 e8 ad c4 ed ff e9 42 ff ff ff 4c 89 e7 e8 30 c4 ed ff e9 fc fe ff ff 4c 89 e7 e8 23 c4 ed ff eb d4 e8 cc 6e a6 ff <0f> 0b e9 6e ff ff ff e8 20 c4 ed ff e9 44 ff ff ff e8 16 c4 ed ff
RSP: 0018:ffffc90002bafc48 EFLAGS: 00010293
RAX: 0000000000000000 RBX: ffff88806ce98000 RCX: 0000000000000000
RDX: ffff888021080000 RSI: ffffffff81cf8fb4 RDI: 0000000000000003
RBP: 0000000000000000 R08: 0000000000000000 R09: ffff88802235d2bf
R10: ffffffff81cf8f20 R11: 0000000000000000 R12: ffff88806ce98048
R13: ffff88806ce985e0 R14: 0000000000000000 R15: ffffc90002bafcd0
FS:  00007fa1e19a9700(0000) GS:ffff8880b9d00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fa1e1a4e0c8 CR3: 0000000072d15000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 fuse_link+0x35b/0x5b0 fs/fuse/dir.c:931
 vfs_link+0x544/0x9c0 fs/namei.c:4378
 do_linkat+0x444/0x5e0 fs/namei.c:4449
 __do_sys_link fs/namei.c:4483 [inline]
 __se_sys_link fs/namei.c:4481 [inline]
 __x64_sys_link+0x7d/0xa0 fs/namei.c:4481
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x7fa1e19f7b79
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 81 14 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:00007fa1e19a92f8 EFLAGS: 00000246 ORIG_RAX: 0000000000000056
RAX: ffffffffffffffda RBX: 00007fa1e1a884c0 RCX: 00007fa1e19f7b79
RDX: 00007fa1e19f7b79 RSI: 0000000020000080 RDI: 0000000020000040
RBP: 00007fa1e1a560e4 R08: 0000000000003065 R09: 0000000000000000
R10: 0000000000003065 R11: 0000000000000246 R12: 00007fa1e1a500d0
R13: 00007fa1e1a520d8 R14: 00007fa1e1a540e0 R15: 00007fa1e1a884c8

Crashes (21):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2021/10/08 10:39 upstream 1da38549dd64 efe0f24d .config console log report syz C ci-upstream-kasan-gce WARNING in inc_nlink
2021/05/12 04:57 upstream 88b06399c9c7 b3c3bb8e .config console log report syz C ci-upstream-kasan-gce-selinux-root WARNING in inc_nlink
2021/05/01 18:42 upstream d2b6f8a17919 77e2b668 .config console log report syz C ci-upstream-kasan-gce-selinux-root WARNING in inc_nlink
2021/04/09 12:28 upstream 4fa56ad0d12e 6a81331a .config console log report syz C ci-upstream-kasan-gce-smack-root WARNING in inc_nlink
2021/04/04 03:10 upstream 57fbdb15ec42 6a81331a .config console log report syz C ci-upstream-kasan-gce-smack-root WARNING in inc_nlink
2021/04/03 21:47 upstream 57fbdb15ec42 6a81331a .config console log report syz C ci-upstream-kasan-gce-root WARNING in inc_nlink
2021/05/13 08:17 linux-next ec85c95b0c90 ed7d41c5 .config console log report syz C ci-upstream-linux-next-kasan-gce-root WARNING in inc_nlink
2021/05/08 08:23 linux-next 869a85b925fc bc5434be .config console log report syz C ci-upstream-linux-next-kasan-gce-root WARNING in inc_nlink
2022/03/08 06:30 upstream ea4424be1688 7bdd8b2c .config console log report info ci-upstream-kasan-gce-root WARNING in inc_nlink
2022/02/09 00:18 upstream e6251ab4551f 0b33604d .config console log report info ci-upstream-kasan-gce-root WARNING in inc_nlink
2022/02/08 06:33 upstream 555f3d7be91a a7dab638 .config console log report info ci-upstream-kasan-gce-root WARNING in inc_nlink
2021/10/18 02:04 upstream d999ade1cc86 0c5d9412 .config console log report info ci-upstream-kasan-gce-root WARNING in inc_nlink
2021/06/15 07:59 upstream 009c9aa5be65 1ba81399 .config console log report info ci-upstream-kasan-gce-root WARNING in inc_nlink
2021/05/16 13:46 upstream 63d1cb53e26a f54a5c09 .config console log report info ci-upstream-kasan-gce-root WARNING in inc_nlink
2021/04/13 02:36 upstream d434405aaab7 bfeda1b1 .config console log report info ci-upstream-kasan-gce-root WARNING in inc_nlink
2022/03/08 07:00 upstream ea4424be1688 7bdd8b2c .config console log report info ci-qemu-upstream-386 WARNING in inc_nlink
2022/03/08 06:35 linux-next 91265a6da44d 7bdd8b2c .config console log report info ci-upstream-linux-next-kasan-gce-root WARNING in inc_nlink
2022/02/19 19:37 linux-next ef6b35306dd8 3cd800e4 .config console log report info ci-upstream-linux-next-kasan-gce-root WARNING in inc_nlink
2022/02/11 22:11 linux-next ef6b35306dd8 8b9ca619 .config console log report info ci-upstream-linux-next-kasan-gce-root WARNING in inc_nlink
2021/10/18 01:55 linux-next 7c832d2f9b95 0c5d9412 .config console log report info ci-upstream-linux-next-kasan-gce-root WARNING in inc_nlink
2021/06/01 17:28 linux-next a1f92694393a 032639db .config console log report info ci-upstream-linux-next-kasan-gce-root WARNING in inc_nlink
* Struck through repros no longer work on HEAD.