From: Jeff Layton <jlayton@xxxxxxxxxx> Date: Thu, 06 Feb 2025 06:53:08 -0500 > On Thu, 2025-02-06 at 00:38 -0800, syzbot wrote: > > Hello, > > > > syzbot found the following issue on: > > > > HEAD commit: 92514ef226f5 Merge tag 'for-6.14-rc1-tag' of git://git.ker.. > > git tree: upstream > > console output: https://syzkaller.appspot.com/x/log.txt?x=151e9318580000 > > kernel config: https://syzkaller.appspot.com/x/.config?x=c48f582603dcb16c > > dashboard link: https://syzkaller.appspot.com/bug?extid=e34ad04f27991521104c > > compiler: gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40 > > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=131e9318580000 > > > > Downloadable assets: > > disk image: https://storage.googleapis.com/syzbot-assets/b3df3b128344/disk-92514ef2.raw.xz > > vmlinux: https://storage.googleapis.com/syzbot-assets/30f6f3763191/vmlinux-92514ef2.xz > > kernel image: https://storage.googleapis.com/syzbot-assets/caeb03ac3f9c/bzImage-92514ef2.xz > > > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > > Reported-by: syzbot+e34ad04f27991521104c@xxxxxxxxxxxxxxxxxxxxxxxxx > > > > name 'nfsd' > > WARNING: CPU: 1 PID: 6518 at fs/proc/generic.c:713 remove_proc_entry+0x268/0x470 fs/proc/generic.c:713 > > Modules linked in: > > CPU: 1 UID: 0 PID: 6518 Comm: kworker/u8:8 Not tainted 6.14.0-rc1-syzkaller-00034-g92514ef226f5 #0 > > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 12/27/2024 > > Workqueue: netns cleanup_net > > RIP: 0010:remove_proc_entry+0x268/0x470 fs/proc/generic.c:713 > > Code: 08 eb a2 e8 1a 9c 62 ff 48 c7 c7 20 7e 41 8e e8 4e c4 f2 08 e8 09 9c 62 ff 90 48 c7 c7 c0 db 81 8b 4c 89 e6 e8 29 76 23 ff 90 <0f> 0b 90 90 e9 72 ff ff ff e8 ea 9b 62 ff 49 8d be 98 00 00 00 48 > > RSP: 0018:ffffc9000bec7a80 EFLAGS: 00010286 > > RAX: 0000000000000000 RBX: 1ffff920017d8f52 RCX: ffffffff8179c889 > > RDX: ffff888031a35a00 RSI: ffffffff8179c896 RDI: 0000000000000001 > > RBP: 0000000000000000 R08: 0000000000000001 R09: 0000000000000000 > > R10: 0000000000000001 R11: 00000000000ca440 R12: ffffffff8b8f7460 > > R13: dffffc0000000000 R14: ffff88807e22da00 R15: fffffbfff1cb7dc4 > > FS: 0000000000000000(0000) GS:ffff8880b8700000(0000) knlGS:0000000000000000 > > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > > CR2: 0000000000000000 CR3: 00000000237ba000 CR4: 00000000003526f0 > > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > > Call Trace: > > <TASK> > > nfsd_net_exit+0x27/0x50 fs/nfsd/nfsctl.c:2259 > > ops_exit_list+0xb0/0x180 net/core/net_namespace.c:172 > > cleanup_net+0x5c6/0xbf0 net/core/net_namespace.c:652 > > process_one_work+0x958/0x1b30 kernel/workqueue.c:3236 > > process_scheduled_works kernel/workqueue.c:3317 [inline] > > worker_thread+0x6c8/0xf00 kernel/workqueue.c:3398 > > kthread+0x3af/0x750 kernel/kthread.c:464 > > ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:148 > > ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244 > > </TASK> > > > > > > --- > > This report is generated by a bot. It may contain errors. > > See https://goo.gl/tpsmEJ for more information about syzbot. > > syzbot engineers can be reached at syzkaller@xxxxxxxxxxxxxxxx. > > > > syzbot will keep track of this issue. See: > > https://goo.gl/tpsmEJ#status for how to communicate with syzbot. > > > > If the report is already addressed, let syzbot know by replying with: > > #syz fix: exact-commit-title > > > > If you want syzbot to run the reproducer, reply with: > > #syz test: git://repo/address.git branch-or-commit-hash > > If you attach or paste a git patch, syzbot will apply it before testing. > > > > If you want to overwrite report's subsystems, reply with: > > #syz set subsystems: new-subsystem > > (See the list of subsystem names on the web dashboard) > > > > If the report is a duplicate of another one, reply with: > > #syz dup: exact-subject-of-another-report > > > > If you want to undo deduplication, reply with: > > #syz undup > > Thanks for the bug report. That warning pops if you try to remove a > /proc entry and it doesn't exist. > > My suspicion here is that the initial creation of that entry failed for > some reason and the nfsd code just ignored that error. This failure is common and triggered by fault injection during netns initialisation. You can see that in the syzbot's log: https://syzkaller.appspot.com/x/log.txt?x=151e9318580000 I fixed a similar one in 24457f1be29f ("nfs: Handle error of rpc_proc_register() in nfs_net_init()."). > In fact, > nfsd_proc_stat_init() ignores the return code from svc_proc_register(). > If we fix that, then this probably would have failed gracefully at > net_init time. I'll see about spinning up a patch to fix that.
