Re: [syzbot] general protection fault in kernel_accept (5)

[Xin Long]

On Tue, Sep 27, 2022 at 10:26 AM Jakub Kicinski <kuba@xxxxxxxxxx> wrote:
>
> Adding TIPC
>
> On Tue, 27 Sep 2022 01:49:38 -0700 syzbot wrote:
> > Hello,
> >
> > syzbot found the following issue on:
> >
> > HEAD commit:    bf682942cd26 Merge tag 'scsi-fixes' of git://git.kernel.or..
> > git tree:       upstream
> > console output: https://syzkaller.appspot.com/x/log.txt?x=117fc3ac880000
> > kernel config:  https://syzkaller.appspot.com/x/.config?x=7db7ad17eb14cb7
> > dashboard link: https://syzkaller.appspot.com/bug?extid=c5ce866a8d30f4be0651
> > compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
> >
> > Unfortunately, I don't have any reproducer for this issue yet.
> >
> > IMPORTANT: if you fix the issue, please add the following tag to the commit:
> > Reported-by: syzbot+c5ce866a8d30f4be0651@xxxxxxxxxxxxxxxxxxxxxxxxx
> >
> > general protection fault, probably for non-canonical address 0xdffffc0000000001: 0000 [#1] PREEMPT SMP KASAN
> > KASAN: null-ptr-deref in range [0x0000000000000008-0x000000000000000f]
> > CPU: 3 PID: 12841 Comm: kworker/u16:2 Not tainted 6.0.0-rc6-syzkaller-00210-gbf682942cd26 #0
> > Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.14.0-2 04/01/2014
> > Workqueue: tipc_rcv tipc_topsrv_accept
> > RIP: 0010:kernel_accept+0x22d/0x350 net/socket.c:3487
> > Code: 48 89 fa 48 c1 ea 03 80 3c 02 00 0f 85 e3 00 00 00 48 b8 00 00 00 00 00 fc ff df 48 8b 5b 20 48 8d 7b 08 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f 85 ee 00 00 00 48 8b 7b 08 e8 a0 36 1c fa e8 8b ff
> > RSP: 0018:ffffc9000494fc28 EFLAGS: 00010202
> > RAX: dffffc0000000000 RBX: 0000000000000000 RCX: 0000000000000000
> > RDX: 0000000000000001 RSI: ffffffff874c37b2 RDI: 0000000000000008
> > RBP: 0000000000000000 R08: 0000000000000005 R09: 0000000000000000
> > R10: 0000000000000000 R11: 0000000000000449 R12: 0000000000000000
> > R13: ffff888027a7b980 R14: ffff888028bc08e0 R15: 1ffff92000929f90
> > FS:  0000000000000000(0000) GS:ffff88802cb00000(0000) knlGS:0000000000000000
> > CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> > CR2: 00007fa6e1a8c920 CR3: 000000004bba0000 CR4: 0000000000150ee0
> > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> > Call Trace:
> >  <TASK>
> >  tipc_topsrv_accept+0x197/0x280 net/tipc/topsrv.c:460
It seems that we should free the lsock after the worker is done:

@@ -699,8 +699,8 @@ static void tipc_topsrv_stop(struct net *net)
        __module_get(lsock->sk->sk_prot_creator->owner);
        srv->listener = NULL;
        spin_unlock_bh(&srv->idr_lock);
-       sock_release(lsock);
        tipc_topsrv_work_stop(srv);
+       sock_release(lsock);
        idr_destroy(&srv->conn_idr);
        kfree(srv);
 }

> >  process_one_work+0x991/0x1610 kernel/workqueue.c:2289
> >  worker_thread+0x665/0x1080 kernel/workqueue.c:2436
> >  kthread+0x2e4/0x3a0 kernel/kthread.c:376
> >  ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:306
> >  </TASK>
> > Modules linked in:
> > ---[ end trace 0000000000000000 ]---
> > RIP: 0010:kernel_accept+0x22d/0x350 net/socket.c:3487
> > Code: 48 89 fa 48 c1 ea 03 80 3c 02 00 0f 85 e3 00 00 00 48 b8 00 00 00 00 00 fc ff df 48 8b 5b 20 48 8d 7b 08 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f 85 ee 00 00 00 48 8b 7b 08 e8 a0 36 1c fa e8 8b ff
> > RSP: 0018:ffffc9000494fc28 EFLAGS: 00010202
> > RAX: dffffc0000000000 RBX: 0000000000000000 RCX: 0000000000000000
> > RDX: 0000000000000001 RSI: ffffffff874c37b2 RDI: 0000000000000008
> > RBP: 0000000000000000 R08: 0000000000000005 R09: 0000000000000000
> > R10: 0000000000000000 R11: 0000000000000449 R12: 0000000000000000
> > R13: ffff888027a7b980 R14: ffff888028bc08e0 R15: 1ffff92000929f90
> > FS:  0000000000000000(0000) GS:ffff88802ca00000(0000) knlGS:0000000000000000
> > CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> > CR2: 000000c0154d8000 CR3: 000000006fb4b000 CR4: 0000000000150ee0
> > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> > ----------------
> > Code disassembly (best guess):
> >    0: 48 89 fa                mov    %rdi,%rdx
> >    3: 48 c1 ea 03             shr    $0x3,%rdx
> >    7: 80 3c 02 00             cmpb   $0x0,(%rdx,%rax,1)
> >    b: 0f 85 e3 00 00 00       jne    0xf4
> >   11: 48 b8 00 00 00 00 00    movabs $0xdffffc0000000000,%rax
> >   18: fc ff df
> >   1b: 48 8b 5b 20             mov    0x20(%rbx),%rbx
> >   1f: 48 8d 7b 08             lea    0x8(%rbx),%rdi
> >   23: 48 89 fa                mov    %rdi,%rdx
> >   26: 48 c1 ea 03             shr    $0x3,%rdx
> > * 2a: 80 3c 02 00             cmpb   $0x0,(%rdx,%rax,1) <-- trapping instruction
> >   2e: 0f 85 ee 00 00 00       jne    0x122
> >   34: 48 8b 7b 08             mov    0x8(%rbx),%rdi
> >   38: e8 a0 36 1c fa          callq  0xfa1c36dd
> >   3d: e8                      .byte 0xe8
> >   3e: 8b ff                   mov    %edi,%edi
> >
> >
> > ---
> > 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.
>