Eric Dumazet wrote: > On Wed, Dec 7, 2022 at 7:38 AM John Fastabend <john.fastabend@xxxxxxxxx> wrote: > > > > syzbot wrote: > > > Hello, > > > > > > syzbot found the following issue on: > > > > > > HEAD commit: 6a30d3e3491d selftests: net: Use "grep -E" instead of "egr.. > > > git tree: net > > > console+strace: https://syzkaller.appspot.com/x/log.txt?x=1576b11d880000 > > > kernel config: https://syzkaller.appspot.com/x/.config?x=cc4b2e0a8e8a8366 > > > dashboard link: https://syzkaller.appspot.com/bug?extid=04c21ed96d861dccc5cd > > > 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=14e1656b880000 > > > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1077da23880000 > > > > > > Downloadable assets: > > > disk image: https://storage.googleapis.com/syzbot-assets/bbee3d5fc908/disk-6a30d3e3.raw.xz > > > vmlinux: https://storage.googleapis.com/syzbot-assets/bf9e258de70e/vmlinux-6a30d3e3.xz > > > kernel image: https://storage.googleapis.com/syzbot-assets/afaa6696b9e0/bzImage-6a30d3e3.xz > > > > > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > > > Reported-by: syzbot+04c21ed96d861dccc5cd@xxxxxxxxxxxxxxxxxxxxxxxxx > > > > > > BUG: TASK stack guard page was hit at ffffc90003cd7fa8 (stack is ffffc90003cd8000..ffffc90003ce0000) > > > stack guard page: 0000 [#1] PREEMPT SMP KASAN > > > CPU: 0 PID: 3636 Comm: syz-executor238 Not tainted 6.1.0-rc7-syzkaller-00135-g6a30d3e3491d #0 > > > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022 > > > RIP: 0010:mark_lock.part.0+0x26/0x1910 kernel/locking/lockdep.c:4593 > > > Code: 00 00 00 00 41 57 41 56 41 55 41 89 d5 48 ba 00 00 00 00 00 fc ff df 41 54 49 89 f4 55 53 48 81 ec 38 01 00 00 48 8d 5c 24 38 <48> 89 3c 24 48 c7 44 24 38 b3 8a b5 41 48 c1 eb 03 48 c7 44 24 40 > > > RSP: 0018:ffffc90003cd7fb8 EFLAGS: 00010096 > > > RAX: 0000000000000004 RBX: ffffc90003cd7ff0 RCX: ffffffff8162a7bf > > > RDX: dffffc0000000000 RSI: ffff88801f65e238 RDI: ffff88801f65d7c0 > > > RBP: ffff88801f65e25a R08: 0000000000000000 R09: ffffffff910f4aff > > > R10: fffffbfff221e95f R11: 0000000000000000 R12: ffff88801f65e238 > > > R13: 0000000000000002 R14: 0000000000000000 R15: 0000000000040000 > > > FS: 0000000000000000(0000) GS:ffff8880b9a00000(0000) knlGS:0000000000000000 > > > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > > > CR2: ffffc90003cd7fa8 CR3: 000000000c28e000 CR4: 00000000003506f0 > > > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > > > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > > > Call Trace: > > > <TASK> > > > mark_lock kernel/locking/lockdep.c:4598 [inline] > > > mark_usage kernel/locking/lockdep.c:4543 [inline] > > > __lock_acquire+0x847/0x56d0 kernel/locking/lockdep.c:5009 > > > lock_acquire kernel/locking/lockdep.c:5668 [inline] > > > lock_acquire+0x1e3/0x630 kernel/locking/lockdep.c:5633 > > > lock_sock_nested+0x3a/0xf0 net/core/sock.c:3447 > > > lock_sock include/net/sock.h:1721 [inline] > > > sock_map_close+0x75/0x7b0 net/core/sock_map.c:1610 > > > > I'll take a look likely something recent. > > Fact that sock_map_close can call itself seems risky. > We might issue a one time warning and keep the host alive. Agree seems better to check the condition than loop on close. I still need to figure out the bug that got into this state though. Thanks. > > diff --git a/net/core/sock_map.c b/net/core/sock_map.c > index 81beb16ab1ebfcb166f51f89a029fe1c28a629a4..a79771a6627b9b2f38ae6ce153ceff9e8c0be8d4 > 100644 > --- a/net/core/sock_map.c > +++ b/net/core/sock_map.c > @@ -1612,17 +1612,25 @@ void sock_map_close(struct sock *sk, long timeout) > psock = sk_psock_get(sk); > if (unlikely(!psock)) { > rcu_read_unlock(); > + saved_close = sk->sk_prot->close; > release_sock(sk); > - return sk->sk_prot->close(sk, timeout); > + } else { > + saved_close = psock->saved_close; > + sock_map_remove_links(sk, psock); > + rcu_read_unlock(); > + sk_psock_stop(psock); > + release_sock(sk); > + cancel_work_sync(&psock->work); > + sk_psock_put(sk, psock); > + } > + /* Make sure we do not recurse to us. > + * This is a bug, we can leak the socket instead > + * of crashing on a stack overflow. > + */ > + if (saved_close == sock_map_close) { > + WARN_ON_ONCE(1); > + return; > } > - > - saved_close = psock->saved_close; > - sock_map_remove_links(sk, psock); > - rcu_read_unlock(); > - sk_psock_stop(psock); > - release_sock(sk); > - cancel_work_sync(&psock->work); > - sk_psock_put(sk, psock); > saved_close(sk, timeout); > } > EXPORT_SYMBOL_GPL(sock_map_close);
