On Fri, Apr 30, 2021 at 3:19 PM syzbot <syzbot+959223586843e69a2674@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote: > > Hello, > > syzbot found the following issue on: > > HEAD commit: 2a1d7946 Merge tag 'for-linus' of git://git.kernel.org/pub.. > git tree: upstream > console output: https://syzkaller.appspot.com/x/log.txt?x=159af1c1d00000 > kernel config: https://syzkaller.appspot.com/x/.config?x=9404cfa686df2c05 > dashboard link: https://syzkaller.appspot.com/bug?extid=959223586843e69a2674 > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=11613d71d00000 > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=12be674dd00000 > > The issue was bisected to: > > commit 997acaf6b4b59c6a9c259740312a69ea549cc684 > Author: Mark Rutland <mark.rutland@xxxxxxx> > Date: Mon Jan 11 15:37:07 2021 +0000 > > lockdep: report broken irq restoration > > bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=17c36a5dd00000 > final oops: https://syzkaller.appspot.com/x/report.txt?x=14236a5dd00000 > console output: https://syzkaller.appspot.com/x/log.txt?x=10236a5dd00000 > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > Reported-by: syzbot+959223586843e69a2674@xxxxxxxxxxxxxxxxxxxxxxxxx > Fixes: 997acaf6b4b5 ("lockdep: report broken irq restoration") > > ====================================================== > WARNING: possible circular locking dependency detected > 5.12.0-rc8-syzkaller #0 Not tainted > ------------------------------------------------------ > syz-executor044/8536 is trying to acquire lock: > ffff8880183933a0 (slock-AF_INET6){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:354 [inline] > ffff8880183933a0 (slock-AF_INET6){+.-.}-{2:2}, at: sctp_addr_wq_timeout_handler+0x1a1/0x550 net/sctp/protocol.c:666 > > but task is already holding lock: > ffffffff8d659620 (&net->sctp.addr_wq_lock){+.-.}-{2:2}, at: spin_lock_bh include/linux/spinlock.h:359 [inline] > ffffffff8d659620 (&net->sctp.addr_wq_lock){+.-.}-{2:2}, at: sctp_addr_wq_timeout_handler+0x38/0x550 net/sctp/protocol.c:626 > > which lock already depends on the new lock. > > > the existing dependency chain (in reverse order) is: > > -> #1 (&net->sctp.addr_wq_lock){+.-.}-{2:2}: > __raw_spin_lock_bh include/linux/spinlock_api_smp.h:135 [inline] > _raw_spin_lock_bh+0x2f/0x40 kernel/locking/spinlock.c:175 > spin_lock_bh include/linux/spinlock.h:359 [inline] > sctp_destroy_sock+0x204/0x440 net/sctp/socket.c:5028 > sctp_v6_destroy_sock+0x11/0x20 net/sctp/socket.c:9528 > sk_common_release+0x64/0x390 net/core/sock.c:3264 > sctp_close+0x4da/0x940 net/sctp/socket.c:1531 > inet_release+0x12e/0x280 net/ipv4/af_inet.c:431 > inet6_release+0x4c/0x70 net/ipv6/af_inet6.c:478 > __sock_release+0xcd/0x280 net/socket.c:599 > sock_close+0x18/0x20 net/socket.c:1258 > __fput+0x288/0x920 fs/file_table.c:280 > task_work_run+0xdd/0x1a0 kernel/task_work.c:140 > exit_task_work include/linux/task_work.h:30 [inline] > do_exit+0xbfc/0x2a60 kernel/exit.c:825 > do_group_exit+0x125/0x310 kernel/exit.c:922 > __do_sys_exit_group kernel/exit.c:933 [inline] > __se_sys_exit_group kernel/exit.c:931 [inline] > __x64_sys_exit_group+0x3a/0x50 kernel/exit.c:931 > do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 > entry_SYSCALL_64_after_hwframe+0x44/0xae > > -> #0 (slock-AF_INET6){+.-.}-{2:2}: > check_prev_add kernel/locking/lockdep.c:2937 [inline] > check_prevs_add kernel/locking/lockdep.c:3060 [inline] > validate_chain kernel/locking/lockdep.c:3675 [inline] > __lock_acquire+0x2b14/0x54c0 kernel/locking/lockdep.c:4901 > lock_acquire kernel/locking/lockdep.c:5511 [inline] > lock_acquire+0x1ab/0x740 kernel/locking/lockdep.c:5476 > __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline] > _raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:151 > spin_lock include/linux/spinlock.h:354 [inline] > sctp_addr_wq_timeout_handler+0x1a1/0x550 net/sctp/protocol.c:666 > call_timer_fn+0x1a5/0x6b0 kernel/time/timer.c:1431 > expire_timers kernel/time/timer.c:1476 [inline] > __run_timers.part.0+0x67c/0xa50 kernel/time/timer.c:1745 > __run_timers kernel/time/timer.c:1726 [inline] > run_timer_softirq+0xb3/0x1d0 kernel/time/timer.c:1758 > __do_softirq+0x29b/0x9f6 kernel/softirq.c:345 > invoke_softirq kernel/softirq.c:221 [inline] > __irq_exit_rcu kernel/softirq.c:422 [inline] > irq_exit_rcu+0x134/0x200 kernel/softirq.c:434 > sysvec_apic_timer_interrupt+0x93/0xc0 arch/x86/kernel/apic/apic.c:1100 > asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:632 > __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:161 [inline] > _raw_spin_unlock_irqrestore+0x38/0x70 kernel/locking/spinlock.c:191 > __debug_check_no_obj_freed lib/debugobjects.c:997 [inline] > debug_check_no_obj_freed+0x20c/0x420 lib/debugobjects.c:1018 > slab_free_hook mm/slub.c:1554 [inline] > slab_free_freelist_hook+0x147/0x210 mm/slub.c:1600 > slab_free mm/slub.c:3161 [inline] > kmem_cache_free+0x8a/0x740 mm/slub.c:3177 > free_fs_struct fs/fs_struct.c:92 [inline] > exit_fs+0x123/0x170 fs/fs_struct.c:108 > do_exit+0xbca/0x2a60 kernel/exit.c:821 > do_group_exit+0x125/0x310 kernel/exit.c:922 > __do_sys_exit_group kernel/exit.c:933 [inline] > __se_sys_exit_group kernel/exit.c:931 [inline] > __x64_sys_exit_group+0x3a/0x50 kernel/exit.c:931 > do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 > entry_SYSCALL_64_after_hwframe+0x44/0xae > > other info that might help us debug this: > > Possible unsafe locking scenario: > > CPU0 CPU1 > ---- ---- > lock(&net->sctp.addr_wq_lock); > lock(slock-AF_INET6); > lock(&net->sctp.addr_wq_lock); > lock(slock-AF_INET6); Unfortunately, Commit b166a20b0738 ("net/sctp: fix race condition in sctp_destroy_sock") introduced this, and had to be reverted. I'm thinking to fix it by delaying the auto_asconf until doing bind, which makes more sense, as auto_asconf requires an ANY addr bind: diff --git a/net/sctp/socket.c b/net/sctp/socket.c index a710917c5ac7..4ae428f2f2c5 100644 --- a/net/sctp/socket.c +++ b/net/sctp/socket.c @@ -357,6 +357,18 @@ static struct sctp_af *sctp_sockaddr_af(struct sctp_sock *opt, return af; } +static void sctp_auto_asconf_init(struct sctp_sock *sp) +{ + struct net *net = sock_net(&sp->inet.sk); + + if (net->sctp.default_auto_asconf) { + spin_lock(&net->sctp.addr_wq_lock); + list_add_tail(&sp->auto_asconf_list, &net->sctp.auto_asconf_splist); + spin_unlock(&net->sctp.addr_wq_lock); + sp->do_auto_asconf = 1; + } +} + /* Bind a local address either to an endpoint or to an association. */ static int sctp_do_bind(struct sock *sk, union sctp_addr *addr, int len) { @@ -418,8 +430,10 @@ static int sctp_do_bind(struct sock *sk, union sctp_addr *addr, int len) return -EADDRINUSE; /* Refresh ephemeral port. */ - if (!bp->port) + if (!bp->port) { bp->port = inet_sk(sk)->inet_num; + sctp_auto_asconf_init(sp); + } /* Add the address to the bind address list. * Use GFP_ATOMIC since BHs will be disabled. @@ -4993,19 +5007,6 @@ static int sctp_init_sock(struct sock *sk) sk_sockets_allocated_inc(sk); sock_prot_inuse_add(net, sk->sk_prot, 1); - /* Nothing can fail after this block, otherwise - * sctp_destroy_sock() will be called without addr_wq_lock held - */ - if (net->sctp.default_auto_asconf) { - spin_lock(&sock_net(sk)->sctp.addr_wq_lock); - list_add_tail(&sp->auto_asconf_list, - &net->sctp.auto_asconf_splist); - sp->do_auto_asconf = 1; - spin_unlock(&sock_net(sk)->sctp.addr_wq_lock); - } else { - sp->do_auto_asconf = 0; - } - local_bh_enable(); return 0; @@ -9401,6 +9402,8 @@ static int sctp_sock_migrate(struct sock *oldsk, struct sock *newsk, return err; } + sctp_auto_asconf_init(newsp); + /* Move any messages in the old socket's receive queue that are for the * peeled off association to the new socket's receive queue. */ -- 2.18.1 Thanks. > > *** DEADLOCK *** > > 2 locks held by syz-executor044/8536: > #0: ffffc90000007d78 ((&net->sctp.addr_wq_timer)){+.-.}-{0:0}, at: lockdep_copy_map include/linux/lockdep.h:35 [inline] > #0: ffffc90000007d78 ((&net->sctp.addr_wq_timer)){+.-.}-{0:0}, at: call_timer_fn+0xd5/0x6b0 kernel/time/timer.c:1421 > #1: ffffffff8d659620 (&net->sctp.addr_wq_lock){+.-.}-{2:2}, at: spin_lock_bh include/linux/spinlock.h:359 [inline] > #1: ffffffff8d659620 (&net->sctp.addr_wq_lock){+.-.}-{2:2}, at: sctp_addr_wq_timeout_handler+0x38/0x550 net/sctp/protocol.c:626 > > stack backtrace: > CPU: 0 PID: 8536 Comm: syz-executor044 Not tainted 5.12.0-rc8-syzkaller #0 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 > Call Trace: > <IRQ> > __dump_stack lib/dump_stack.c:79 [inline] > dump_stack+0x141/0x1d7 lib/dump_stack.c:120 > check_noncircular+0x25f/0x2e0 kernel/locking/lockdep.c:2128 > check_prev_add kernel/locking/lockdep.c:2937 [inline] > check_prevs_add kernel/locking/lockdep.c:3060 [inline] > validate_chain kernel/locking/lockdep.c:3675 [inline] > __lock_acquire+0x2b14/0x54c0 kernel/locking/lockdep.c:4901 > lock_acquire kernel/locking/lockdep.c:5511 [inline] > lock_acquire+0x1ab/0x740 kernel/locking/lockdep.c:5476 > __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline] > _raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:151 > spin_lock include/linux/spinlock.h:354 [inline] > sctp_addr_wq_timeout_handler+0x1a1/0x550 net/sctp/protocol.c:666 > call_timer_fn+0x1a5/0x6b0 kernel/time/timer.c:1431 > expire_timers kernel/time/timer.c:1476 [inline] > __run_timers.part.0+0x67c/0xa50 kernel/time/timer.c:1745 > __run_timers kernel/time/timer.c:1726 [inline] > run_timer_softirq+0xb3/0x1d0 kernel/time/timer.c:1758 > __do_softirq+0x29b/0x9f6 kernel/softirq.c:345 > invoke_softirq kernel/softirq.c:221 [inline] > __irq_exit_rcu kernel/softirq.c:422 [inline] > irq_exit_rcu+0x134/0x200 kernel/softirq.c:434 > sysvec_apic_timer_interrupt+0x93/0xc0 arch/x86/kernel/apic/apic.c:1100 > </IRQ> > asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:632 > RIP: 0010:__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:161 [inline] > RIP: 0010:_raw_spin_unlock_irqrestore+0x38/0x70 kernel/locking/spinlock.c:191 > Code: 74 24 10 e8 4a f9 53 f8 48 89 ef e8 82 af 54 f8 81 e3 00 02 00 00 75 25 9c 58 f6 c4 02 75 2d 48 85 db 74 01 fb bf 01 00 00 00 <e8> 63 7d 48 f8 65 8b 05 0c 48 fc 76 85 c0 74 0a 5b 5d c3 e8 d0 3c > RSP: 0018:ffffc9000173fc50 EFLAGS: 00000206 > RAX: 0000000000000002 RBX: 0000000000000200 RCX: 1ffffffff1b89e11 > RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000001 > RBP: ffffffff9006cf00 R08: 0000000000000001 R09: 0000000000000001 > R10: ffffffff8179e4c8 R11: 000000000000003f R12: 1ffffffff200d9df > R13: 0000000000000000 R14: dead000000000100 R15: dffffc0000000000 > __debug_check_no_obj_freed lib/debugobjects.c:997 [inline] > debug_check_no_obj_freed+0x20c/0x420 lib/debugobjects.c:1018 > slab_free_hook mm/slub.c:1554 [inline] > slab_free_freelist_hook+0x147/0x210 mm/slub.c:1600 > slab_free mm/slub.c:3161 [inline] > kmem_cache_free+0x8a/0x740 mm/slub.c:3177 > free_fs_struct fs/fs_struct.c:92 [inline] > exit_fs+0x123/0x170 fs/fs_struct.c:108 > do_exit+0xbca/0x2a60 kernel/exit.c:821 > do_group_exit+0x125/0x310 kernel/exit.c:922 > __do_sys_exit_group kernel/exit.c:933 [inline] > __se_sys_exit_group kernel/exit.c:931 [inline] > __x64_sys_exit_group+0x3a/0x50 kernel/exit.c:931 > do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 > entry_SYSCALL_64_after_hwframe+0x44/0xae > RIP: 0033:0x43ea79 > Code: Unable to access opcode bytes at RIP 0x43ea4f. > RSP: 002b:00007ffdbc348058 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 > RAX: ffffffffffffffda RBX: 00000000004b0330 RCX: 000000000043ea79 > RDX: 000000000000003c RSI: 00000000000000e7 RDI: 0000000000000000 > RBP: 0000000000000000 R08: ffffffffffffffc0 R09: 0000000000000001 > R10: 0000000000000001 R11: 0000000000000246 R12: 00000000004b0330 > R13: 0000000000000001 R14: 0000000000000000 R15: 0000000000000001 > > > --- > 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. > For information about bisection process see: https://goo.gl/tpsmEJ#bisection > syzbot can test patches for this issue, for details see: > https://goo.gl/tpsmEJ#testing-patches
