Subject: Re: [syzbot] WARNING in sk_stream_kill_queues (8)

From: John Fastabend <[email-masked]>
Date: Wed, 29 Jun 2022 11:13:59 -0700

Eric Dumazet wrote:
> On Wed, Jun 29, 2022 at 7:45 PM Eric Dumazet <[email-masked]> wrote:
> >
> > On Wed, Jun 29, 2022 at 7:41 PM syzbot
> > <[email-masked]> wrote:
> > >
> > > Hello,
> > >
> > > syzbot found the following issue on:
> > >
> > > HEAD commit:    aab35c3d5112 Add linux-next specific files for 20220627
> > > git tree:       linux-next
> > > console+strace: https://syzkaller.appspot.com/x/log.txt?x=126fef90080000
> > > kernel config:  https://syzkaller.appspot.com/x/.config?x=6a874f114a1e4a6b
> > > dashboard link: https://syzkaller.appspot.com/bug?extid=a0e6f8738b58f7654417
> > > 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=14ae0c98080000
> > > C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=145124f4080000
> > >
> > > IMPORTANT: if you fix the issue, please add the following tag to the commit:
> > > Reported-by: [email-masked]
> > >
> > > nf_conntrack: default automatic helper assignment has been turned off for security reasons and CT-based firewall rule not found. Use the iptables CT target to attach helpers instead.
> > > ------------[ cut here ]------------
> > > WARNING: CPU: 1 PID: 3601 at net/core/stream.c:205 sk_stream_kill_queues+0x2ee/0x3d0 net/core/stream.c:205
> > > Modules linked in:
> > > CPU: 1 PID: 3601 Comm: syz-executor340 Not tainted 5.19.0-rc4-next-20220627-syzkaller #0
> > > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
> > > RIP: 0010:sk_stream_kill_queues+0x2ee/0x3d0 net/core/stream.c:205
> > > Code: 03 0f b6 04 02 84 c0 74 08 3c 03 0f 8e ec 00 00 00 8b ab 28 02 00 00 e9 60 ff ff ff e8 3b 9a 29 fa 0f 0b eb 97 e8 32 9a 29 fa <0f> 0b eb a0 e8 29 9a 29 fa 0f 0b e9 6a fe ff ff e8 0d a1 75 fa e9
> > > RSP: 0018:ffffc90002e6fbf0 EFLAGS: 00010293
> > > RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
> > > RDX: ffff88801e90ba80 RSI: ffffffff87511cce RDI: 0000000000000005
> > > RBP: 0000000000000b00 R08: 0000000000000005 R09: 0000000000000000
> > > R10: 0000000000000b00 R11: 0000000000000004 R12: ffff88801e0c8e28
> > > R13: ffffffff913121c0 R14: ffff88801e0c8c28 R15: ffff88801e0c8db8
> > > FS:  0000000000000000(0000) GS:ffff8880b9b00000(0000) knlGS:0000000000000000
> > > CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> > > CR2: 000000000045b630 CR3: 000000000ba8e000 CR4: 00000000003506e0
> > > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> > > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> > > Call Trace:
> > >  <TASK>
> > >  inet_csk_destroy_sock+0x1a5/0x440 net/ipv4/inet_connection_sock.c:1013
> > >  __tcp_close+0xb92/0xf50 net/ipv4/tcp.c:2963
> > >  tcp_close+0x29/0xc0 net/ipv4/tcp.c:2975
> > >  inet_release+0x12e/0x270 net/ipv4/af_inet.c:428
> > >  __sock_release+0xcd/0x280 net/socket.c:650
> > >  sock_close+0x18/0x20 net/socket.c:1365
> > >  __fput+0x277/0x9d0 fs/file_table.c:317
> > >  task_work_run+0xdd/0x1a0 kernel/task_work.c:177
> > >  exit_task_work include/linux/task_work.h:38 [inline]
> > >  do_exit+0xaf1/0x29f0 kernel/exit.c:795
> > >  do_group_exit+0xd2/0x2f0 kernel/exit.c:925
> > >  __do_sys_exit_group kernel/exit.c:936 [inline]
> > >  __se_sys_exit_group kernel/exit.c:934 [inline]
> > >  __x64_sys_exit_group+0x3a/0x50 kernel/exit.c:934
> > >  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+0x46/0xb0
> > > RIP: 0033:0x7f080e760989
> > > Code: Unable to access opcode bytes at RIP 0x7f080e76095f.
> > > RSP: 002b:00007ffcee785818 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
> > > RAX: ffffffffffffffda RBX: 00007f080e7d4270 RCX: 00007f080e760989
> > > RDX: 000000000000003c RSI: 00000000000000e7 RDI: 0000000000000000
> > > RBP: 0000000000000000 R08: ffffffffffffffc0 R09: 0000000000000010
> > > R10: 0000000000000010 R11: 0000000000000246 R12: 00007f080e7d4270
> > > R13: 0000000000000001 R14: 0000000000000000 R15: 0000000000000001
> > >  </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 [email-masked].
> > >
> > > syzbot will keep track of this issue. See:
> > > https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
> > > syzbot can test patches for this issue, for details see:
> > > https://goo.gl/tpsmEJ#testing-patches
> >
> > Stanislav has bisected the issue to:
> >
> > commit 965b57b469a589d64d81b1688b38dcb537011bb0
> > Author: Cong Wang <[email-masked]>
> > Date:   Wed Jun 15 09:20:12 2022 -0700
> >
> >     net: Introduce a new proto_ops ->read_skb()
> >
> >     Currently both splice() and sockmap use ->read_sock() to
> >     read skb from receive queue, but for sockmap we only read
> >     one entire skb at a time, so ->read_sock() is too conservative
> >     to use. Introduce a new proto_ops ->read_skb() which supports
> >     this sematic, with this we can finally pass the ownership of
> >     skb to recv actors.
> >
> >     For non-TCP protocols, all ->read_sock() can be simply
> >     converted to ->read_skb().
> >
> >     Signed-off-by: Cong Wang <[email-masked]>
> >     Signed-off-by: Daniel Borkmann <[email-masked]>
> >     Reviewed-by: John Fastabend <[email-masked]>
> >     Link: https://lore.kernel.org/bpf/[email-masked]
> 
> Repro is doing something like:
> 
> 
> mmap(0x1ffff000, 4096, PROT_NONE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS,
> -1, 0) = 0x1ffff000
> mmap(0x20000000, 16777216, PROT_READ|PROT_WRITE|PROT_EXEC,
> MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x20000000
> mmap(0x21000000, 4096, PROT_NONE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS,
> -1, 0) = 0x21000000
> socket(AF_INET, SOCK_STREAM, IPPROTO_IP) = 3
> bpf(BPF_PROG_LOAD, {prog_type=BPF_PROG_TYPE_SK_SKB, insn_cnt=4,
> insns=0x20000040, license="GPL", log_level=4, log_size=64912,
> log_buf="", kern_version=KERNEL_VERSION(0, 0, 0), prog_flags=0,
> prog_name="", prog_ifindex=0,
> expected_attach_type=BPF_CGROUP_INET_INGRESS}, 72) = 4
> bpf(BPF_MAP_CREATE, {map_type=BPF_MAP_TYPE_SOCKHASH, key_size=4,
> value_size=4, max_entries=18, map_flags=0, inner_map_fd=-1,
> map_name="", map_ifindex=0, btf_fd=-1, btf_key_type_id=0,
> btf_value_type_id=0, btf_vmlinux_value_type_id=0, map_extra=0}, 72) =
> 5
> bpf(BPF_PROG_ATTACH, {target_fd=5, attach_bpf_fd=4,
> attach_type=BPF_SK_SKB_STREAM_VERDICT, attach_flags=0}, 16) = 0
> bind(3, {sa_family=AF_INET, sin_port=htons(20000),
> sin_addr=inet_addr("224.0.0.2")}, 16) = 0
> sendto(3, NULL, 0, MSG_OOB|MSG_SENDPAGE_NOTLAST|MSG_FASTOPEN,
> {sa_family=AF_INET, sin_port=htons(20000),
> sin_addr=inet_addr("0.0.0.0")}, 16) = 0
> bpf(BPF_MAP_UPDATE_ELEM, {map_fd=5, key=0x200002c0, value=0x20000340,
> flags=BPF_ANY}, 32) = 0
> shutdown(3, SHUT_WR)                    = 0
> exit_group(0)                           = ?

Thanks Eric, Stanislav for the bisect. I'll take a look this afternoon.