Re: [syzbot] [bpf?] [net?] kernel BUG in pskb_expand_head (2)

[Alexei Starovoitov]

John,

could you please check whether your pending sockmap patches
address this issue as well or it's a new one?

On Wed, May 10, 2023 at 5:29 AM syzbot
<syzbot+78bac731178aabdb6307@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
>
> Hello,
>
> syzbot found the following issue on:
>
> HEAD commit:    ed23734c23d2 Merge tag 'net-6.4-rc1' of git://git.kernel.o..
> git tree:       net
> console output: https://syzkaller.appspot.com/x/log.txt?x=10ecc3b0280000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=87f9126139666d37
> dashboard link: https://syzkaller.appspot.com/bug?extid=78bac731178aabdb6307
> 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.
>
> Downloadable assets:
> disk image: https://storage.googleapis.com/syzbot-assets/d103acfdbd1d/disk-ed23734c.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/4448a632b1df/vmlinux-ed23734c.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/758a66ebff4f/bzImage-ed23734c.xz
>
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+78bac731178aabdb6307@xxxxxxxxxxxxxxxxxxxxxxxxx
>
> ------------[ cut here ]------------
> kernel BUG at net/core/skbuff.c:2047!
> invalid opcode: 0000 [#1] PREEMPT SMP KASAN
> CPU: 0 PID: 16973 Comm: syz-executor.5 Not tainted 6.3.0-syzkaller-13379-ged23734c23d2 #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/14/2023
> RIP: 0010:pskb_expand_head+0xc4a/0x1170 net/core/skbuff.c:2047
> Code: 8d 75 ff e9 0f fe ff ff e8 b3 20 7c f9 48 c7 c6 40 cb 5d 8b 4c 89 f7 e8 14 a4 b7 f9 0f 0b e8 9d 20 7c f9 0f 0b e8 96 20 7c f9 <0f> 0b e8 8f 20 7c f9 48 89 df e8 87 50 ff ff e9 75 f5 ff ff e8 7d
> RSP: 0018:ffffc90003797818 EFLAGS: 00010216
> RAX: 0000000000001b49 RBX: ffff888015b06870 RCX: ffffc900056ba000
> RDX: 0000000000040000 RSI: ffffffff8808244a RDI: 0000000000000005
> RBP: 0000000000000002 R08: 0000000000000005 R09: 0000000000000001
> R10: 0000000000000002 R11: 1ffff110040ad08a R12: 0000000000000820
> R13: dffffc0000000000 R14: ffff888015b06940 R15: 0000000000000000
> FS:  00007f4a686bb700(0000) GS:ffff8880b9800000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 0000001b2e124000 CR3: 000000007314b000 CR4: 00000000003506f0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> Call Trace:
>  <TASK>
>  skb_ensure_writable net/core/skbuff.c:6001 [inline]
>  skb_ensure_writable+0x2cb/0x450 net/core/skbuff.c:5993
>  __bpf_try_make_writable net/core/filter.c:1658 [inline]
>  sk_skb_try_make_writable net/core/filter.c:1881 [inline]
>  ____sk_skb_pull_data net/core/filter.c:1895 [inline]
>  sk_skb_pull_data+0x8b/0xa0 net/core/filter.c:1884
>  bpf_prog_53daab6e9cefb4fc+0x1a/0x1c
>  bpf_dispatcher_nop_func include/linux/bpf.h:1168 [inline]
>  __bpf_prog_run include/linux/filter.h:600 [inline]
>  bpf_prog_run include/linux/filter.h:607 [inline]
>  bpf_prog_run_pin_on_cpu include/linux/filter.h:624 [inline]
>  sk_psock_verdict_recv+0x36d/0x7a0 net/core/skmsg.c:1201
>  tcp_read_skb+0x177/0x670 net/ipv4/tcp.c:1773
>  sk_psock_verdict_data_ready+0xad/0xd0 net/core/skmsg.c:1220
>  tcp_data_ready+0x10a/0x520 net/ipv4/tcp_input.c:5006
>  tcp_rcv_established+0x194f/0x1f90 net/ipv4/tcp_input.c:5986
>  tcp_v4_do_rcv+0x65a/0x9c0 net/ipv4/tcp_ipv4.c:1721
>  sk_backlog_rcv include/net/sock.h:1113 [inline]
>  __release_sock+0x133/0x3b0 net/core/sock.c:2917
>  release_sock+0x58/0x1b0 net/core/sock.c:3484
>  tcp_sendmsg+0x3a/0x50 net/ipv4/tcp.c:1486
>  inet_sendmsg+0x9d/0xe0 net/ipv4/af_inet.c:825
>  sock_sendmsg_nosec net/socket.c:724 [inline]
>  sock_sendmsg+0xde/0x190 net/socket.c:747
>  __sys_sendto+0x23a/0x340 net/socket.c:2144
>  __do_sys_sendto net/socket.c:2156 [inline]
>  __se_sys_sendto net/socket.c:2152 [inline]
>  __x64_sys_sendto+0xe1/0x1b0 net/socket.c:2152
>  do_syscall_x64 arch/x86/entry/common.c:50 [inline]
>  do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80
>  entry_SYSCALL_64_after_hwframe+0x63/0xcd
> RIP: 0033:0x7f4a6788c169
> Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 f1 19 00 00 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
> RSP: 002b:00007f4a686bb168 EFLAGS: 00000246 ORIG_RAX: 000000000000002c
> RAX: ffffffffffffffda RBX: 00007f4a679abf80 RCX: 00007f4a6788c169
> RDX: 0000000000000001 RSI: 00000000200000c0 RDI: 0000000000000003
> RBP: 00007f4a678e7ca1 R08: 0000000000000000 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
> R13: 00007fff06f0778f R14: 00007f4a686bb300 R15: 0000000000022000
>  </TASK>
> Modules linked in:
> ---[ end trace 0000000000000000 ]---
> RIP: 0010:pskb_expand_head+0xc4a/0x1170 net/core/skbuff.c:2047
> Code: 8d 75 ff e9 0f fe ff ff e8 b3 20 7c f9 48 c7 c6 40 cb 5d 8b 4c 89 f7 e8 14 a4 b7 f9 0f 0b e8 9d 20 7c f9 0f 0b e8 96 20 7c f9 <0f> 0b e8 8f 20 7c f9 48 89 df e8 87 50 ff ff e9 75 f5 ff ff e8 7d
> RSP: 0018:ffffc90003797818 EFLAGS: 00010216
> RAX: 0000000000001b49 RBX: ffff888015b06870 RCX: ffffc900056ba000
> RDX: 0000000000040000 RSI: ffffffff8808244a RDI: 0000000000000005
> RBP: 0000000000000002 R08: 0000000000000005 R09: 0000000000000001
> R10: 0000000000000002 R11: 1ffff110040ad08a R12: 0000000000000820
> R13: dffffc0000000000 R14: ffff888015b06940 R15: 0000000000000000
> FS:  00007f4a686bb700(0000) GS:ffff8880b9800000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 00007feddbf47100 CR3: 000000007314b000 CR4: 00000000003506f0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
>
>
> ---
> 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 bug is already fixed, let syzbot know by replying with:
> #syz fix: exact-commit-title
>
> If you want to change bug's subsystems, reply with:
> #syz set subsystems: new-subsystem
> (See the list of subsystem names on the web dashboard)
>
> If the bug is a duplicate of another bug, reply with:
> #syz dup: exact-subject-of-another-report
>
> If you want to undo deduplication, reply with:
> #syz undup
>