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Message-ID: <f16214e5bca925d1087f8ba6d1aa8f4cf048808b.camel@redhat.com>
Subject: Re: [syzbot] BUG: corrupted list in netif_napi_add
From:   Paolo Abeni <pabeni@redhat.com>
To:     syzbot <syzbot+62e474dd92a35e3060d8@syzkaller.appspotmail.com>,
        andrii@kernel.org, ast@kernel.org, bpf@vger.kernel.org,
        daniel@iogearbox.net, davem@davemloft.net, hawk@kernel.org,
        john.fastabend@gmail.com, kafai@fb.com, kpsingh@kernel.org,
        kuba@kernel.org, linux-kernel@vger.kernel.org,
        netdev@vger.kernel.org, songliubraving@fb.com,
        syzkaller-bugs@googlegroups.com, yhs@fb.com
Date:   Wed, 13 Oct 2021 16:41:05 +0200
In-Reply-To: <0000000000005639cd05ce3a6d4d@google.com>
References: <0000000000005639cd05ce3a6d4d@google.com>
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On Wed, 2021-10-13 at 04:40 -0700, syzbot wrote:
> Hello,
> 
> syzbot found the following issue on:
> 
> HEAD commit:    683f29b781ae Add linux-next specific files for 20211008
> git tree:       linux-next
> console output: https://syzkaller.appspot.com/x/log.txt?x=1525a614b00000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=673b3589d970c
> dashboard link: https://syzkaller.appspot.com/bug?extid=62e474dd92a35e3060d8
> 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=17c98e98b00000
> 
> IMPORTANTIMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+62e474dd92a35e3060d8@syzkaller.appspotmail.com
> 
> IPv6: ADDRCONF(NETDEV_CHANGE): vcan0: link becomes ready
> list_add double add: new=ffff888023417160, prev=ffff88807de3a050, next=ffff888023417160.
> ------------[ cut here ]------------
> kernel BUG at lib/list_debug.c:29!
> invalid opcode: 0000 [#1] PREEMPT SMP KASAN
> CPU: 0 PID: 9490 Comm: syz-executor.1 Not tainted 5.15.0-rc4-next-20211008-syzkaller #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
> RIP: 0010:__list_add_valid.cold+0x26/0x3c lib/list_debug.c:29
> Code: b1 24 c3 fa 4c 89 e1 48 c7 c7 60 56 04 8a e8 f2 8c f1 ff 0f 0b 48 89 f2 4c 89 e1 48 89 ee 48 c7 c7 a0 57 04 8a e8 db 8c f1 ff <0f> 0b 48 89 f1 48 c7 c7 20 57 04 8a 4c 89 e6 e8 c7 8c f1 ff 0f 0b
> RSP: 0018:ffffc90002c26a48 EFLAGS: 00010286
> RAX: 0000000000000058 RBX: 0000000000000040 RCX: 0000000000000000
> RDX: ffff888023263a00 RSI: ffffffff815e0d78 RDI: fffff52000584d3b
> RBP: ffff888023417160 R08: 0000000000000058 R09: 0000000000000000
> R10: ffffffff815dab5e R11: 0000000000000000 R12: ffff888023417160
> R13: ffff888023417000 R14: ffff888023417160 R15: ffff888023417160
> FS:  00007f841e9e8700(0000) GS:ffff8880b9c00000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 0000000000000000 CR3: 00000000601bd000 CR4: 00000000003506f0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> Call Trace:
>  <TASK>
>  __list_add_rcu include/linux/rculist.h:79 [inline]
>  list_add_rcu include/linux/rculist.h:106 [inline]
>  netif_napi_add+0x3fd/0x9c0 net/core/dev.c:6889
>  veth_enable_xdp_range+0x1b1/0x300 drivers/net/veth.c:1009
>  veth_enable_xdp+0x2a5/0x620 drivers/net/veth.c:1063
>  veth_xdp_set drivers/net/veth.c:1483 [inline]
>  veth_xdp+0x4d4/0x780 drivers/net/veth.c:1523
>  bond_xdp_set drivers/net/bonding/bond_main.c:5217 [inline]
>  bond_xdp+0x325/0x920 drivers/net/bonding/bond_main.c:5263
>  dev_xdp_install+0xd5/0x270 net/core/dev.c:9365
>  dev_xdp_attach+0x83d/0x1010 net/core/dev.c:9513
>  dev_change_xdp_fd+0x246/0x300 net/core/dev.c:9753
>  do_setlink+0x2fb4/0x3970 net/core/rtnetlink.c:2931
>  rtnl_group_changelink net/core/rtnetlink.c:3242 [inline]
>  __rtnl_newlink+0xc06/0x1750 net/core/rtnetlink.c:3396
>  rtnl_newlink+0x64/0xa0 net/core/rtnetlink.c:3506
>  rtnetlink_rcv_msg+0x413/0xb80 net/core/rtnetlink.c:5572
>  netlink_rcv_skb+0x153/0x420 net/netlink/af_netlink.c:2491
>  netlink_unicast_kernel net/netlink/af_netlink.c:1319 [inline]
>  netlink_unicast+0x533/0x7d0 net/netlink/af_netlink.c:1345
>  netlink_sendmsg+0x86d/0xda0 net/netlink/af_netlink.c:1916
>  sock_sendmsg_nosec net/socket.c:704 [inline]
>  sock_sendmsg+0xcf/0x120 net/socket.c:724
>  ____sys_sendmsg+0x6e8/0x810 net/socket.c:2409
>  ___sys_sendmsg+0xf3/0x170 net/socket.c:2463
>  __sys_sendmsg+0xe5/0x1b0 net/socket.c:2492
>  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+0x44/0xae
> RIP: 0033:0x7f841f2718d9
> Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 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 bc ff ff ff f7 d8 64 89 01 48
> RSP: 002b:00007f841e9e8188 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
> RAX: ffffffffffffffda RBX: 00007f841f375f60 RCX: 00007f841f2718d9
> RDX: 0000000000000000 RSI: 0000000020000140 RDI: 0000000000000003
> RBP: 00007f841f2cbcb4 R08: 0000000000000000 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
> R13: 00007ffc8978d37f R14: 00007f841e9e8300 R15: 0000000000022000
>  </TASK>
> Modules linked in:
> ---[ end trace 7281cadbc8534f23 ]---
> RIP: 0010:__list_add_valid.cold+0x26/0x3c lib/list_debug.c:29
> Code: b1 24 c3 fa 4c 89 e1 48 c7 c7 60 56 04 8a e8 f2 8c f1 ff 0f 0b 48 89 f2 4c 89 e1 48 89 ee 48 c7 c7 a0 57 04 8a e8 db 8c f1 ff <0f> 0b 48 89 f1 48 c7 c7 20 57 04 8a 4c 89 e6 e8 c7 8c f1 ff 0f 0b
> RSP: 0018:ffffc90002c26a48 EFLAGS: 00010286
> RAX: 0000000000000058 RBX: 0000000000000040 RCX: 0000000000000000
> RDX: ffff888023263a00 RSI: ffffffff815e0d78 RDI: fffff52000584d3b
> RBP: ffff888023417160 R08: 0000000000000058 R09: 0000000000000000
> R10: ffffffff815dab5e R11: 0000000000000000 R12: ffff888023417160
> R13: ffff888023417000 R14: ffff888023417160 R15: ffff888023417160
> FS:  00007f841e9e8700(0000) GS:ffff8880b9c00000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 0000000000000000 CR3: 00000000601bd000 CR4: 00000000003506f0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400

For the record: I'm wild guessing this is related to:

https://syzkaller.appspot.com/bug?extid=67f89551088ea1a6850e

(hopefully they share the same root cause)

I spent some time investigating the latter, with no real clue. This has
a repro, so I'll ask syzbot to provide more info with debug patches.

Cheers,

Paolo