Message-ID: <CADxym3YsBfQ7sbongiXhrF6KfZ9sr-6GwQkCGB=4_y2Au5V33A@mail.gmail.com>
Date: Mon, 18 Nov 2024 16:47:56 +0800
From: Menglong Dong <menglong8.dong@...il.com>
To: Paolo Abeni <pabeni@...hat.com>
Cc: dongml2@...natelecom.cn, 
	syzbot <syzbot+52fbd90f020788ec7709@...kaller.appspotmail.com>, davem@...emloft.net, 
	dsahern@...nel.org, edumazet@...gle.com, horms@...nel.org, kuba@...nel.org, 
	linux-kernel@...r.kernel.org, netdev@...r.kernel.org, 
	syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] [net?] WARNING in sk_skb_reason_drop

On Mon, Nov 18, 2024 at 4:25 PM Paolo Abeni <pabeni@...hat.com> wrote:
>
> On 11/16/24 19:32, syzbot wrote:
> > HEAD commit:    a58f00ed24b8 net: sched: cls_api: improve the error messag..
> > git tree:       net-next
> > console+strace: https://syzkaller.appspot.com/x/log.txt?x=140a735f980000
> > kernel config:  https://syzkaller.appspot.com/x/.config?x=47cb6c16bf912470
> > dashboard link: https://syzkaller.appspot.com/bug?extid=52fbd90f020788ec7709
> > compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
> > syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=132804c0580000
> > C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=14f481a7980000
> >
> > Downloadable assets:
> > disk image: https://storage.googleapis.com/syzbot-assets/d28dcea68102/disk-a58f00ed.raw.xz
> > vmlinux: https://storage.googleapis.com/syzbot-assets/8ec032ea06c6/vmlinux-a58f00ed.xz
> > kernel image: https://storage.googleapis.com/syzbot-assets/da9b8f80c783/bzImage-a58f00ed.xz
> >
> > The issue was bisected to:
> >
> > commit 82d9983ebeb871cb5abd27c12a950c14c68772e1
> > Author: Menglong Dong <menglong8.dong@...il.com>
> > Date:   Thu Nov 7 12:55:58 2024 +0000
> >
> >     net: ip: make ip_route_input_noref() return drop reasons
> >
> > bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=10ae41a7980000
> > final oops:     https://syzkaller.appspot.com/x/report.txt?x=12ae41a7980000
> > console output: https://syzkaller.appspot.com/x/log.txt?x=14ae41a7980000
> >
> > IMPORTANT: if you fix the issue, please add the following tag to the commit:
> > Reported-by: syzbot+52fbd90f020788ec7709@...kaller.appspotmail.com
> > Fixes: 82d9983ebeb8 ("net: ip: make ip_route_input_noref() return drop reasons")
> >
> > netlink: 'syz-executor371': attribute type 4 has an invalid length.
> > ------------[ cut here ]------------
> > WARNING: CPU: 0 PID: 5842 at net/core/skbuff.c:1219 __sk_skb_reason_drop net/core/skbuff.c:1216 [inline]
> > WARNING: CPU: 0 PID: 5842 at net/core/skbuff.c:1219 sk_skb_reason_drop+0x87/0x380 net/core/skbuff.c:1241
> > Modules linked in:
> > CPU: 0 UID: 0 PID: 5842 Comm: syz-executor371 Not tainted 6.12.0-rc6-syzkaller-01362-ga58f00ed24b8 #0
> > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/30/2024
> > RIP: 0010:__sk_skb_reason_drop net/core/skbuff.c:1216 [inline]
> > RIP: 0010:sk_skb_reason_drop+0x87/0x380 net/core/skbuff.c:1241
> > Code: 00 00 00 fc ff df 41 8d 9e 00 00 fc ff bf 01 00 fc ff 89 de e8 ea 9f 08 f8 81 fb 00 00 fc ff 77 3a 4c 89 e5 e8 9a 9b 08 f8 90 <0f> 0b 90 eb 5e bf 01 00 00 00 89 ee e8 c8 9f 08 f8 85 ed 0f 8e 49
> > RSP: 0018:ffffc90003d57078 EFLAGS: 00010293
> > RAX: ffffffff898c3ec6 RBX: 00000000fffbffea RCX: ffff8880347a5a00
> > RDX: 0000000000000000 RSI: 00000000fffbffea RDI: 00000000fffc0001
> > RBP: dffffc0000000000 R08: ffffffff898c3eb6 R09: 1ffff110023eb7d4
> > R10: dffffc0000000000 R11: ffffed10023eb7d5 R12: dffffc0000000000
> > R13: ffff888011f5bdc0 R14: 00000000ffffffea R15: 0000000000000000
> > FS:  000055557d41e380(0000) GS:ffff8880b8600000(0000) knlGS:0000000000000000
> > CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> > CR2: 000056519d31d608 CR3: 000000007854e000 CR4: 00000000003526f0
> > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> > Call Trace:
> >  <TASK>
> >  kfree_skb_reason include/linux/skbuff.h:1263 [inline]
> >  ip_rcv_finish_core+0xfde/0x1b50 net/ipv4/ip_input.c:424
> >  ip_list_rcv_finish net/ipv4/ip_input.c:610 [inline]
> >  ip_sublist_rcv+0x3b1/0xab0 net/ipv4/ip_input.c:636
> >  ip_list_rcv+0x42b/0x480 net/ipv4/ip_input.c:670
> >  __netif_receive_skb_list_ptype net/core/dev.c:5715 [inline]
> >  __netif_receive_skb_list_core+0x94e/0x980 net/core/dev.c:5762
> >  __netif_receive_skb_list net/core/dev.c:5814 [inline]
> >  netif_receive_skb_list_internal+0xa51/0xe30 net/core/dev.c:5905
> >  netif_receive_skb_list+0x55/0x4b0 net/core/dev.c:5957
> >  xdp_recv_frames net/bpf/test_run.c:280 [inline]
> >  xdp_test_run_batch net/bpf/test_run.c:361 [inline]
> >  bpf_test_run_xdp_live+0x1b5e/0x21b0 net/bpf/test_run.c:390
> >  bpf_prog_test_run_xdp+0x805/0x11e0 net/bpf/test_run.c:1318
> >  bpf_prog_test_run+0x2e4/0x360 kernel/bpf/syscall.c:4266
> >  __sys_bpf+0x48d/0x810 kernel/bpf/syscall.c:5671
> >  __do_sys_bpf kernel/bpf/syscall.c:5760 [inline]
> >  __se_sys_bpf kernel/bpf/syscall.c:5758 [inline]
> >  __x64_sys_bpf+0x7c/0x90 kernel/bpf/syscall.c:5758
> >  do_syscall_x64 arch/x86/entry/common.c:52 [inline]
> >  do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
> >  entry_SYSCALL_64_after_hwframe+0x77/0x7f
> > RIP: 0033:0x7f18af25a8e9
> > Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 b8 ff ff ff f7 d8 64 89 01 48
> > RSP: 002b:00007ffee4090af8 EFLAGS: 00000246 ORIG_RAX: 0000000000000141
> > RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f18af25a8e9
> > RDX: 0000000000000048 RSI: 0000000020000600 RDI: 000000000000000a
> > RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
> > R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
> > R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
> >  </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 syzkaller@...glegroups.com.
> >
> > 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
> >
> > If the report is already addressed, let syzbot know by replying with:
> > #syz fix: exact-commit-title
> >
> > If you want syzbot to run the reproducer, reply with:
> > #syz test: git://repo/address.git branch-or-commit-hash
> > If you attach or paste a git patch, syzbot will apply it before testing.
> >
> > If you want to overwrite report's subsystems, reply with:
> > #syz set subsystems: new-subsystem
> > (See the list of subsystem names on the web dashboard)
> >
> > If the report is a duplicate of another one, reply with:
> > #syz dup: exact-subject-of-another-report
>
> @Menglong Dong: could you please have a look? The repro looks
> deterministic, so it should be doable to pin-point the actual, bad
> drop_reason and why/which function is triggering it. My wild guess is
> that an ERRNO is type-casted to drop reason instead of being converted.
>

You are right, I have figured out that the "-EINVAL" is returned
by mistake in fib_validate_source().

Sorry for that, and I'm sending a fix for it.

Thanks!
Menglong Dong

> Cheers,
>
> Paolo
>

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