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From: Kuniyuki Iwashima <kuniyu@amazon.com>
To: <edumazet@google.com>
CC: <davem@davemloft.net>, <dsahern@kernel.org>, <kuba@kernel.org>,
	<kuniyu@amazon.com>, <linux-kernel@vger.kernel.org>,
	<netdev@vger.kernel.org>, <pabeni@redhat.com>,
	<syzbot+c298c9f0e46a3c86332b@syzkaller.appspotmail.com>,
	<syzkaller-bugs@googlegroups.com>
Subject: Re: [syzbot] [net?] WARNING in gre_tap_xmit (2)
Date: Fri, 19 Apr 2024 10:22:50 -0700
Message-ID: <20240419172250.83685-1-kuniyu@amazon.com>
In-Reply-To: <CANn89iKNcQOcRX1vGVXFBXn1Z2axGS+hWuhxKOAaq8BCo4W0bw@mail.gmail.com>
References: <CANn89iKNcQOcRX1vGVXFBXn1Z2axGS+hWuhxKOAaq8BCo4W0bw@mail.gmail.com>
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From: Eric Dumazet <edumazet@google.com>
Date: Fri, 19 Apr 2024 12:10:42 +0200
> On Fri, Apr 19, 2024 at 11:39 AM syzbot
> <syzbot+c298c9f0e46a3c86332b@syzkaller.appspotmail.com> wrote:
> >
> > Hello,
> >
> > syzbot found the following issue on:
> >
> > HEAD commit:    443574b03387 riscv, bpf: Fix kfunc parameters incompatibil..
> > git tree:       bpf
> > console output: https://syzkaller.appspot.com/x/log.txt?x=165886c3180000
> > kernel config:  https://syzkaller.appspot.com/x/.config?x=6fb1be60a193d440
> > dashboard link: https://syzkaller.appspot.com/bug?extid=c298c9f0e46a3c86332b
> > compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
> >
> > Unfortunately, I don't have any reproducer for this issue yet.
> >
> > Downloadable assets:
> > disk image: https://storage.googleapis.com/syzbot-assets/3f355021a085/disk-443574b0.raw.xz
> > vmlinux: https://storage.googleapis.com/syzbot-assets/44cf4de7472a/vmlinux-443574b0.xz
> > kernel image: https://storage.googleapis.com/syzbot-assets/a99a36c7ad65/bzImage-443574b0.xz
> >
> > IMPORTANT: if you fix the issue, please add the following tag to the commit:
> > Reported-by: syzbot+c298c9f0e46a3c86332b@syzkaller.appspotmail.com
> >
> > ------------[ cut here ]------------
> > WARNING: CPU: 0 PID: 13407 at include/linux/skbuff.h:2740 pskb_may_pull_reason include/linux/skbuff.h:2740 [inline]
> > WARNING: CPU: 0 PID: 13407 at include/linux/skbuff.h:2740 pskb_may_pull include/linux/skbuff.h:2756 [inline]
> > WARNING: CPU: 0 PID: 13407 at include/linux/skbuff.h:2740 pskb_network_may_pull include/linux/skbuff.h:3077 [inline]
> > WARNING: CPU: 0 PID: 13407 at include/linux/skbuff.h:2740 pskb_inet_may_pull include/net/ip_tunnels.h:361 [inline]
> > WARNING: CPU: 0 PID: 13407 at include/linux/skbuff.h:2740 gre_tap_xmit+0x4ff/0x6e0 net/ipv4/ip_gre.c:734
> > Modules linked in:
> > CPU: 0 PID: 13407 Comm: syz-executor.1 Not tainted 6.8.0-syzkaller-05236-g443574b03387 #0
> > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
> > RIP: 0010:pskb_may_pull_reason include/linux/skbuff.h:2740 [inline]
> > RIP: 0010:pskb_may_pull include/linux/skbuff.h:2756 [inline]
> > RIP: 0010:pskb_network_may_pull include/linux/skbuff.h:3077 [inline]
> > RIP: 0010:pskb_inet_may_pull include/net/ip_tunnels.h:361 [inline]
> > RIP: 0010:gre_tap_xmit+0x4ff/0x6e0 net/ipv4/ip_gre.c:734
> > Code: 00 4c 89 ef 48 89 ee 48 89 da e8 7c 8f fb ff 31 c0 48 83 c4 38 5b 41 5c 41 5d 41 5e 41 5f 5d c3 cc cc cc cc e8 62 55 9d f7 90 <0f> 0b 90 e9 09 fc ff ff 44 89 e7 89 ee e8 0f 57 9d f7 41 39 ec 0f
> > RSP: 0018:ffffc90004b66e00 EFLAGS: 00010287
> > RAX: ffffffff89f79b0e RBX: ffff888061667718 RCX: 0000000000040000
> > RDX: ffffc9000c375000 RSI: 00000000000124e0 RDI: 00000000000124e1
> > RBP: 00000000ffffffb6 R08: ffffffff89f79712 R09: 1ffffffff1f0d5cd
> > R10: dffffc0000000000 R11: ffffffff89f79610 R12: 0000000000000000
> > R13: ffff888061667640 R14: ffff888062b64000 R15: dffffc0000000000
> > FS:  00007f08d29ff6c0(0000) GS:ffff8880b9400000(0000) knlGS:0000000000000000
> > CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> > CR2: 0000000020010000 CR3: 0000000061678000 CR4: 00000000003506f0
> > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> > DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
> > Call Trace:
> >  <TASK>
> >  __netdev_start_xmit include/linux/netdevice.h:4903 [inline]
> >  netdev_start_xmit include/linux/netdevice.h:4917 [inline]
> >  xmit_one net/core/dev.c:3531 [inline]
> >  dev_hard_start_xmit+0x26a/0x790 net/core/dev.c:3547
> >  sch_direct_xmit+0x2b6/0x5f0 net/sched/sch_generic.c:343
> >  __dev_xmit_skb net/core/dev.c:3760 [inline]
> >  __dev_queue_xmit+0x1912/0x3b10 net/core/dev.c:4301
> >  bond_start_xmit+0x1389/0x1c40 drivers/net/bonding/bond_main.c:5469
> >  __netdev_start_xmit include/linux/netdevice.h:4903 [inline]
> >  netdev_start_xmit include/linux/netdevice.h:4917 [inline]
> >  xmit_one net/core/dev.c:3531 [inline]
> >  dev_hard_start_xmit+0x26a/0x790 net/core/dev.c:3547
> >  __dev_queue_xmit+0x19f4/0x3b10 net/core/dev.c:4335
> >  packet_snd net/packet/af_packet.c:3083 [inline]
> >  packet_sendmsg+0x4932/0x63d0 net/packet/af_packet.c:3115
> >  sock_sendmsg_nosec net/socket.c:730 [inline]
> >  __sock_sendmsg+0x221/0x270 net/socket.c:745
> >  ____sys_sendmsg+0x525/0x7d0 net/socket.c:2584
> >  ___sys_sendmsg net/socket.c:2638 [inline]
> >  __sys_sendmsg+0x2b0/0x3a0 net/socket.c:2667
> >  do_syscall_64+0xfb/0x240
> >  entry_SYSCALL_64_after_hwframe+0x6d/0x75
> > RIP: 0033:0x7f08d2e7dea9
> > Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 e1 20 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 b0 ff ff ff f7 d8 64 89 01 48
> > RSP: 002b:00007f08d29ff0c8 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
> > RAX: ffffffffffffffda RBX: 00007f08d2fabf80 RCX: 00007f08d2e7dea9
> > RDX: 00000000200400c4 RSI: 0000000020000180 RDI: 0000000000000006
> > RBP: 00007f08d2eca4a4 R08: 0000000000000000 R09: 0000000000000000
> > R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
> > R13: 000000000000000b R14: 00007f08d2fabf80 R15: 00007ffcba0da4f8
> >  </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@googlegroups.com.
> >
> > syzbot will keep track of this issue. See:
> > https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
> >
> > If the report is already addressed, let syzbot know by replying with:
> > #syz fix: exact-commit-title
> >
> > 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
> >
> > If you want to undo deduplication, reply with:
> > #syz undup
> 
> Kuniyuki , this is another manifestation of NSH bug, thanks !

Thanks, will take a look at the repro !

I got a similar v6 gre splat yesterday with no repro, but
this v4 one has, nice :)

Call trace:
 pskb_may_pull_reason include/linux/skbuff.h:2740 [inline]
 pskb_may_pull include/linux/skbuff.h:2756 [inline]
 pskb_network_may_pull include/linux/skbuff.h:3077 [inline]
 pskb_inet_may_pull include/net/ip_tunnels.h:361 [inline]
 ip6gre_tunnel_xmit+0xea0/0x13b8 net/ipv6/ip6_gre.c:901