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-0700 (PDT) Date: Wed, 12 Aug 2026 05:52:38 -0700 In-Reply-To: <6a6f9105.1aa927e4.17d4bf.001b.GAE@google.com> X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <6a7c6c96.d5f0ebe7.22d851.000d.GAE@google.com> Subject: Forwarded: Re: [syzbot] [net?] WARNING in ipgre_xmit (2) From: syzbot To: linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable For archival purposes, forwarding an incoming command email to linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com. *** Subject: Re: [syzbot] [net?] WARNING in ipgre_xmit (2) Author: kerneljasonxing@gmail.com On Wed, Aug 5, 2026 at 1:05=E2=80=AFAM syzbot wrote: > > syzbot has found a reproducer for the following issue on: > > HEAD commit: 848acc8ffe1b Merge tag 'fsverity-for-linus' of git://git.= k.. > git tree: upstream > console+strace: https://syzkaller.appspot.com/x/log.txt?x=3D178fb64958000= 0 > kernel config: https://syzkaller.appspot.com/x/.config?x=3D4e38b15c29e6a= 1d9 > dashboard link: https://syzkaller.appspot.com/bug?extid=3Df16c1b285c9f639= 94eec > compiler: Debian clang version 22.1.8 (++20260613092233+e80beda6e25= 5-1~exp1~20260613092250.77), Debian LLD 22.1.8 > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=3D1617be32580= 000 > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=3D11d113b958000= 0 > > Downloadable assets: > disk image: https://storage.googleapis.com/syzbot-assets/4949138dcfef/dis= k-848acc8f.raw.xz > vmlinux: https://storage.googleapis.com/syzbot-assets/31cc6fbe5b8a/vmlinu= x-848acc8f.xz > kernel image: https://storage.googleapis.com/syzbot-assets/433919ca6520/b= zImage-848acc8f.xz > > IMPORTANT: if you fix the issue, please add the following tag to the comm= it: > Reported-by: syzbot+f16c1b285c9f63994eec@syzkaller.appspotmail.com > > ------------[ cut here ]------------ > len > ((int)(~0U >> 1)) > WARNING: ./include/linux/skbuff.h:2864 at pskb_may_pull_reason include/li= nux/skbuff.h:2864 [inline], CPU#1: syz-executor147/5638 > WARNING: ./include/linux/skbuff.h:2864 at pskb_network_may_pull_reason in= clude/linux/skbuff.h:3265 [inline], CPU#1: syz-executor147/5638 > WARNING: ./include/linux/skbuff.h:2864 at pskb_inet_may_pull_reason inclu= de/net/ip_tunnels.h:481 [inline], CPU#1: syz-executor147/5638 > WARNING: ./include/linux/skbuff.h:2864 at pskb_inet_may_pull include/net/= ip_tunnels.h:486 [inline], CPU#1: syz-executor147/5638 > WARNING: ./include/linux/skbuff.h:2864 at ipgre_xmit+0x958/0xcd0 net/ipv4= /ip_gre.c:658, CPU#1: syz-executor147/5638 > Modules linked in: > CPU: 1 UID: 0 PID: 5638 Comm: syz-executor147 Not tainted syzkaller #0 PR= EEMPT(full) > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS G= oogle 07/24/2026 > RIP: 0010:pskb_may_pull_reason include/linux/skbuff.h:2864 [inline] > RIP: 0010:pskb_network_may_pull_reason include/linux/skbuff.h:3265 [inlin= e] > RIP: 0010:pskb_inet_may_pull_reason include/net/ip_tunnels.h:481 [inline] > RIP: 0010:pskb_inet_may_pull include/net/ip_tunnels.h:486 [inline] > RIP: 0010:ipgre_xmit+0x958/0xcd0 net/ipv4/ip_gre.c:658 > Code: 48 3b 84 24 80 00 00 00 0f 85 3b 01 00 00 31 c0 48 8d 65 d8 5b 41 5= c 41 5d 41 5e 41 5f 5d e9 3f 1a 78 01 cc e8 09 f5 6a f7 90 <0f> 0b 90 e9 08= f8 ff ff 44 89 ff 44 89 e6 e8 b5 f6 6a f7 45 39 e7 > RSP: 0018:ffffc900039af5e0 EFLAGS: 00010293 > RAX: ffffffff8a5c1d67 RBX: 0000000000000000 RCX: ffff888079535d00 > RDX: 0000000000000000 RSI: 00000000ffffff40 RDI: 0000000000000000 > RBP: ffffc900039af6b0 R08: ffff888079535d00 R09: 0000000000000002 > R10: 0000000000004888 R11: ffffffff8a5c1410 R12: ffff88807ecbc000 > R13: dffffc0000000000 R14: ffff88807b7f2780 R15: 00000000ffffff40 > FS: 0000555590a0a400(0000) GS:ffff88812504b000(0000) knlGS:0000000000000= 000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 000055704428ded0 CR3: 00000000788f2000 CR4: 00000000003526f0 > Call Trace: > > __netdev_start_xmit include/linux/netdevice.h:5400 [inline] > netdev_start_xmit include/linux/netdevice.h:5409 [inline] > __dev_direct_xmit+0x4b6/0x730 net/core/dev.c:4942 > __xsk_generic_xmit net/xdp/xsk.c:1253 [inline] > xsk_generic_xmit+0x2759/0x47b0 net/xdp/xsk.c:1309 > __xsk_sendmsg net/xdp/xsk.c:1363 [inline] > xsk_sendmsg+0x482/0x810 net/xdp/xsk.c:1373 > sock_sendmsg_nosec+0x13a/0x180 net/socket.c:775 > __sock_sendmsg net/socket.c:790 [inline] > ____sys_sendmsg+0x54e/0x850 net/socket.c:2684 > ___sys_sendmsg+0x2a5/0x360 net/socket.c:2738 > __sys_sendmsg net/socket.c:2770 [inline] > __do_sys_sendmsg net/socket.c:2775 [inline] > __se_sys_sendmsg net/socket.c:2773 [inline] > __x64_sys_sendmsg+0x1b1/0x290 net/socket.c:2773 > do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] > do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94 > entry_SYSCALL_64_after_hwframe+0x77/0x7f > RIP: 0033:0x7fc137b1b409 > Code: c0 79 93 eb d5 48 8d 7c 1d 00 eb 99 0f 1f 44 00 00 48 89 f8 48 89 f= 7 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 d8 ff ff ff f7 d8 64 89 01 48 > RSP: 002b:00007fffc9ef46d8 EFLAGS: 00000246 ORIG_RAX: 000000000000002e > RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fc137b1b409 > RDX: 0000000000000040 RSI: 0000200000000700 RDI: 0000000000000003 > RBP: 0000000000000000 R08: 0000000080000000 R09: 0000000080000000 > R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 > R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000003 > > > > --- > 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. > #syz test diff --git a/net/xdp/xsk.c b/net/xdp/xsk.c index 7855ee09c4b6..aa0d397d569e 100644 --- a/net/xdp/xsk.c +++ b/net/xdp/xsk.c @@ -1028,6 +1028,7 @@ static struct sk_buff *xsk_build_skb_zerocopy(struct xdp_sock *xs, return ERR_PTR(err); skb_reserve(skb, hr); + skb_reset_network_header(skb); if (desc->options & XDP_TX_METADATA) { err =3D xsk_skb_metadata(skb, buffer, desc, pool, hr); if (unlikely(err)) { @@ -1112,6 +1113,7 @@ static struct sk_buff *xsk_build_skb(struct xdp_sock = *xs, skb_reserve(skb, hr); skb_put(skb, len); + skb_reset_network_header(skb); err =3D skb_store_bits(skb, 0, buffer, len); if (unlikely(err)) --=20 2.43.5