From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-oi2-f0.google.com (mail-oi2-f0.google.com [74.125.231.192]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id BEF593812EC for ; Sun, 23 Aug 2026 18:19:46 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=74.125.231.192 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787509189; cv=none; b=UUHA7if60OL135n1GFi31lFJeYQ5D89E6wPtyCVkv0O2hZayT/DliAK3AY8ID0l0572FVXR643HQ0WTG8Blzm5QVQFRG6OCYVhQclyUIqL62iYvVcFxuflspXpUuzpCJm9+qfSQAw66O86GD+ce9/TB95nQXwaphKgggrU/x+sc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787509189; c=relaxed/simple; bh=jf5imuzUDrGWQW0D30IbauTDaI7H0/bOyFEg9tdKObk=; h=MIME-Version:Date:Message-ID:Subject:From:To:Content-Type; b=fVBbTLlrapUjx3x4f9Vybo6KuLFTQ6cvQAASSfHX6+wnDi5KLua9aTbu51r119S1g8E6AwM94TzrZZPXdQbU3RMBuuEqRLQ0fq2jM2P3cNxCthPSLylMQMb6r0Bu9Y/iFFmPV6S4Xl4TBuXuvLfqgWFFVTW71tfZL1k4kIB53FY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=fail (p=none dis=none) header.from=syzkaller.appspotmail.com; spf=pass smtp.mailfrom=M3KW2WVRGUFZ5GODRSRYTGD7.apphosting.bounces.google.com; arc=none smtp.client-ip=74.125.231.192 Authentication-Results: smtp.subspace.kernel.org; dmarc=fail (p=none dis=none) header.from=syzkaller.appspotmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=M3KW2WVRGUFZ5GODRSRYTGD7.apphosting.bounces.google.com Received: by mail-oi2-f0.google.com with SMTP id 5614622812f47-4a41b6fb855so1091234b6e.1 for ; Sun, 23 Aug 2026 11:19:46 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1787509185; x=1788113985; h=content-type:to:from:subject:message-id:date:mime-version :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to :content-type; bh=qGloX+V1+57Pi8MeXi194PQoze6c1QdyTbNQsGRbY68=; b=a52AdhEZMnf/tGJHOm+A/2WNmbYMrLFqhszYIcp+n4x4f+kyxjT/6J0NYqszP0gkoH 5knwAJkkpGMN72aDUi+wM5D2G3Wv+6bSZq7+5NJJJEuST4ePrDEyAuo5tPuXCZH5nSv1 XXXpWefV4nXts5FipJUcqBsPgeXaQ8FFaA7JMSlhbRR4qmOFOHape2Ma02Gkserq4ItE vS17DdhQWg7+DOUzz7keTCG54yuS97nnkuCVTvgCre6JXhRfc2ngFotGDaygr/ynDF1s LeJMgSYzOZRJALQsNxRFYiFblUFTKTT4G9WXyI/Nu01J+vhZWFj7OXR+UMkou8IPcBYp gUpA== X-Forwarded-Encrypted: i=1; AHgh+RpPtijMurAISsiWEhIeFjNwGLw6fRNHCgvdYEMylLjZM5t+GgV2X+G1Z8E5gFJkk9FsJ9zr7eyat7Vyp8Y=@vger.kernel.org X-Gm-Message-State: AFuF++lK6vwkbKEdqE/kcE8dP7+GXOVB+I3CkNsxLDQ0E2TbGXfahRqE J5gW8cdi2jGc2pq97eeI2nMFXAHu6GYfP48kKKKWfaHhLaYVJJQwcgAbd2vvJ3uVSpZldrDDItb fKkwFv17oAhbEncV8RbrwvapD3TzhRz4973JafAJ04XajFD5+sZrTi8XgKXk= Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Received: by 2002:a05:6808:c3f3:b0:4a3:fb6c:9adf with SMTP id 5614622812f47-4b2ef3e6390mr20588939b6e.12.1787509184819; Sun, 23 Aug 2026 11:19:44 -0700 (PDT) Date: Sun, 23 Aug 2026 11:19:44 -0700 X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <6a8b39c0.dbb3a75c.13dd47.0051.GAE@google.com> Subject: [syzbot] [net?] WARNING in tcf_skbmod_act From: syzbot To: davem@davemloft.net, edumazet@google.com, horms@kernel.org, jhs@mojatatu.com, jiri@resnulli.us, kuba@kernel.org, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, pabeni@redhat.com, syzkaller-bugs@googlegroups.com Content-Type: text/plain; charset="UTF-8" Hello, syzbot found the following issue on: HEAD commit: 66fb95a52111 Merge tag 'caps-pr-20260820' of git://git.ker.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=135f6179580000 kernel config: https://syzkaller.appspot.com/x/.config?x=a70bec3546180b6 dashboard link: https://syzkaller.appspot.com/bug?extid=1d56f14f95c0480cfdc9 compiler: Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8 Unfortunately, I don't have any reproducer for this issue yet. Downloadable assets: disk image: https://storage.googleapis.com/syzbot-assets/6da0d1c4d90d/disk-66fb95a5.raw.xz vmlinux: https://storage.googleapis.com/syzbot-assets/34b5360f76fd/vmlinux-66fb95a5.xz kernel image: https://storage.googleapis.com/syzbot-assets/bea190471e9f/bzImage-66fb95a5.xz IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+1d56f14f95c0480cfdc9@syzkaller.appspotmail.com ------------[ cut here ]------------ !skb_transport_header_was_set(skb) WARNING: ./include/linux/skbuff.h:3243 at skb_network_header_len include/linux/skbuff.h:3243 [inline], CPU#0: syz.0.2516/14949 WARNING: ./include/linux/skbuff.h:3243 at tcf_skbmod_act+0xfe8/0x1810 net/sched/act_skbmod.c:55, CPU#0: syz.0.2516/14949 Modules linked in: CPU: 0 UID: 0 PID: 14949 Comm: syz.0.2516 Tainted: G L syzkaller #0 PREEMPT(full) Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026 RIP: 0010:skb_network_header_len include/linux/skbuff.h:3243 [inline] RIP: 0010:tcf_skbmod_act+0xfe8/0x1810 net/sched/act_skbmod.c:55 Code: 48 c1 e8 03 42 80 3c 20 00 74 08 48 89 df e8 6f 05 60 f8 48 8b 03 65 ff 40 10 b8 02 00 00 00 e9 66 ff ff ff e8 99 5b f0 f7 90 <0f> 0b 90 e9 a0 f5 ff ff e8 8b 5b f0 f7 90 0f 0b 90 e9 49 f6 ff ff RSP: 0018:ffffc90006c571c8 EFLAGS: 00010293 RAX: ffffffff89d6cdf7 RBX: 1ffff1100fa67d56 RCX: ffff888029678000 RDX: 0000000000000000 RSI: 000000000000ffff RDI: 000000000000ffff RBP: 0000000000000010 R08: ffff888029678000 R09: 0000000000000002 R10: 000000000000dd86 R11: 0000000000000000 R12: 000000000000ffff R13: ffff88807d33eab6 R14: 000000000000000e R15: ffff88807d33eaba FS: 00007fecc9f156c0(0000) GS:ffff888124cfd000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fecc9f14ff8 CR3: 00000000265a6000 CR4: 00000000003526f0 Call Trace: tc_act include/net/tc_wrapper.h:131 [inline] tcf_action_exec+0x185/0x8d0 net/sched/act_api.c:1150 tcf_exts_exec include/net/pkt_cls.h:361 [inline] basic_classify+0x1b2/0x2d0 net/sched/cls_basic.c:54 tc_classify include/net/tc_wrapper.h:198 [inline] __tcf_classify net/sched/cls_api.c:1779 [inline] tcf_classify+0x43d/0x1160 net/sched/cls_api.c:1875 tc_run+0x42d/0x750 net/core/dev.c:4463 sch_handle_ingress net/core/dev.c:4538 [inline] __netif_receive_skb_core+0x1443/0x30c0 net/core/dev.c:6115 __netif_receive_skb_one_core net/core/dev.c:6262 [inline] __netif_receive_skb net/core/dev.c:6377 [inline] netif_receive_skb_internal net/core/dev.c:6463 [inline] netif_receive_skb+0x1fe/0xbf0 net/core/dev.c:6522 tun_rx_batched+0x1de/0x790 drivers/net/tun.c:1571 tun_get_user+0x2be0/0x44d0 drivers/net/tun.c:2045 tun_chr_write_iter+0x113/0x200 drivers/net/tun.c:2091 new_sync_write fs/read_write.c:595 [inline] vfs_write+0x612/0xba0 fs/read_write.c:687 ksys_write+0x150/0x270 fs/read_write.c:739 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline] do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fecc8f5e90e Code: 08 0f 85 a5 a8 ff ff 49 89 fb 48 89 f0 48 89 d7 48 89 ce 4c 89 c2 4d 89 ca 4c 8b 44 24 08 4c 8b 4c 24 10 4c 89 5c 24 08 0f 05 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 80 00 00 00 00 48 83 ec 08 RSP: 002b:00007fecc9f14fb8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 00007fecc9f156c0 RCX: 00007fecc8f5e90e RDX: 0000000000000097 RSI: 0000200000000080 RDI: 00000000000000c8 RBP: 00007fecc9035024 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fecc9226038 R14: 00007fecc9225fa0 R15: 00007fecc934fa48 --- 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