From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-oa1-f79.google.com (mail-oa1-f79.google.com [209.85.160.79]) (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 277CF245008 for ; Tue, 14 Apr 2026 11:58:39 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.160.79 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776167920; cv=none; b=cjkPKzCNdZ6T9HGGCbxPKHLMM3iDzZD41vvaWQkIxoE54vNbv3FVSEmdYT+O7yH/h2ezymL2WBVqREdXQMfcbwhmExQjY9VqPdGEinzz1c0ZSlMU/k/oDmbJEEvLhuZeJr1fWrHhIvLmJIW0sduHzqr1/+ugvNxJd+slY6i2IWI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776167920; c=relaxed/simple; bh=2HaJ7C6Eo6NfwcJIzimyysjHzA/pc/i0mLTwBqWk98U=; h=MIME-Version:Date:Message-ID:Subject:From:To:Content-Type; b=VdwyKHOAbgq6dZ7+WBELdyf1u8ncoiRrO39CDAiiTEbV6C0jppqY4ZVwYowg6xSo26w4dPG0BF0JV35D2V7jRcBaUl0fR8lasrvj7yxMIVOIcw0qH/PY6acjdNG4hVcLA0Git5gqbi5WH1Z54/R/YI6ZM9O2qPgiAsHHm+EC3PI= 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=209.85.160.79 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-oa1-f79.google.com with SMTP id 586e51a60fabf-40a4d2264abso10426691fac.2 for ; Tue, 14 Apr 2026 04:58:39 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1776167918; x=1776772718; h=to:from:subject:message-id:date:mime-version:x-gm-message-state :from:to:cc:subject:date:message-id:reply-to; bh=xCbszGg/pu29m3RS9h0lC44Y5Fgpvv9Jr9lX3YF0Ay4=; b=YzMUizo14JThY6BCJVdxw5BQxRLKedOPBB6X+NobfvdFRygDVXfXjeGISMtSpXZavb 0IRnO74UAW7VfPiRTc99jbvShbYDRNUjBcJCPSu9RprSU2TAhM4TnQeM+2VuErimbpYP 8MnNYlrYKfteKEbXmJfLpDLn8BXGqIjqpd83SDFQ30+DFJxYDCwRdPijddwf3nQwifrW Ce7NoNxNE2sBWw2iC+7/QCL9y12urzFJLHjob0W+xY9oIlUs+YPs307KaK9dWuSQ4+Hj k5JSW+DNfBNAd3oNSoR2Zm1kysBKkwCc4+JyUQIQOcWeTS2biFVt1QqvWtJ1l726vAvF WD6w== X-Gm-Message-State: AOJu0Yx6EeTU1o32DcTnJGsk4rxTyVhtab8Ad7WDSZWycX3dIPPygbSA LnMCp3ZGbYI8sKYonJB+FJ4qD+WFo9E5Gj7Q2p5Dk0aUZfH1481enWfIFuRKdJbrfonOB0I5vjJ UrQXXg/52cPBvrjRsHJGbMX1hz2Nk3zauyEQTrtuiR1PJzrZF4v4b+nmwzzKDZg== Precedence: bulk X-Mailing-List: bridge@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Received: by 2002:a05:6820:2907:b0:682:3fc6:5581 with SMTP id 006d021491bc7-68be5778213mr8828186eaf.7.1776167918128; Tue, 14 Apr 2026 04:58:38 -0700 (PDT) Date: Tue, 14 Apr 2026 04:58:38 -0700 X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <69de2bee.a00a0220.475f0.0041.GAE@google.com> Subject: [syzbot] [bridge?] KASAN: use-after-free Read in qdisc_pkt_len_segs_init From: syzbot To: bridge@lists.linux.dev, davem@davemloft.net, edumazet@google.com, horms@kernel.org, idosch@nvidia.com, kuba@kernel.org, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, pabeni@redhat.com, razor@blackwall.org, syzkaller-bugs@googlegroups.com Content-Type: text/plain; charset="UTF-8" Hello, syzbot found the following issue on: HEAD commit: 17ad4759a082 Merge branch 'wangxun-improvement' git tree: net-next console output: https://syzkaller.appspot.com/x/log.txt?x=1505dcd2580000 kernel config: https://syzkaller.appspot.com/x/.config?x=229411a0a13ccb7d dashboard link: https://syzkaller.appspot.com/bug?extid=83181a31faf9455499c5 compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8 Unfortunately, I don't have any reproducer for this issue yet. Downloadable assets: disk image: https://storage.googleapis.com/syzbot-assets/b67be09d914c/disk-17ad4759.raw.xz vmlinux: https://storage.googleapis.com/syzbot-assets/20a2548795c3/vmlinux-17ad4759.xz kernel image: https://storage.googleapis.com/syzbot-assets/29e723395cef/bzImage-17ad4759.xz IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+83181a31faf9455499c5@syzkaller.appspotmail.com ================================================================== BUG: KASAN: use-after-free in __tcp_hdrlen include/linux/tcp.h:31 [inline] BUG: KASAN: use-after-free in qdisc_pkt_len_segs_init+0x7f8/0xa30 net/core/dev.c:4146 Read of size 2 at addr ffff88815ace2434 by task syz.2.24/6033 CPU: 0 UID: 0 PID: 6033 Comm: syz.2.24 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026 Call Trace: dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120 print_address_description mm/kasan/report.c:378 [inline] print_report+0xba/0x230 mm/kasan/report.c:482 kasan_report+0x117/0x150 mm/kasan/report.c:595 __tcp_hdrlen include/linux/tcp.h:31 [inline] qdisc_pkt_len_segs_init+0x7f8/0xa30 net/core/dev.c:4146 sch_handle_ingress net/core/dev.c:4483 [inline] __netif_receive_skb_core+0x13bd/0x31a0 net/core/dev.c:6065 __netif_receive_skb_list_core+0x24d/0x810 net/core/dev.c:6289 __netif_receive_skb_list net/core/dev.c:6356 [inline] netif_receive_skb_list_internal+0x995/0xcf0 net/core/dev.c:6447 gro_normal_list include/net/gro.h:523 [inline] gro_flush_normal include/net/gro.h:531 [inline] napi_complete_done+0x299/0x730 net/core/dev.c:6815 gro_cell_poll+0x5a9/0x5d0 net/core/gro_cells.c:74 __napi_poll+0xae/0x340 net/core/dev.c:7742 napi_poll net/core/dev.c:7805 [inline] net_rx_action+0x627/0xf70 net/core/dev.c:7962 handle_softirqs+0x22a/0x870 kernel/softirq.c:622 do_softirq+0x76/0xd0 kernel/softirq.c:523 __local_bh_enable_ip+0xf8/0x130 kernel/softirq.c:450 local_bh_enable include/linux/bottom_half.h:33 [inline] tun_rx_batched+0x617/0x790 drivers/net/tun.c:-1 tun_get_user+0x2aeb/0x3ed0 drivers/net/tun.c:1953 tun_chr_write_iter+0x113/0x200 drivers/net/tun.c:1999 new_sync_write fs/read_write.c:595 [inline] vfs_write+0x61d/0xb90 fs/read_write.c:688 ksys_write+0x150/0x270 fs/read_write.c:740 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f177e39c819 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 e8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f177f1e3028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 00007f177e616180 RCX: 00007f177e39c819 RDX: 000000000000fdef RSI: 00002000000002c0 RDI: 0000000000000003 RBP: 00007f177e432c91 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f177e616218 R14: 00007f177e616180 R15: 00007ffee7d40588 The buggy address belongs to the physical page: page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x15ace2 flags: 0x57ff00000000000(node=1|zone=2|lastcpupid=0x7ff) raw: 057ff00000000000 ffffea00056b3888 ffffea00056b3888 0000000000000000 raw: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000000 page dumped because: kasan: bad access detected page_owner info is not present (never set?) Memory state around the buggy address: ffff88815ace2300: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ffff88815ace2380: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff >ffff88815ace2400: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ^ ffff88815ace2480: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ffff88815ace2500: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ================================================================== --- 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