From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-oo1-f69.google.com (mail-oo1-f69.google.com [209.85.161.69]) (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 EB52A2D8760 for ; Mon, 9 Mar 2026 12:13:43 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.161.69 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773058425; cv=none; b=q0qDYQE1S/YfhMZbqil99IwnsKgl+yX+aaJbhd7ef+LGypkRkFyRIhzwe1fe30cGkivelFt6s2hcZy9ku1ILEgHYKjp8hpAq1PZugjzPREWOOwJ46vucq7sOZ+TBdIh2xn3ECgKz4FWeMMBddERQZEBWJt+VafHSKt+GDPZneqg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773058425; c=relaxed/simple; bh=PSve9+OZ0uIyrVvrL+k8kYaMyjyZV5bNHKf4r6mYMjg=; h=MIME-Version:Date:Message-ID:Subject:From:To:Content-Type; b=sknKlnhYReEo90nukrGO1bv0QJWETtsxz9vTvb1G1OYGD2UmOBEmoflXq87n+tR2fDK9+Owa9ZvB+s6i+gMg/au9DRR5Kr33nxvpJa7u0g8BYcexdhyQKQJTnO3+0RFVcBrbktt33HvDGvS3cxjyliWfh7KOw3EegpgcGmup6Fk= 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=209.85.161.69 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-oo1-f69.google.com with SMTP id 006d021491bc7-672c40f3873so198184909eaf.2 for ; Mon, 09 Mar 2026 05:13:43 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1773058423; x=1773663223; h=to:from:subject:message-id:date:mime-version:x-gm-message-state :from:to:cc:subject:date:message-id:reply-to; bh=TqsjNRI5k7LetfZtjLKtuc4uxl4nwGBY89RPRBdE1pE=; b=TgWCZL8qK+1iS2//oB+GoQ4Oxho5az9aOYeFhKDI7y+b4gsa4bN3TE7fwGjCSiV6rs DdI5/rEnmT/Hn32LY9VHOcepjmomHWp5ldXoDp/DBQwxpCUi7VP66zLj5dtmySAAQexE epZZW0wscv4boki5asJE5WxNa2rSjrJwWZDfiSI6PYYDNyKixknxYzAsqQWUKd5GSdY9 SinMns4sZHeGAo7lmFg+73xR/MpzjR/yFRa8/eOXKbcUJtDnVNVt9WaECYbKG1znK0To zNd5Er+l3gkCN6ruwI4GE3z9t1YnUCpPybVshoSZ5LZLYob1tH7pNCMmlV4SlPufZGEk Adgg== X-Forwarded-Encrypted: i=1; AJvYcCWGTsJtFH7PfbQ8vkUBh5Kak95qweIYsWQq1GaUR9J5dzgFkpH7vUf7rqSmEquVBphXKmOCIsA=@vger.kernel.org X-Gm-Message-State: AOJu0YyZbrbEu6Xhrevmdd5QOY9oVXslud6pb219PqhCzPIWAMLySolu uLYgfNiucowAHm8obZiW6CxNUd7RJ3qhnJnawhldGS22MnS5fA6oYUGvTtUBRz26bct99h9gX2l P/rPoCFnuDIvd3DFKLeU1cfl2M57VvqYB8/rDAoq9Y5t2fongLWZsmhtIlRs= Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Received: by 2002:a05:6820:c92:b0:67b:adbe:c3cb with SMTP id 006d021491bc7-67badbec51bmr3811015eaf.56.1773058422821; Mon, 09 Mar 2026 05:13:42 -0700 (PDT) Date: Mon, 09 Mar 2026 05:13:42 -0700 X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <69aeb976.a70a0220.52840.0015.GAE@google.com> Subject: [syzbot] [net?] KASAN: null-ptr-deref Write in send_to_lecd From: syzbot To: davem@davemloft.net, edumazet@google.com, horms@kernel.org, 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: 014441d1e4b2 Merge tag 'i2c-for-7.0-rc3' of git://git.kern.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=11230d52580000 kernel config: https://syzkaller.appspot.com/x/.config?x=976ba5a93c4add9e dashboard link: https://syzkaller.appspot.com/bug?extid=e1d2b89a60c8bb9a7f33 compiler: gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44 Unfortunately, I don't have any reproducer for this issue yet. Downloadable assets: disk image: https://storage.googleapis.com/syzbot-assets/c6996386f74c/disk-014441d1.raw.xz vmlinux: https://storage.googleapis.com/syzbot-assets/50d7e742ec37/vmlinux-014441d1.xz kernel image: https://storage.googleapis.com/syzbot-assets/8b042e15289c/bzImage-014441d1.xz IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+e1d2b89a60c8bb9a7f33@syzkaller.appspotmail.com ================================================================== BUG: KASAN: null-ptr-deref in instrument_atomic_read_write include/linux/instrumented.h:112 [inline] BUG: KASAN: null-ptr-deref in atomic_add include/linux/atomic/atomic-instrumented.h:104 [inline] BUG: KASAN: null-ptr-deref in atm_force_charge include/linux/atmdev.h:261 [inline] BUG: KASAN: null-ptr-deref in send_to_lecd+0x2ef/0x5e0 net/atm/lec.c:535 Write of size 4 at addr 0000000000000140 by task dhcpcd/28797 CPU: 1 UID: 101 PID: 28797 Comm: dhcpcd Tainted: G L syzkaller #0 PREEMPT(full) Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026 Call Trace: __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120 kasan_report+0xdf/0x1e0 mm/kasan/report.c:595 check_region_inline mm/kasan/generic.c:186 [inline] kasan_check_range+0x10f/0x1e0 mm/kasan/generic.c:200 instrument_atomic_read_write include/linux/instrumented.h:112 [inline] atomic_add include/linux/atomic/atomic-instrumented.h:104 [inline] atm_force_charge include/linux/atmdev.h:261 [inline] send_to_lecd+0x2ef/0x5e0 net/atm/lec.c:535 lec_arp_resolve net/atm/lec.c:1791 [inline] lec_start_xmit+0x1252/0x2070 net/atm/lec.c:285 __netdev_start_xmit include/linux/netdevice.h:5292 [inline] netdev_start_xmit include/linux/netdevice.h:5301 [inline] xmit_one net/core/dev.c:3871 [inline] dev_hard_start_xmit+0x121/0x7d0 net/core/dev.c:3887 sch_direct_xmit+0x1b2/0xc60 net/sched/sch_generic.c:347 qdisc_restart net/sched/sch_generic.c:412 [inline] __qdisc_run+0x52d/0x1b10 net/sched/sch_generic.c:420 qdisc_run include/net/pkt_sched.h:120 [inline] qdisc_run include/net/pkt_sched.h:117 [inline] __dev_xmit_skb net/core/dev.c:4196 [inline] __dev_queue_xmit+0x196d/0x4800 net/core/dev.c:4802 dev_queue_xmit include/linux/netdevice.h:3384 [inline] packet_xmit+0x243/0x310 net/packet/af_packet.c:275 packet_snd net/packet/af_packet.c:3076 [inline] packet_sendmsg+0x32f4/0x53c0 net/packet/af_packet.c:3108 sock_sendmsg_nosec net/socket.c:727 [inline] __sock_sendmsg net/socket.c:742 [inline] sock_write_iter+0x524/0x5a0 net/socket.c:1195 do_iter_readv_writev+0x6ee/0x920 fs/read_write.c:829 vfs_writev+0x360/0xe10 fs/read_write.c:1059 do_writev+0x28a/0x340 fs/read_write.c:1105 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x106/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f53f6e3c407 Code: 48 89 fa 4c 89 df e8 38 aa 00 00 8b 93 08 03 00 00 59 5e 48 83 f8 fc 74 1a 5b c3 0f 1f 84 00 00 00 00 00 48 8b 44 24 10 0f 05 <5b> c3 0f 1f 80 00 00 00 00 83 e2 39 83 fa 08 75 de e8 23 ff ff ff RSP: 002b:00007fff9cf80170 EFLAGS: 00000202 ORIG_RAX: 0000000000000014 RAX: ffffffffffffffda RBX: 00007f53f6db2780 RCX: 00007f53f6e3c407 RDX: 0000000000000002 RSI: 00007fff9cf801d0 RDI: 0000000000000003 RBP: 0000000000000188 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000202 R12: 00007fff9cf80210 R13: 0000562512791790 R14: 00007fff9cf80260 R15: 00007fff9cf90430 ================================================================== --- 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