From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pl1-f177.google.com (mail-pl1-f177.google.com [209.85.214.177]) (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 067F3361965 for ; Wed, 16 Sep 2026 04:11:04 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.214.177 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789531867; cv=none; b=dP6ZhHeUKdf7IaTqsG62gBwrnyWHiaEBaix4/JDofYERrW46c0QtRbcs9N31CJj4/yEBkBSRa6j2mXpoQTSVeI3RwzcybvFcG21QbwG/Iavqi6+WMYkjQQCiLExLrEPiBVpjkOpH3KPYX0bInps1+Hs+IPpReyUxVknxCYiHVS4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789531867; c=relaxed/simple; bh=BG9eS0VX6qiKVgiD2TzOx/munym2UoldfB5y0hqmq+A=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=VnKhdiW/vB2uzOExNSFF+IqpgBqfcHQM7kfsij/J0XPb4Z5USkNqvrFNuKFDD6nkYhZlB9RdDEc9Y1tm2W6vWNUa+7hGV4tXnZKkG0lR4XxkalucRrB3VDY8eN127esUud2cKb5zvsWkH9w62OFxlszgZWTa3wO8jtt3QQ1VCXc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=asu.edu; spf=pass smtp.mailfrom=asu.edu; dkim=pass (2048-bit key) header.d=asu.edu header.i=@asu.edu header.b=MFhDn59u; arc=none smtp.client-ip=209.85.214.177 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=asu.edu Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=asu.edu Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=asu.edu header.i=@asu.edu header.b="MFhDn59u" Received: by mail-pl1-f177.google.com with SMTP id d9443c01a7336-2dd1dcdcf95so14444725ad.1 for ; Tue, 15 Sep 2026 21:11:04 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=asu.edu; s=google; t=1789531864; x=1790136664; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc:subject:date:message-id:reply-to:content-type; bh=nFZ79naFkHGO8T/sa7Ej6UkWwoja78MVIsc91vCgw9k=; b=MFhDn59uJJ3GWyBrovaJkAD7odCGpM8WUhl7YXjWeK4geIA0i6YYp/SSDfVPAdDXMC 07EbKtQzhZlTkzs40a5aiuqCG3qC6wx5K8A51EkYepsMPJillE4ytwWNlXbXO2LtiK/D snlAtiEuyeF7+V94FFJ8ks3tYb6J7DeeVzkA737buGZy2TZuCQd8hrMYxXnQR05xzD+K vQlWV613mm+XqeRXqlMcIkpOjywNUioI3wNpYgnPejjFvsQYpqnDPKkF1sVA/SeAHzBR ZUcm8ynbT0eyIeHUdLFtn63D1as4nVkktdVyRKf17Ym6oFJuuQI3L0AM7Bt1Z4DLQ3HE plsQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20260707; t=1789531864; x=1790136664; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-gg:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to:content-type; bh=nFZ79naFkHGO8T/sa7Ej6UkWwoja78MVIsc91vCgw9k=; b=T5vEdhTUPuaqVXGwlu6iQNvGIp+NygeN4i1770OTDUWHEAeU72PNG1MLiJP4N3InFz Z+LLQS0U14bqJ+d8BQXPkjRuyatSFN3iZLXNBP2N9yLpd6NIZhTaCCahq2y6pCrn9+A/ h3Hze6BJ70XJPTDqppM/pIM2uuvNsfnfAX2Em+sIWTEJsdeST82Dj1B6tH4fZI/5XFLy lE5Tnam1fSRiEYna+Bxd8gGcrqN+Bjm+veOrtSwezne5/hVooj9nGJWD5wacy2jgMGjG fGkEW9cgbbbVEbGdR5M7vvU26/bLhAK77xX8ogqlG5bQe6rX+aiSjJSSC4xt0CyuEp6p wAOw== X-Forwarded-Encrypted: i=1; AKwUvByi4NmB6tAjtq1j7ZP2+eWvtUmgGN1Xk7GGlMbQwpuMVLMc5WP/ras/r3mPf6de3w6Y3sx7rPc=@vger.kernel.org X-Gm-Message-State: AFuF++np5F+uKnGoSZHNeZK83pJmltmglM+++UCteuoB2J0ZPwVi+9Sk 2aMZn228JKds2zt3YZD0bS7ENs2OAy4oLDD2xzpNgsk/rMHov4ZlxVl5hiuQzLhKJQ== X-Gm-Gg: AYBFou23PNc/88LZyUubGWx+43ny3DOITEOqbeb9oRcbtHqpVWqX/NQv8LXB2Cgz3KI 6KZNuGfok8w5g+foXjaT/okVZuwTM+dIiMMlsKIGExJxnWRE7K9gSOd6kmtxAGWhhjNQZT4Akwh dXW44bc1mcL1Z7ZZXrh2tY/VOkqslNhqUYK9e22AYhYQuFIf2ROG09eFQJE7kV/R8/RgzgAlhkF VJwTbjEhyU5TtEQi3Xgqe4iKHllGx0ZPVOtZAkp3Gwru/jAwtzC88gUVVC0PEODyEv9fVMczaRT x3jqT71Ge1iFzP7Ep2XIeqXshO+sZ6CiK5CE+gtIo2GkpBznR1dROM9Rt6wFJ3Pq1L8ViVRjyGm fsmh1ZlXytjAyu9U7jkaYwAXI29aoFGWRKnbpUVO6seYOgmVEqNTJkQeEr7Ifc5ZwvXz+rNqyUJ ZZz1okxo7cOJkz/qhNnwOGGDe0FBNaMekm00/kn+1uswDdaxUMou/LAR7JGUoh0Bc+TPok3ycRk lSXalJSj8xe6As4NwxU9dlrtSerY9B8znATlpVATRgF9eA+ X-Received: by 2002:a17:902:e74f:b0:2d7:1858:1d96 with SMTP id d9443c01a7336-2dd764c14dfmr75730075ad.7.1789531864357; Tue, 15 Sep 2026 21:11:04 -0700 (PDT) Received: from p1.. (209-147-138-4.nat.asu.edu. [209.147.138.4]) by smtp.gmail.com with ESMTPSA id 5a478bee46e88-33bf5af4f0bsm4138749eec.24.2026.09.15.21.11.03 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 15 Sep 2026 21:11:03 -0700 (PDT) From: Xiang Mei To: davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, horms@kernel.org, netdev@vger.kernel.org, bpf@vger.kernel.org Cc: linux-kernel@vger.kernel.org, co+ff13a35f73bb7891@bugs.sh, stable@vger.kernel.org, Xiang Mei Subject: [PATCH net] bpf: lwt: clear stale IP control block after pushing an encap header Date: Tue, 15 Sep 2026 21:11:02 -0700 Message-ID: <20260916041102.1914333-1-xmei5@asu.edu> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit bpf_lwt_push_ip_encap() prepends an encapsulation header and calls skb_reset_network_header(), but leaves the IP control block describing the inner header. Its offsets are relative to the network header, so they now point into the encapsulated packet. On an ingress lwt-bpf encap route a forwarded packet carrying a Record Route option then reaches __ip_options_echo() with a stale opt->rr. It takes the option length from the packet and copies up to 255 bytes into the fixed-size option storage on the __icmp_send() stack. ip_forward_options() writes at a packet-controlled offset for the same reason. Clear the stale state once the outer header is in place, as the tunnel encapsulators do and as seg6_local.c was taught to do in commit f967455fb2a5 ("seg6: reset IP6CB after IPv6 decapsulation") and commit 44930446dde4 ("ipv6: seg6: clear IPv4 control block on IPIP decapsulation"). BUG: KASAN: stack-out-of-bounds in __ip_options_echo (net/ipv4/ip_options.c:96) Write of size 255 at addr ffff8880bee08930 by task exploit/150 Call Trace: __asan_memcpy (mm/kasan/shadow.c:106) __ip_options_echo (net/ipv4/ip_options.c:96) __icmp_send (net/ipv4/icmp.c:949) ip_forward (./include/net/icmp.h:43 net/ipv4/ip_forward.c:176) lwtunnel_input (net/core/lwtunnel.c:465) ip_rcv (net/ipv4/ip_input.c:612) __netif_receive_skb_one_core (net/core/dev.c:6264) process_backlog (net/core/dev.c:6728) __napi_poll (net/core/dev.c:7787) net_rx_action (net/core/dev.c:8007) handle_softirqs (kernel/softirq.c:645) do_softirq.part.0 (kernel/softirq.c:546) __local_bh_enable_ip (kernel/softirq.c:473) __dev_queue_xmit (net/core/dev.c:4961) packet_sendmsg (net/packet/af_packet.c:3143) __sys_sendto (net/socket.c:2281) __x64_sys_sendto (net/socket.c:2288) do_syscall_64 (arch/x86/entry/syscall_64.c:84) entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:121) Cc: stable@vger.kernel.org Fixes: 52f278774e79 ("bpf: implement BPF_LWT_ENCAP_IP mode in bpf_lwt_push_encap") Reported-by: Assisted-by: LLM Signed-off-by: Xiang Mei --- net/core/lwt_bpf.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/net/core/lwt_bpf.c b/net/core/lwt_bpf.c index da49364ec63d..17be476b5717 100644 --- a/net/core/lwt_bpf.c +++ b/net/core/lwt_bpf.c @@ -649,6 +649,18 @@ int bpf_lwt_push_ip_encap(struct sk_buff *skb, void *hdr, u32 len, bool ingress) if (ingress) skb_postpush_rcsum(skb, iph, len); skb_reset_network_header(skb); + if (ipv4) { + memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt)); + } else { + bool l3slave = ipv6_l3mdev_skb(IP6CB(skb)->flags); + int iif = IP6CB(skb)->iif; + + memset(IP6CB(skb), 0, sizeof(*IP6CB(skb))); + IP6CB(skb)->iif = iif; + IP6CB(skb)->nhoff = offsetof(struct ipv6hdr, nexthdr); + if (l3slave) + IP6CB(skb)->flags |= IP6SKB_L3SLAVE; + } if (is_udp_tunnel) { size_t iph_sz = ipv4 ? iph->ihl * 4 : sizeof(struct ipv6hdr); -- 2.43.0