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([159.65.159.133]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-359833ef647sm2220754a91.3.2026.03.01.02.57.20 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 01 Mar 2026 02:57:23 -0800 (PST) From: Roshan Kumar To: steffen.klassert@secunet.com, herbert@gondor.apana.org.au, davem@davemloft.net Cc: chopps@labn.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, horms@kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org, Roshan Kumar Subject: [PATCH] xfrm: iptfs: validate inner IPv4 header length in IPTFS payload Date: Sun, 1 Mar 2026 10:56:38 +0000 Message-ID: <20260301105638.11479-1-roshaen09@gmail.com> X-Mailer: git-send-email 2.48.1 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Add validation of the inner IPv4 packet tot_len and ihl fields parsed from decrypted IPTFS payloads in __input_process_payload(). A crafted ESP packet containing an inner IPv4 header with tot_len=3D0 causes an infinite loop: iplen=3D0 leads to capturelen=3Dmin(0, remaining)=3D0, so the data offset never advances and the while(data < tail) loop never terminates, spinning forever in softirq context. Reject inner IPv4 packets where tot_len < ihl*4 or ihl*4 < sizeof(struct iphdr), which catches both the tot_len=3D0 case and malformed ihl values. The normal IP stack performs this validation in ip_rcv_core(), but IPTFS extracts and processes inner packets before they reach that layer. Reported-by: Roshan Kumar Fixes: 6c82d2433671 ("xfrm: iptfs: add basic receive packet (tunnel egress)= handling") Cc: stable@vger.kernel.org Signed-off-by: Roshan Kumar --- net/xfrm/xfrm_iptfs.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/net/xfrm/xfrm_iptfs.c b/net/xfrm/xfrm_iptfs.c index 050a82101ca5..4cd0747367bd 100644 --- a/net/xfrm/xfrm_iptfs.c +++ b/net/xfrm/xfrm_iptfs.c @@ -991,6 +991,11 @@ static bool __input_process_payload(struct xfrm_state = *x, u32 data, =20 iplen =3D be16_to_cpu(iph->tot_len); iphlen =3D iph->ihl << 2; + if (iplen < iphlen || iphlen < sizeof(*iph)) { + XFRM_INC_STATS(net, + LINUX_MIB_XFRMINHDRERROR); + goto done; + } protocol =3D cpu_to_be16(ETH_P_IP); XFRM_MODE_SKB_CB(skbseq->root_skb)->tos =3D iph->tos; } else if (iph->version =3D=3D 0x6) { --=20 2.48.1