From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pz2-f43.google.com (mail-pz2-f43.google.com [74.125.228.43]) (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 0C2081A6834 for ; Mon, 21 Sep 2026 04:40:27 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=74.125.228.43 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789965629; cv=none; b=QXqw7O9sKrKApI2FWqBwj2zGRS43BaUnCWwOF4yRHkHDaLn3E45jyI54vNA985m2QZ++q3mNCG3s6Qs2YfNO2+gTTO6dJWdGJwOZpGT62nC2m7SQnxPVAQGLm3X25eIgE5SWA7Cgs4IkVWOV0su8W+6FlWCe2UmbAvoK0S/gVs4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789965629; c=relaxed/simple; bh=jeC4LaMsBa3akjQWVgKWMCdJPuYMgx9lSJHwCRiT4fI=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=aAMglN29HNXLv5RjVqYXzmxi9DXNIlnYfaJn6RwGxRKDWcgO91Ok8vIPW0AOriiLweAKnVek2neQoOPLX9jTBLmU5bZGKDXElfF/CzzuScgcqMkC9Ola7ZfgvGzmGva6I/3D4SoDfRZ6GfQ50/n+gxXyqwEjXQnmIAtBaZFOWRo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=GIMjhW0t; arc=none smtp.client-ip=74.125.228.43 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="GIMjhW0t" Received: by mail-pz2-f43.google.com with SMTP id 41be03b00d2f7-cc4c3304833so1740249a12.3 for ; Sun, 20 Sep 2026 21:40:27 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1789965627; x=1790570427; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to:content-type; bh=y2spstPPyYxdRmmq2UEhNRiouajEznMuECBtSYufh90=; b=GIMjhW0tg7wnSBN09CIB+VPoKDSQOr6qvD0MJMQsFfOWZi8lClmTEkK28k8fnV04Vf w9VknH0liSFpmq52cIutcJYLEp684xjO5dgWbglFZKOd6msHT/KgNT1bCrt6UBcd+nny /6Dd79RpibYmPaswrzOXomXPUUFn4UpvSDt2QPoFbW7jHSAzT+rhy7ljR+qUyV2iB/Fg d5uz/A+8FYKIf19I+s4N43/cgWls3lvph99N0EpWdFjuP+JRdp6R81IIXosUuVEyyzlA PXu6mdSOkA8RdOFV+10GjiTU94G0dS6aavPyrCEWLATGmHT+olLSEtFntICFhmXSuW03 q7Hw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20260707; t=1789965627; x=1790570427; h=content-transfer-encoding:mime-version:references:in-reply-to :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=y2spstPPyYxdRmmq2UEhNRiouajEznMuECBtSYufh90=; b=fe4wKk5eVBfADnMCQz9wrJZMjfSf1p10fpOHyybzE8BeQ02M4b/OHtvCFYXcBPfMDG OV7MICgu4QVrJF+UmGMhgyx+BHxakMmaegCMo30mZfPXs57M25qTf6jcvGkPlRQkIVXU PnT+WYqO+hTlAf9ybtGim5HetabHQyTWeHpLbJoL73CxrvUAeaug8wrbR0c/RDkYhdPZ D9BlmpMPMTsU7ssVZ7wW1+F9rJqdYLJzDWfWM4MFsLQdYMiOaPODvVduFjgrIIQGqI9p 27FvbDaBXme/MA2pBS73WZY+S+ZfftHXOYPjO+ZnP/RHVI4ExpINbr5zlKb4b6+J0hiM CXqg== X-Forwarded-Encrypted: i=1; AKwUvByX5wK1JGcObfp1k6X8PauaI8cE8isQcRuOoF7bPGmnU90dx/HdflJBZ91WI5OSumm88nfNH+A=@vger.kernel.org X-Gm-Message-State: AFuF++lthNVGvwIR5ECQ96AAE1hrz09Mr6DFofqpoaaqLTxO/a1D44DH CFVZ+7bL/9zYKQUGxzq1KChIbZeXwrjpM5+DGb2xlDXlHtgaL9xu3dMO X-Gm-Gg: AYBFou0hTXkPWS42L4kOMMc/OLwL8NSF9cJXBd7IimThiTofdkDSBTWdgOp+YTBgkRS 0lXgkNl0Hl5k1U7aPgvhdLg4sXkVbRqSB+i7LzXFvQNxIsOiVUcMFRQAnnQ4/+0pcHtHWS5kyKw poSjZDciTxU9iqk34fCiftIrH7T49npUyzkOE44afpFerEEUA3UfP5iet7yvqayXm5XV0vCtn+y fFlhLeNga0cS5WlKE2ys5LQKbKll9xWDg0+ZURSs6+/oForukZfg/up4zkVxk8pgsnl76U+wmMz L1ecTo3T+g9YOvDu/vQ6UyBZfFYiPj6EFyqUzvBOPheP952h9bNhS66aRIyp2HUg3KRMU1QCEg/ 976gG/8G5BBWt8tNnOR4/id8EaxMZeOl/d9YWSV81qMwJz6eMf3uo7F7RdREUntu5i4EPDc0jt7 Rn7xZGPdSvaTJ1jF/PY35x8sZNOqhnwig7/lXALF5wma/SA+HjgsrxPQ0hcsG9Um0UVCFSjb4OH xzLUGfbzWJfmpBCdFi07xOkx6f/UQ3UvtYeKx8zahZK8j3OoWghs+Z8DzshECFf4+Hc/SNA9qKw x9NPvXW8R0w3Yk1cDFN7 X-Received: by 2002:a17:90b:2e0b:b0:39e:6c69:34d6 with SMTP id 98e67ed59e1d1-39e6c693688mr8433324a91.58.1789965627199; Sun, 20 Sep 2026 21:40:27 -0700 (PDT) Received: from phui-2.c.googlers.com.com (78.123.83.34.bc.googleusercontent.com. [34.83.123.78]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-3a02526e27dsm4604260a91.0.2026.09.20.21.40.26 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 20 Sep 2026 21:40:26 -0700 (PDT) From: Hui Peng To: Andrea Mayer , "David S . Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni Cc: Hangbin Liu , Simon Horman , David Lebrun , netdev@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org, Hui Peng Subject: [PATCH net v2] ipv6: sr: enforce exact attribute length for SEG6_ATTR_DST Date: Mon, 21 Sep 2026 04:40:25 +0000 Message-ID: <20260921044025.1535982-1-benquike@gmail.com> X-Mailer: git-send-email 2.55.0.1082.g2b9226bbc0-goog In-Reply-To: References: Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit In seg6_genl_policy, SEG6_ATTR_DST is defined with .type = NLA_BINARY and .len = sizeof(struct in6_addr). For NLA_BINARY, .len only enforces the maximum payload length and permits shorter payloads (e.g., 0 bytes). When seg6_genl_set_tunsrc() copies sizeof(struct in6_addr) bytes via kmemdup(val, sizeof(*val), GFP_KERNEL), a short SEG6_ATTR_DST attribute triggers a 16-byte out-of-bounds read past skb->tail into uninitialized skb->head memory, which is stored in sdata->tun_src and leaked back to userspace via SEG6_CMD_GET_TUNSRC. Switch SEG6_ATTR_DST in seg6_genl_policy to NLA_POLICY_EXACT_LEN(sizeof(struct in6_addr)) so that generic netlink validation rejects any attribute whose length is not exactly sizeof(struct in6_addr) with -ERANGE. Tested in QEMU against Linux 7.3.0-rc3 by sending a SEG6_CMD_SET_TUNSRC Generic Netlink message with a 0-byte SEG6_ATTR_DST attribute followed by SEG6_CMD_GET_TUNSRC. On the unfixed kernel, SEG6_CMD_SET_TUNSRC succeeds (err = 0) and SEG6_CMD_GET_TUNSRC leaks 16 bytes of uninitialized kernel heap memory (tun_src = 836a61ecc4d25a1042a8d60411cfb378); with this patch applied, SEG6_CMD_SET_TUNSRC is rejected by netlink policy validation with -ERANGE (-34) and tun_src remains zeroed. Fixes: 915d7e5e5930 ("ipv6: sr: add code base for control plane support of SR-IPv6") Cc: stable@vger.kernel.org Assisted-by: LLM Signed-off-by: Hui Peng --- Changes in v2: - Drop the redundant nla_len(info->attrs[SEG6_ATTR_DST]) != sizeof(struct in6_addr) check in seg6_genl_set_tunsrc() since NLA_POLICY_EXACT_LEN() in seg6_genl_policy already enforces the exact length, as pointed out by Hangbin Liu. net/ipv6/seg6.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/net/ipv6/seg6.c b/net/ipv6/seg6.c index 62a7eb779202..8c2b156c227a 100644 --- a/net/ipv6/seg6.c +++ b/net/ipv6/seg6.c @@ -138,8 +138,8 @@ void seg6_icmp_srh(struct sk_buff *skb, struct inet6_skb_parm *opt) static struct genl_family seg6_genl_family; static const struct nla_policy seg6_genl_policy[SEG6_ATTR_MAX + 1] = { - [SEG6_ATTR_DST] = { .type = NLA_BINARY, - .len = sizeof(struct in6_addr) }, + [SEG6_ATTR_DST] = + NLA_POLICY_EXACT_LEN(sizeof(struct in6_addr)), [SEG6_ATTR_DSTLEN] = { .type = NLA_S32, }, [SEG6_ATTR_HMACKEYID] = { .type = NLA_U32, }, [SEG6_ATTR_SECRET] = { .type = NLA_BINARY, }, -- 2.49.0