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[34.83.123.78]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2ddc17888b9sm12897385ad.23.2026.09.19.13.48.07 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 19 Sep 2026 13:48:07 -0700 (PDT) From: Hui Peng To: Andrea Mayer , "David S . Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni Cc: Simon Horman , netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH] ipv6: sr: fix 16-byte kernel heap leak in seg6_genl_set_tunsrc() Date: Sat, 19 Sep 2026 20:48:06 +0000 Message-ID: <20260919204807.2812472-1-benquike@gmail.com> X-Mailer: git-send-email 2.55.0.1082.g2b9226bbc0-goog Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit seg6_genl_policy[SEG6_ATTR_DST] uses NLA_BINARY with .len = sizeof(struct in6_addr), which only caps the maximum attribute length and allows 0-byte SEG6_ATTR_DST attributes. seg6_genl_set_tunsrc() then unconditionally copies sizeof(struct in6_addr) (16 bytes) from nla_data(info->attrs[SEG6_ATTR_DST]) into sdata->tun_src via kmemdup(), reading 16 bytes of uninitialized skb->head heap memory past skb->tail and exposing it to userspace via SEG6_CMD_GET_TUNSRC. Enforce NLA_POLICY_EXACT_LEN(sizeof(struct in6_addr)) in seg6_genl_policy and validate nla_len(info->attrs[SEG6_ATTR_DST]) in seg6_genl_set_tunsrc(). Fixes: 915d7e5e5930 ("ipv6: sr: add code base for control plane support of SR-IPv6") Assisted-by: LLM Signed-off-by: Hui Peng --- diff --git a/net/ipv6/seg6.c b/net/ipv6/seg6.c --- a/net/ipv6/seg6.c +++ b/net/ipv6/seg6.c @@ -138,8 +138,8 @@ out: 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, }, @@ -242,7 +242,8 @@ static int seg6_genl_set_tunsrc(struct sk_buff *skb, struct genl_info *info) sdata = seg6_pernet(net); - if (!info->attrs[SEG6_ATTR_DST]) + if (!info->attrs[SEG6_ATTR_DST] || + nla_len(info->attrs[SEG6_ATTR_DST]) != sizeof(struct in6_addr)) return -EINVAL; val = nla_data(info->attrs[SEG6_ATTR_DST]); -- 2.43.0