From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 7DB7E63BB for ; Sun, 17 Sep 2023 19:36:23 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id E03FCC433C7; Sun, 17 Sep 2023 19:36:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1694979383; bh=hZqkfXmm2z0Zu4iTgwMSz52DAc4tyQJdEl8Ghoce75g=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ScL5G0eNT+RLtwanhfO2J6H3qmGYBt4D4OjXMSulds6XmPEkh2jRycmobdTJoAcYO Gy5jz235+IDA2w3Ds4tlyDXr/rVE1/vBbKcbDc1OIq/Dta8fWc+KNF0+SMt3eRwkvG 0yjzTFd0xZw7cI/sGCnZ/cDdJqypIIdSGpIjV0oY= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Jann Horn , Kuniyuki Iwashima , "David S. Miller" Subject: [PATCH 5.10 296/406] dccp: Fix out of bounds access in DCCP error handler Date: Sun, 17 Sep 2023 21:12:30 +0200 Message-ID: <20230917191109.128060940@linuxfoundation.org> X-Mailer: git-send-email 2.42.0 In-Reply-To: <20230917191101.035638219@linuxfoundation.org> References: <20230917191101.035638219@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 5.10-stable review patch. If anyone has any objections, please let me know. ------------------ From: Jann Horn commit 977ad86c2a1bcaf58f01ab98df5cc145083c489c upstream. There was a previous attempt to fix an out-of-bounds access in the DCCP error handlers, but that fix assumed that the error handlers only want to access the first 8 bytes of the DCCP header. Actually, they also look at the DCCP sequence number, which is stored beyond 8 bytes, so an explicit pskb_may_pull() is required. Fixes: 6706a97fec96 ("dccp: fix out of bound access in dccp_v4_err()") Fixes: 1aa9d1a0e7ee ("ipv6: dccp: fix out of bound access in dccp_v6_err()") Cc: stable@vger.kernel.org Signed-off-by: Jann Horn Reviewed-by: Kuniyuki Iwashima Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/dccp/ipv4.c | 13 +++++++++---- net/dccp/ipv6.c | 15 ++++++++++----- 2 files changed, 19 insertions(+), 9 deletions(-) --- a/net/dccp/ipv4.c +++ b/net/dccp/ipv4.c @@ -243,12 +243,17 @@ static int dccp_v4_err(struct sk_buff *s int err; struct net *net = dev_net(skb->dev); - /* Only need dccph_dport & dccph_sport which are the first - * 4 bytes in dccp header. + /* For the first __dccp_basic_hdr_len() check, we only need dh->dccph_x, + * which is in byte 7 of the dccp header. * Our caller (icmp_socket_deliver()) already pulled 8 bytes for us. + * + * Later on, we want to access the sequence number fields, which are + * beyond 8 bytes, so we have to pskb_may_pull() ourselves. */ - BUILD_BUG_ON(offsetofend(struct dccp_hdr, dccph_sport) > 8); - BUILD_BUG_ON(offsetofend(struct dccp_hdr, dccph_dport) > 8); + dh = (struct dccp_hdr *)(skb->data + offset); + if (!pskb_may_pull(skb, offset + __dccp_basic_hdr_len(dh))) + return -EINVAL; + iph = (struct iphdr *)skb->data; dh = (struct dccp_hdr *)(skb->data + offset); sk = __inet_lookup_established(net, &dccp_hashinfo, --- a/net/dccp/ipv6.c +++ b/net/dccp/ipv6.c @@ -67,7 +67,7 @@ static inline __u64 dccp_v6_init_sequenc static int dccp_v6_err(struct sk_buff *skb, struct inet6_skb_parm *opt, u8 type, u8 code, int offset, __be32 info) { - const struct ipv6hdr *hdr = (const struct ipv6hdr *)skb->data; + const struct ipv6hdr *hdr; const struct dccp_hdr *dh; struct dccp_sock *dp; struct ipv6_pinfo *np; @@ -76,12 +76,17 @@ static int dccp_v6_err(struct sk_buff *s __u64 seq; struct net *net = dev_net(skb->dev); - /* Only need dccph_dport & dccph_sport which are the first - * 4 bytes in dccp header. + /* For the first __dccp_basic_hdr_len() check, we only need dh->dccph_x, + * which is in byte 7 of the dccp header. * Our caller (icmpv6_notify()) already pulled 8 bytes for us. + * + * Later on, we want to access the sequence number fields, which are + * beyond 8 bytes, so we have to pskb_may_pull() ourselves. */ - BUILD_BUG_ON(offsetofend(struct dccp_hdr, dccph_sport) > 8); - BUILD_BUG_ON(offsetofend(struct dccp_hdr, dccph_dport) > 8); + dh = (struct dccp_hdr *)(skb->data + offset); + if (!pskb_may_pull(skb, offset + __dccp_basic_hdr_len(dh))) + return -EINVAL; + hdr = (const struct ipv6hdr *)skb->data; dh = (struct dccp_hdr *)(skb->data + offset); sk = __inet6_lookup_established(net, &dccp_hashinfo,