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dccp: Fix out of bounds access in DCCP error handler
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:6706a97fec
("dccp: fix out of bound access in dccp_v4_err()") Fixes:1aa9d1a0e7
("ipv6: dccp: fix out of bound access in dccp_v6_err()") Cc: stable@vger.kernel.org Signed-off-by: Jann Horn <jannh@google.com> Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com> Signed-off-by: David S. Miller <davem@davemloft.net>
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@ -255,12 +255,17 @@ static int dccp_v4_err(struct sk_buff *skb, u32 info)
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int err;
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struct net *net = dev_net(skb->dev);
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/* Only need dccph_dport & dccph_sport which are the first
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* 4 bytes in dccp header.
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/* For the first __dccp_basic_hdr_len() check, we only need dh->dccph_x,
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* which is in byte 7 of the dccp header.
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* Our caller (icmp_socket_deliver()) already pulled 8 bytes for us.
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*
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* Later on, we want to access the sequence number fields, which are
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* beyond 8 bytes, so we have to pskb_may_pull() ourselves.
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*/
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BUILD_BUG_ON(offsetofend(struct dccp_hdr, dccph_sport) > 8);
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BUILD_BUG_ON(offsetofend(struct dccp_hdr, dccph_dport) > 8);
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dh = (struct dccp_hdr *)(skb->data + offset);
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if (!pskb_may_pull(skb, offset + __dccp_basic_hdr_len(dh)))
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return -EINVAL;
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iph = (struct iphdr *)skb->data;
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dh = (struct dccp_hdr *)(skb->data + offset);
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sk = __inet_lookup_established(net, &dccp_hashinfo,
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@ -74,7 +74,7 @@ static inline __u64 dccp_v6_init_sequence(struct sk_buff *skb)
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static int dccp_v6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
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u8 type, u8 code, int offset, __be32 info)
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{
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const struct ipv6hdr *hdr = (const struct ipv6hdr *)skb->data;
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const struct ipv6hdr *hdr;
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const struct dccp_hdr *dh;
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struct dccp_sock *dp;
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struct ipv6_pinfo *np;
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@ -83,12 +83,17 @@ static int dccp_v6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
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__u64 seq;
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struct net *net = dev_net(skb->dev);
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/* Only need dccph_dport & dccph_sport which are the first
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* 4 bytes in dccp header.
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/* For the first __dccp_basic_hdr_len() check, we only need dh->dccph_x,
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* which is in byte 7 of the dccp header.
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* Our caller (icmpv6_notify()) already pulled 8 bytes for us.
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*
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* Later on, we want to access the sequence number fields, which are
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* beyond 8 bytes, so we have to pskb_may_pull() ourselves.
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*/
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BUILD_BUG_ON(offsetofend(struct dccp_hdr, dccph_sport) > 8);
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BUILD_BUG_ON(offsetofend(struct dccp_hdr, dccph_dport) > 8);
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dh = (struct dccp_hdr *)(skb->data + offset);
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if (!pskb_may_pull(skb, offset + __dccp_basic_hdr_len(dh)))
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return -EINVAL;
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hdr = (const struct ipv6hdr *)skb->data;
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dh = (struct dccp_hdr *)(skb->data + offset);
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sk = __inet6_lookup_established(net, &dccp_hashinfo,
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