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| author | Jann Horn <jannh@google.com> | 2023-08-25 15:32:41 +0200 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2023-08-28 10:15:56 +0100 |
| commit | 977ad86c2a1bcaf58f01ab98df5cc145083c489c (patch) | |
| tree | 9dc2b01ca19fed1db648ac231e9a67a1ef156dc6 /net | |
| parent | 72dd7e427e16fca901daaa399e4b0893c3bb85c0 (diff) | |
| download | lwn-977ad86c2a1bcaf58f01ab98df5cc145083c489c.tar.gz lwn-977ad86c2a1bcaf58f01ab98df5cc145083c489c.zip | |
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: 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 <jannh@google.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net')
| -rw-r--r-- | net/dccp/ipv4.c | 13 | ||||
| -rw-r--r-- | net/dccp/ipv6.c | 15 |
2 files changed, 19 insertions, 9 deletions
diff --git a/net/dccp/ipv4.c b/net/dccp/ipv4.c index a545ad71201c..a5361fb7a415 100644 --- a/net/dccp/ipv4.c +++ b/net/dccp/ipv4.c @@ -255,12 +255,17 @@ static int dccp_v4_err(struct sk_buff *skb, u32 info) 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, diff --git a/net/dccp/ipv6.c b/net/dccp/ipv6.c index d29d1163203d..25816e790527 100644 --- a/net/dccp/ipv6.c +++ b/net/dccp/ipv6.c @@ -74,7 +74,7 @@ static inline __u64 dccp_v6_init_sequence(struct sk_buff *skb) 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; @@ -83,12 +83,17 @@ static int dccp_v6_err(struct sk_buff *skb, struct inet6_skb_parm *opt, __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, |