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dccp: Fix out of bounds access in DCCP error handler

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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>
This commit is contained in:
Jann Horn 2023-08-25 15:32:41 +02:00 committed by David S. Miller
parent 72dd7e427e
commit 977ad86c2a
2 changed files with 19 additions and 9 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

13
net/dccp/ipv4.c
View file

@ -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,

15
net/dccp/ipv6.c
View file

@ -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,