diff options
| author | Eric Dumazet <edumazet@google.com> | 2016-11-10 13:12:35 -0800 |
|---|---|---|
| committer | Ben Hutchings <ben@decadent.org.uk> | 2017-02-23 03:54:46 +0000 |
| commit | 3d59e6e25fd0cbe700d3f2910291729227dcfd23 (patch) | |
| tree | 8312731650495f8e18cd495a072a2cda14cfb285 | |
| parent | 49bbb1dc818f09bfb323ce5b36c47306ad9e94ac (diff) | |
tcp: take care of truncations done by sk_filter()
commit ac6e780070e30e4c35bd395acfe9191e6268bdd3 upstream.
With syzkaller help, Marco Grassi found a bug in TCP stack,
crashing in tcp_collapse()
Root cause is that sk_filter() can truncate the incoming skb,
but TCP stack was not really expecting this to happen.
It probably was expecting a simple DROP or ACCEPT behavior.
We first need to make sure no part of TCP header could be removed.
Then we need to adjust TCP_SKB_CB(skb)->end_seq
Many thanks to syzkaller team and Marco for giving us a reproducer.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Marco Grassi <marco.gra@gmail.com>
Reported-by: Vladis Dronov <vdronov@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
| -rw-r--r-- | include/net/tcp.h | 1 | ||||
| -rw-r--r-- | net/ipv4/tcp_ipv4.c | 19 | ||||
| -rw-r--r-- | net/ipv6/tcp_ipv6.c | 6 |
3 files changed, 23 insertions, 3 deletions
diff --git a/include/net/tcp.h b/include/net/tcp.h index 60e2dc5cef26..ceaa03fdccf2 100644 --- a/include/net/tcp.h +++ b/include/net/tcp.h @@ -1053,6 +1053,7 @@ static inline void tcp_prequeue_init(struct tcp_sock *tp) } bool tcp_prequeue(struct sock *sk, struct sk_buff *skb); +int tcp_filter(struct sock *sk, struct sk_buff *skb); #undef STATE_TRACE diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c index 6b4c3e3639bf..f66f033c51fe 100644 --- a/net/ipv4/tcp_ipv4.c +++ b/net/ipv4/tcp_ipv4.c @@ -1697,6 +1697,21 @@ bool tcp_prequeue(struct sock *sk, struct sk_buff *skb) } EXPORT_SYMBOL(tcp_prequeue); +int tcp_filter(struct sock *sk, struct sk_buff *skb) +{ + struct tcphdr *th = (struct tcphdr *)skb->data; + unsigned int eaten = skb->len; + int err; + + err = sk_filter_trim_cap(sk, skb, th->doff * 4); + if (!err) { + eaten -= skb->len; + TCP_SKB_CB(skb)->end_seq -= eaten; + } + return err; +} +EXPORT_SYMBOL(tcp_filter); + /* * From tcp_input.c */ @@ -1760,8 +1775,10 @@ process: goto discard_and_relse; nf_reset(skb); - if (sk_filter(sk, skb)) + if (tcp_filter(sk, skb)) goto discard_and_relse; + th = (const struct tcphdr *)skb->data; + iph = ip_hdr(skb); sk_mark_napi_id(sk, skb); skb->dev = NULL; diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c index 427d164aad46..c6c921d15de4 100644 --- a/net/ipv6/tcp_ipv6.c +++ b/net/ipv6/tcp_ipv6.c @@ -1359,7 +1359,7 @@ static int tcp_v6_do_rcv(struct sock *sk, struct sk_buff *skb) goto discard; #endif - if (sk_filter(sk, skb)) + if (tcp_filter(sk, skb)) goto discard; /* @@ -1531,8 +1531,10 @@ process: if (!xfrm6_policy_check(sk, XFRM_POLICY_IN, skb)) goto discard_and_relse; - if (sk_filter(sk, skb)) + if (tcp_filter(sk, skb)) goto discard_and_relse; + th = (const struct tcphdr *)skb->data; + hdr = ipv6_hdr(skb); sk_mark_napi_id(sk, skb); skb->dev = NULL; |