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| author | Eric Dumazet <edumazet@google.com> | 2016-11-10 13:12:35 -0800 |
|---|---|---|
| committer | Ben Hutchings <ben@decadent.org.uk> | 2017-02-23 03:51:05 +0000 |
| commit | 1433b66208118028d7f1a5fc235f2660badb6c05 (patch) | |
| tree | 2ecefba4d041720b5e72482916a8018fa1fca7e2 | |
| parent | 9b2e057859a2edb5daef515f70fb3db2d3915192 (diff) | |
| download | linux-1433b66208118028d7f1a5fc235f2660badb6c05.tar.gz linux-1433b66208118028d7f1a5fc235f2660badb6c05.tar.bz2 linux-1433b66208118028d7f1a5fc235f2660badb6c05.zip | |
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 3.2: 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 0f4e1d419bfb..95c4211f47a7 100644 --- a/include/net/tcp.h +++ b/include/net/tcp.h @@ -966,6 +966,7 @@ static inline int tcp_prequeue(struct sock *sk, struct sk_buff *skb) return 1; } +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 b4e0eb49f56d..4ba77eea6b85 100644 --- a/net/ipv4/tcp_ipv4.c +++ b/net/ipv4/tcp_ipv4.c @@ -1647,6 +1647,21 @@ csum_err: } EXPORT_SYMBOL(tcp_v4_do_rcv); +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 */ @@ -1709,8 +1724,10 @@ 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); skb->dev = NULL; diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c index b20f7a08b4f7..2c2d71123251 100644 --- a/net/ipv6/tcp_ipv6.c +++ b/net/ipv6/tcp_ipv6.c @@ -1585,7 +1585,7 @@ 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; /* @@ -1743,8 +1743,10 @@ 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); skb->dev = NULL; |