tcp: limit payload size of sacked skbs

[pandora-kernel.git] / net / ipv4 / tcp_input.c

diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 73a4355..7db2297 100644 (file)
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -1431,7 +1431,7 @@ static int tcp_shifted_skb(struct sock *sk, struct sk_buff *skb,
        TCP_SKB_CB(skb)->seq += shifted;
 
        skb_shinfo(prev)->gso_segs += pcount;
-       BUG_ON(skb_shinfo(skb)->gso_segs < pcount);
+       WARN_ON_ONCE(tcp_skb_pcount(skb) < pcount);
        skb_shinfo(skb)->gso_segs -= pcount;
 
        /* When we're adding to gso_segs == 1, gso_size will be zero,
@@ -1499,6 +1499,21 @@ static int skb_can_shift(const struct sk_buff *skb)
        return !skb_headlen(skb) && skb_is_nonlinear(skb);
 }
 
+int tcp_skb_shift(struct sk_buff *to, struct sk_buff *from,
+                 int pcount, int shiftlen)
+{
+       /* TCP min gso_size is 8 bytes (TCP_MIN_GSO_SIZE)
+        * Since TCP_SKB_CB(skb)->tcp_gso_segs is 16 bits, we need
+        * to make sure not storing more than 65535 * 8 bytes per skb,
+        * even if current MSS is bigger.
+        */
+       if (unlikely(to->len + shiftlen >= 65535 * TCP_MIN_GSO_SIZE))
+               return 0;
+       if (unlikely(tcp_skb_pcount(to) + pcount > 65535))
+               return 0;
+       return skb_shift(to, from, shiftlen);
+}
+
 /* Try collapsing SACK blocks spanning across multiple skbs to a single
  * skb.
  */
@@ -1510,6 +1525,7 @@ static struct sk_buff *tcp_shift_skb_data(struct sock *sk, struct sk_buff *skb,
        struct tcp_sock *tp = tcp_sk(sk);
        struct sk_buff *prev;
        int mss;
+       int next_pcount;
        int pcount = 0;
        int len;
        int in_sack;
@@ -1604,7 +1620,7 @@ static struct sk_buff *tcp_shift_skb_data(struct sock *sk, struct sk_buff *skb,
        if (!after(TCP_SKB_CB(skb)->seq + len, tp->snd_una))
                goto fallback;
 
-       if (!skb_shift(prev, skb, len))
+       if (!tcp_skb_shift(prev, skb, pcount, len))
                goto fallback;
        if (!tcp_shifted_skb(sk, skb, state, pcount, len, mss, dup_sack))
                goto out;
@@ -1623,9 +1639,10 @@ static struct sk_buff *tcp_shift_skb_data(struct sock *sk, struct sk_buff *skb,
                goto out;
 
        len = skb->len;
-       if (skb_shift(prev, skb, len)) {
-               pcount += tcp_skb_pcount(skb);
-               tcp_shifted_skb(sk, skb, state, tcp_skb_pcount(skb), len, mss, 0);
+       next_pcount = tcp_skb_pcount(skb);
+       if (tcp_skb_shift(prev, skb, next_pcount, len)) {
+               pcount += next_pcount;
+               tcp_shifted_skb(sk, skb, state, next_pcount, len, mss, 0);
        }
 
 out: