path: root/net/ipv4/tcp_output.c
diff options
authorHerbert Xu <>2006-04-18 13:24:14 -0700
committerDavid S. Miller <>2006-04-18 15:57:49 -0700
commitef5cb9738b488140eb6c3f32fffab08f39a4905e (patch)
tree803d92cada2f9062417d4b6038482689b0c86f84 /net/ipv4/tcp_output.c
parent385910f2b275a636238f70844f1b6da9fda6f2da (diff)
[TCP]: Fix truesize underflow
There is a problem with the TSO packet trimming code. The cause of this lies in the tcp_fragment() function. When we allocate a fragment for a completely non-linear packet the truesize is calculated for a payload length of zero. This means that truesize could in fact be less than the real payload length. When that happens the TSO packet trimming can cause truesize to become negative. This in turn can cause sk_forward_alloc to be -n * PAGE_SIZE which would trigger the warning. I've copied the code DaveM used in tso_fragment which should work here. Signed-off-by: Herbert Xu <> Signed-off-by: David S. Miller <>
Diffstat (limited to 'net/ipv4/tcp_output.c')
1 files changed, 3 insertions, 1 deletions
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index b871db6adc55..44df1db726a3 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -551,7 +551,9 @@ int tcp_fragment(struct sock *sk, struct sk_buff *skb, u32 len, unsigned int mss
buff = sk_stream_alloc_skb(sk, nsize, GFP_ATOMIC);
if (buff == NULL)
return -ENOMEM; /* We'll just try again later. */
- sk_charge_skb(sk, buff);
+ buff->truesize = skb->len - len;
+ skb->truesize -= buff->truesize;
/* Correct the sequence numbers. */
TCP_SKB_CB(buff)->seq = TCP_SKB_CB(skb)->seq + len;