[TCP]: Fix truesize underflow
authorHerbert Xu <herbert@gondor.apana.org.au>
Tue, 18 Apr 2006 20:24:14 +0000 (13:24 -0700)
committerDavid S. Miller <davem@sunset.davemloft.net>
Tue, 18 Apr 2006 22:57:49 +0000 (15:57 -0700)
commitef5cb9738b488140eb6c3f32fffab08f39a4905e
tree803d92cada2f9062417d4b6038482689b0c86f84
parent385910f2b275a636238f70844f1b6da9fda6f2da
[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 <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
net/ipv4/tcp_output.c