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tipc: fix skb truesize/datasize ratio control

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In commit d618d09a68 ("tipc: enforce valid ratio between skb truesize
and contents") we introduced a test for ensuring that the condition
truesize/datasize <= 4 is true for a received buffer. Unfortunately this
test has two problems.

- Because of the integer arithmetics the test
  if (skb->truesize / buf_roundup_len(skb) > 4) will miss all
  ratios [4 < ratio < 5], which was not the intention.
- The buffer returned by skb_copy() inherits skb->truesize of the
  original buffer, which doesn't help the situation at all.

In this commit, we change the ratio condition and replace skb_copy()
with a call to skb_copy_expand() to finally get this right.

Acked-by: Jon Maloy <jon.maloy@ericsson.com>
Signed-off-by: Jon Maloy <jon.maloy@ericsson.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Hoang Le 2018-02-08 17:16:25 +01:00 committed by David S. Miller
parent eb53f7af6f
commit 55b3280d1e
1 changed files with 2 additions and 2 deletions
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4
net/tipc/msg.c
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@ -208,8 +208,8 @@ bool tipc_msg_validate(struct sk_buff **_skb)
int msz, hsz;
/* Ensure that flow control ratio condition is satisfied */
if (unlikely(skb->truesize / buf_roundup_len(skb) > 4)) {
skb = skb_copy(skb, GFP_ATOMIC);
if (unlikely(skb->truesize / buf_roundup_len(skb) >= 4)) {
skb = skb_copy_expand(skb, BUF_HEADROOM, 0, GFP_ATOMIC);
if (!skb)
return false;
kfree_skb(*_skb);