Commit 55b3280d authored Feb 08, 2018 by Hoang Le Committed by David S. Miller Feb 08, 2018

tipc: fix skb truesize/datasize ratio control



In commit d618d09a ("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>

parent eb53f7af

net/tipc/msg.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -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);

Admin message