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Commit db2c2417 authored by Changli Gao's avatar Changli Gao Committed by David S. Miller
Browse files

act_pedit: access skb->data safely 



access skb->data safely

we should use skb_header_pointer() and skb_store_bits() to access skb->data to
handle small or non-linear skbs.

Signed-off-by: default avatarChangli Gao <xiaosuo@gmail.com>
----
 net/sched/act_pedit.c |   24 ++++++++++++++----------
 1 file changed, 14 insertions(+), 10 deletions(-)
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 3df95ce9

net/sched/act_pedit.c

+14 −10
Original line number Diff line number Diff line
@@ -125,7 +125,7 @@ static int tcf_pedit(struct sk_buff *skb, struct tc_action *a, 
{

	struct tcf_pedit *p = a->priv;

	int i, munged = 0;

	u8 *pptr;

	unsigned int off;



	if (!(skb->tc_verd & TC_OK2MUNGE)) {

		/* should we set skb->cloned? */
@@ -134,7 +134,7 @@ static int tcf_pedit(struct sk_buff *skb, struct tc_action *a, 
		}

	}



	pptr = skb_network_header(skb);

	off = skb_network_offset(skb);



	spin_lock(&p->tcf_lock);
@@ -144,17 +144,17 @@ static int tcf_pedit(struct sk_buff *skb, struct tc_action *a, 
		struct tc_pedit_key *tkey = p->tcfp_keys;



		for (i = p->tcfp_nkeys; i > 0; i--, tkey++) {

			u32 *ptr;

			u32 *ptr, _data;

			int offset = tkey->off;



			if (tkey->offmask) {

				if (skb->len > tkey->at) {

					 char *j = pptr + tkey->at;

					 offset += ((*j & tkey->offmask) >>

						   tkey->shift);

				} else {

				char *d, _d;



				d = skb_header_pointer(skb, off + tkey->at, 1,

						       &_d);

				if (!d)

					goto bad;

				}

				offset += (*d & tkey->offmask) >> tkey->shift;

			}



			if (offset % 4) {
@@ -169,9 +169,13 @@ static int tcf_pedit(struct sk_buff *skb, struct tc_action *a, 
				goto bad;

			}



			ptr = (u32 *)(pptr+offset);

			ptr = skb_header_pointer(skb, off + offset, 4, &_data);

			if (!ptr)

				goto bad;

			/* just do it, baby */

			*ptr = ((*ptr & tkey->mask) ^ tkey->val);

			if (ptr == &_data)

				skb_store_bits(skb, off + offset, ptr, 4);

			munged++;

		}