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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: Changli Gao <xiaosuo@gmail.com>
----
 net/sched/act_pedit.c |   24 ++++++++++++++----------
 1 file changed, 14 insertions(+), 10 deletions(-)
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Changli Gao 2010-06-02 04:55:02 +00:00 committed by David S. Miller
parent 3df95ce948
commit db2c24175d
1 changed files with 14 additions and 10 deletions
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24
net/sched/act_pedit.c
View File

@ -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++;
}