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[NET_SCHED]: cls_fw: fix NULL pointer dereference 

When the first fw classifier is initialized, there is a small window
between the ->init() and ->change() calls, during which the classifier
is active but not entirely set up and tp->root is still NULL (->init()
does nothing).

When a packet is queued during this window a NULL pointer dereference
occurs in fw_classify() when trying to dereference head->mask;

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Patrick McHardy 2006-12-05 13:46:13 -08:00 committed by David S. Miller
parent f216f082b2
commit 5c804bfdcc
1 changed files with 2 additions and 1 deletions
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3
net/sched/cls_fw.c
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@ -101,9 +101,10 @@ static int fw_classify(struct sk_buff *skb, struct tcf_proto *tp,
struct fw_head *head = (struct fw_head*)tp->root;
struct fw_filter *f;
int r;
u32 id = skb->mark & head->mask;
u32 id = skb->mark;
if (head != NULL) {
id &= head->mask;
for (f=head->ht[fw_hash(id)]; f; f=f->next) {
if (f->id == id) {
*res = f->res;