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authorGuillaume Chazarain <guichaz@yahoo.fr>2006-07-21 14:45:25 -0700
committerDavid S. Miller <davem@davemloft.net>2006-07-21 14:45:25 -0700
commit89e1df74f841fc31e81838d30594c4eff01859f8 (patch)
treea9a8069feccad982642f932ccef01f64a1391796
parentfbeff3c1d35d07b1f967e47fcfb00cd16b7ecd02 (diff)
[PKT_SCHED] netem: Fix slab corruption with netem (2nd try)
CONFIG_DEBUG_SLAB found the following bug: netem_enqueue() in sch_netem.c gets a pointer inside a slab object: struct netem_skb_cb *cb = (struct netem_skb_cb *)skb->cb; But then, the slab object may be freed: skb = skb_unshare(skb, GFP_ATOMIC) cb is still pointing inside the freed skb, so here is a patch to initialize cb later, and make it clear that initializing it sooner is a bad idea. [From Stephen Hemminger: leave cb unitialized in order to let gcc complain in case of use before initialization] Signed-off-by: Guillaume Chazarain <guichaz@yahoo.fr> Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r--net/sched/sch_netem.c4
1 files changed, 3 insertions, 1 deletions
diff --git a/net/sched/sch_netem.c b/net/sched/sch_netem.c
index c5bd8064e6d..a08ec4c7c55 100644
--- a/net/sched/sch_netem.c
+++ b/net/sched/sch_netem.c
@@ -148,7 +148,8 @@ static long tabledist(unsigned long mu, long sigma,
static int netem_enqueue(struct sk_buff *skb, struct Qdisc *sch)
{
struct netem_sched_data *q = qdisc_priv(sch);
- struct netem_skb_cb *cb = (struct netem_skb_cb *)skb->cb;
+ /* We don't fill cb now as skb_unshare() may invalidate it */
+ struct netem_skb_cb *cb;
struct sk_buff *skb2;
int ret;
int count = 1;
@@ -200,6 +201,7 @@ static int netem_enqueue(struct sk_buff *skb, struct Qdisc *sch)
skb->data[net_random() % skb_headlen(skb)] ^= 1<<(net_random() % 8);
}
+ cb = (struct netem_skb_cb *)skb->cb;
if (q->gap == 0 /* not doing reordering */
|| q->counter < q->gap /* inside last reordering gap */
|| q->reorder < get_crandom(&q->reorder_cor)) {