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| author | Guillaume Chazarain <guichaz@yahoo.fr> | 2006-07-22 01:45:25 +0400 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2006-07-22 01:45:25 +0400 |
| commit | 89e1df74f841fc31e81838d30594c4eff01859f8 (patch) | |
| tree | a9a8069feccad982642f932ccef01f64a1391796 /net/sched | |
| parent | fbeff3c1d35d07b1f967e47fcfb00cd16b7ecd02 (diff) | |
| download | linux-89e1df74f841fc31e81838d30594c4eff01859f8.tar.xz | |
[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>
Diffstat (limited to 'net/sched')
| -rw-r--r-- | net/sched/sch_netem.c | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/net/sched/sch_netem.c b/net/sched/sch_netem.c index c5bd8064e6d8..a08ec4c7c55d 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)) { |