perturb_period is currently a signed integer, but I can't see any good
reason why this is so--a negative perturbation period will add a timer
that expires in the past, causing constant perturbation, which makes
hashing useless.
if (q->perturb_period) {
q->perturb_timer.expires = jiffies + q->perturb_period;
add_timer(&q->perturb_timer);
}
Strictly speaking, this will break binary compatibility with older
versions of tc, but that ought not to be a problem because (a) there's
no valid use for a negative perturb_period, and (b) negative values
will be seen as high values (> INT_MAX), which don't work anyway.
If perturb_period is too large, (perturb_period * HZ) will overflow the
size of an unsigned int and wrap around. So, check for thet and reject
values that are too high.
Signed-off-by: Corey Hickey <[EMAIL PROTECTED]>
---
include/linux/pkt_sched.h | 2 +-
net/sched/sch_sfq.c | 8 ++++++--
2 files changed, 7 insertions(+), 3 deletions(-)
diff --git a/include/linux/pkt_sched.h b/include/linux/pkt_sched.h
index 58a0ea6..8559974 100644
--- a/include/linux/pkt_sched.h
+++ b/include/linux/pkt_sched.h
@@ -142,7 +142,7 @@ enum
struct tc_sfq_qopt
{
unsigned quantum; /* Bytes per round allocated to flow */
- int perturb_period; /* Period of hash perturbation */
+ unsigned perturb_period; /* Period of hash perturbation */
__u32 limit; /* Maximal packets in queue */
unsigned divisor; /* Hash divisor */
unsigned flows; /* Maximal number of flows */
diff --git a/net/sched/sch_sfq.c b/net/sched/sch_sfq.c
index 2d3cc38..170fd37 100644
--- a/net/sched/sch_sfq.c
+++ b/net/sched/sch_sfq.c
@@ -74,6 +74,9 @@
typedef unsigned int sfq_index;
#define SFQ_MAX_DEPTH (UINT_MAX / 2 - 1)
+/* We don't want perturb_period * HZ to overflow an unsigned int. */
+#define SFQ_MAX_PERTURB (UINT_MAX / HZ)
+
struct sfq_head
{
sfq_index next;
@@ -83,7 +86,7 @@ struct sfq_head
struct sfq_sched_data
{
/* Parameters */
- int perturb_period;
+ unsigned perturb_period;
unsigned quantum; /* Allotment per round: MUST BE >= MTU
*/
int limit;
unsigned depth;
@@ -441,7 +444,8 @@ sfq_q_init(struct sfq_sched_data *q, struct rtattr *opt)
if (ctl->limit)
q->limit = ctl->limit;
- if (q->depth > SFQ_MAX_DEPTH)
+ if (q->perturb_period > SFQ_MAX_PERTURB ||
+ q->depth > SFQ_MAX_DEPTH)
return -EINVAL;
}
q->limit = min_t(u32, q->limit, q->depth - 2);
--
1.5.3
-
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