Thread (6 messages) flat view 6 messages, 2 authors, 2023-12-13

Re: [PATCH net 1/1] net_sched: sch_fq: Fix out of range band computation

From: Eric Dumazet <edumazet@google.com>
Date: 2023-12-13 17:30:12

On Wed, Dec 13, 2023 at 5:57 PM Jamal Hadi Salim [off-list ref] wrote:
quoted hunk ↗ jump to hunk
It is possible to compute a band of 3. Doing so will overrun array
q->band_pkt_count[0-2] boundaries.

Fixes: 29f834aa326e ("net_sched: sch_fq: add 3 bands and WRR scheduling")
Reported-by: Coverity Scan <redacted>
Signed-off-by: Jamal Hadi Salim <jhs@mojatatu.com>
---
 net/sched/sch_fq.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/net/sched/sch_fq.c b/net/sched/sch_fq.c
index 3a31c47fea9b..217c430343df 100644
--- a/net/sched/sch_fq.c
+++ b/net/sched/sch_fq.c
@@ -159,7 +159,7 @@ struct fq_sched_data {
 /* return the i-th 2-bit value ("crumb") */
 static u8 fq_prio2band(const u8 *prio2band, unsigned int prio)
 {
-       return (prio2band[prio / 4] >> (2 * (prio & 0x3))) & 0x3;
+       return (prio2band[prio / 4] >> (2 * (prio & 0x3))) % 0x3;
 }
Are you sure this is needed ?

fq_load_priomap() makes sure this can not happen...
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