[tip: irq/urgent] genirq/timings: Prevent potential array overflow in __irq_timings_store()

From: tip-bot2 for Ben Dai
Date: Tue Aug 10 2021 - 09:41:26 EST


The following commit has been merged into the irq/urgent branch of tip:

Commit-ID: b9cc7d8a4656a6e815852c27ab50365009cb69c1
Gitweb: https://git.kernel.org/tip/b9cc7d8a4656a6e815852c27ab50365009cb69c1
Author: Ben Dai <ben.dai@xxxxxxxxxx>
AuthorDate: Sun, 25 Apr 2021 23:09:03 +08:00
Committer: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
CommitterDate: Tue, 10 Aug 2021 15:39:00 +02:00

genirq/timings: Prevent potential array overflow in __irq_timings_store()

When the interrupt interval is greater than 2 ^ PREDICTION_BUFFER_SIZE *
PREDICTION_FACTOR us and less than 1s, the calculated index will be greater
than the length of irqs->ema_time[]. Check the calculated index before
using it to prevent array overflow.

Fixes: 23aa3b9a6b7d ("genirq/timings: Encapsulate storing function")
Signed-off-by: Ben Dai <ben.dai@xxxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Link: https://lore.kernel.org/r/20210425150903.25456-1-ben.dai9703@xxxxxxxxx

---
kernel/irq/timings.c | 5 +++++
1 file changed, 5 insertions(+)

diff --git a/kernel/irq/timings.c b/kernel/irq/timings.c
index d309d6f..4d2a702 100644
--- a/kernel/irq/timings.c
+++ b/kernel/irq/timings.c
@@ -453,6 +453,11 @@ static __always_inline void __irq_timings_store(int irq, struct irqt_stat *irqs,
*/
index = irq_timings_interval_index(interval);

+ if (index > PREDICTION_BUFFER_SIZE - 1) {
+ irqs->count = 0;
+ return;
+ }
+
/*
* Store the index as an element of the pattern in another
* circular array.