[PATCH 5.13 126/151] genirq/timings: Prevent potential array overflow in __irq_timings_store()

Greg Kroah-Hartman
2021-08-16T13:30:03Z

From: Ben Dai <ben.dai@unisoc.com>

commit b9cc7d8a4656a6e815852c27ab50365009cb69c1 upstream.

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@unisoc.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20210425150903.25456-1-ben.dai9703@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
kernel/irq/timings.c | 5 +++++
1 file changed, 5 insertions(+)

--- a/kernel/irq/timings.c
+++ b/kernel/irq/timings.c
@@ -453,6 +453,11 @@ static __always_inline void __irq_timing
*/
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.