[PATCH] perf/arm-cmn: Fix invalid pointer when access dtc object sharing the same IRQ number

[PATCH] perf/arm-cmn: Fix invalid pointer when access dtc object sharing the same IRQ number

[Tuan Phan]

When multiple dtcs share the same IRQ number, the irq_friend which
used to refer to dtc object gets calculated incorrect which leads
to invalid pointer.

Fixes: 0ba64770a2f2 ("perf: Add Arm CMN-600 PMU driver")

Signed-off-by: Tuan Phan <tuanphan@os.amperecomputing.com>
---
 drivers/perf/arm-cmn.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/perf/arm-cmn.c b/drivers/perf/arm-cmn.c
index 56a5c35..49016f2 100644
--- a/drivers/perf/arm-cmn.c
+++ b/drivers/perf/arm-cmn.c
@@ -1212,7 +1212,7 @@ static int arm_cmn_init_irqs(struct arm_cmn *cmn)
 		irq = cmn->dtc[i].irq;
 		for (j = i; j--; ) {
 			if (cmn->dtc[j].irq == irq) {
-				cmn->dtc[j].irq_friend = j - i;
+				cmn->dtc[j].irq_friend = i - j;
 				goto next;
 			}
 		}
-- 
2.7.4

Re: [PATCH] perf/arm-cmn: Fix invalid pointer when access dtc object sharing the same IRQ number

[Robin Murphy]

On 2021-06-17 17:08, Tuan Phan wrote:
> When multiple dtcs share the same IRQ number, the irq_friend which
> used to refer to dtc object gets calculated incorrect which leads
> to invalid pointer.

Oops, indeed this is supposed to be a forward offset *from* the previous 
match *to* the current dtc. It's almost as if I never managed to test 
it... :)

Reviewed-by: Robin Murphy <robin.murphy@arm.com>

> Fixes: 0ba64770a2f2 ("perf: Add Arm CMN-600 PMU driver")
> 
> Signed-off-by: Tuan Phan <tuanphan@os.amperecomputing.com>
> ---
>   drivers/perf/arm-cmn.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/perf/arm-cmn.c b/drivers/perf/arm-cmn.c
> index 56a5c35..49016f2 100644
> --- a/drivers/perf/arm-cmn.c
> +++ b/drivers/perf/arm-cmn.c
> @@ -1212,7 +1212,7 @@ static int arm_cmn_init_irqs(struct arm_cmn *cmn)
>   		irq = cmn->dtc[i].irq;
>   		for (j = i; j--; ) {
>   			if (cmn->dtc[j].irq == irq) {
> -				cmn->dtc[j].irq_friend = j - i;
> +				cmn->dtc[j].irq_friend = i - j;
>   				goto next;
>   			}
>   		}
> 

Re: [PATCH] perf/arm-cmn: Fix invalid pointer when access dtc object sharing the same IRQ number

[Will Deacon]

On Thu, 17 Jun 2021 09:08:49 -0700, Tuan Phan wrote:
> When multiple dtcs share the same IRQ number, the irq_friend which
> used to refer to dtc object gets calculated incorrect which leads
> to invalid pointer.
> 
> Fixes: 0ba64770a2f2 ("perf: Add Arm CMN-600 PMU driver")

Applied to will (for-next/perf), thanks!

[1/1] perf/arm-cmn: Fix invalid pointer when access dtc object sharing the same IRQ number
      https://git.kernel.org/will/c/4e16f283edc2

Cheers,
-- 
Will

https://fixes.arm64.dev
https://next.arm64.dev
https://will.arm64.dev