[PATCH 5.12 303/700] perf/arm-cmn: Fix invalid pointer when access dtc object sharing the same IRQ number

From: Greg Kroah-Hartman
Date: Mon Jul 12 2021 - 03:40:42 EST


From: Tuan Phan <tuanphan@xxxxxxxxxxxxxxxxxxxxxx>

[ Upstream commit 4e16f283edc289820e9b2d6f617ed8e514ee8396 ]

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@xxxxxxxxxxxxxxxxxxxxxx>
Reviewed-by: Robin Murphy <robin.murphy@xxxxxxx>
Link: https://lore.kernel.org/r/1623946129-3290-1-git-send-email-tuanphan@xxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Will Deacon <will@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
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 1328159fe564..a4339426664e 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;
}
}
--
2.30.2