ARM: 6654/1: perf/oprofile: fix off-by-one in stack check
Since tail is the previous fp - 1, we need to compare the new fp with tail + 1
to ensure that we don't end up passing in the same tail again, in order to
avoid a potential infinite loop in the perf interrupt handler (which has been
observed to occur). A similar fix seems to be needed in the OProfile code.
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Rabin Vincent <rabin.vincent@stericsson.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
diff --git a/arch/arm/kernel/perf_event.c b/arch/arm/kernel/perf_event.c
index 5efa264..d150ad1 100644
--- a/arch/arm/kernel/perf_event.c
+++ b/arch/arm/kernel/perf_event.c
@@ -700,7 +700,7 @@
* Frame pointers should strictly progress back up the stack
* (towards higher addresses).
*/
- if (tail >= buftail.fp)
+ if (tail + 1 >= buftail.fp)
return NULL;
return buftail.fp - 1;
diff --git a/arch/arm/oprofile/common.c b/arch/arm/oprofile/common.c
index 8aa9744..6adda2b 100644
--- a/arch/arm/oprofile/common.c
+++ b/arch/arm/oprofile/common.c
@@ -85,7 +85,7 @@
/* frame pointers should strictly progress back up the stack
* (towards higher addresses) */
- if (tail >= buftail[0].fp)
+ if (tail + 1 >= buftail[0].fp)
return NULL;
return buftail[0].fp-1;