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ARM: 6654/1: perf/oprofile: fix off-by-one in stack check

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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>
This commit is contained in:
Rabin Vincent 2011-02-09 11:35:12 +01:00 committed by Russell King
parent 4a9cb36019
commit cb06199b1d
2 changed files with 2 additions and 2 deletions
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2
arch/arm/kernel/perf_event.c
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@ -700,7 +700,7 @@ user_backtrace(struct frame_tail __user *tail,
* Frame pointers should strictly progress back up the stack * Frame pointers should strictly progress back up the stack
* (towards higher addresses). * (towards higher addresses).
*/ */
if (tail >= buftail.fp) if (tail + 1 >= buftail.fp)
return NULL; return NULL;
return buftail.fp - 1; return buftail.fp - 1;

2
arch/arm/oprofile/common.c
View File

@ -85,7 +85,7 @@ static struct frame_tail* user_backtrace(struct frame_tail *tail)
/* frame pointers should strictly progress back up the stack /* frame pointers should strictly progress back up the stack
* (towards higher addresses) */ * (towards higher addresses) */
if (tail >= buftail[0].fp) if (tail + 1 >= buftail[0].fp)
return NULL; return NULL;
return buftail[0].fp-1; return buftail[0].fp-1;