[PATCH 3.19 039/101] powerpc: fix memory corruption by pnv_alloc_idle_core_states

[Greg Kroah-Hartman]

3.19-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Jan Stancek <jstancek@xxxxxxxxxx>

commit d52356e7f48e400ca258c6763a232a92fa82ff68 upstream.

Space allocated for paca is based off nr_cpu_ids,
but pnv_alloc_idle_core_states() iterates paca with
cpu_nr_cores()*threads_per_core, which is using NR_CPUS.

This causes pnv_alloc_idle_core_states() to write over memory,
which is outside of paca array and may later lead to various panics.

Fixes: 7cba160ad789 (powernv/cpuidle: Redesign idle states management)
Signed-off-by: Jan Stancek <jstancek@xxxxxxxxxx>
Signed-off-by: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Signed-off-by: Preet U. Murthy <preeti@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 arch/powerpc/include/asm/cputhreads.h |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/arch/powerpc/include/asm/cputhreads.h
+++ b/arch/powerpc/include/asm/cputhreads.h
@@ -55,7 +55,7 @@ static inline cpumask_t cpu_thread_mask_
 
 static inline int cpu_nr_cores(void)
 {
-	return NR_CPUS >> threads_shift;
+	return nr_cpu_ids >> threads_shift;
 }
 
 static inline cpumask_t cpu_online_cores_map(void)


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