powerpc: handle error case in cpm_muram_alloc()

rh_alloc() returns (unsigned long)-ERRxx on error, which may
result in overwriting memory outside the MURAM AREA.

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Scott Wood <scottwood@freescale.com>

1 files changed, 2 insertions, 1 deletions

diff --git a/arch/powerpc/sysdev/cpm_common.c b/arch/powerpc/sysdev/cpm_common.c
index e2ea51961979..e00a5ee58fd7 100644
--- a/arch/powerpc/sysdev/cpm_common.c
+++ b/arch/powerpc/sysdev/cpm_common.c
@@ -147,7 +147,8 @@ unsigned long cpm_muram_alloc(unsigned long size, unsigned long align)
         spin_lock_irqsave(&cpm_muram_lock, flags);
         cpm_muram_info.alignment = align;
         start = rh_alloc(&cpm_muram_info, size, "commproc");
-        memset_io(cpm_muram_addr(start), 0, size);
+        if (!IS_ERR_VALUE(start))
+                memset_io(cpm_muram_addr(start), 0, size);
         spin_unlock_irqrestore(&cpm_muram_lock, flags);
 
         return start;