[PATCH] powerpc: handle error case in cpm_muram_alloc()

[Christophe Leroy]

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 at c-s.fr>
---
 arch/powerpc/sysdev/cpm_common.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/sysdev/cpm_common.c b/arch/powerpc/sysdev/cpm_common.c
index e2ea519..e00a5ee 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;
-- 
2.1.0