[PATCH] powerpc/papr_scm: Make access mode of 'perf_stats' attribute file to '0400'

The newly introduced 'perf_stats' attribute uses the default access
mode of 0444 letting non-root users access performance stats of an
nvdimm and potentially force the kernel into issuing large number of
expensive HCALLs. Since the information exposed by this attribute
cannot be cached hence its better to ward of access to this attribute
from non-root users.

Hence this patch updates the access-mode of 'perf_stats' sysfs
attribute file to 0400 to make it only readable to root-users.

Reported-by: Aneesh Kumar K.V <redacted>
Signed-off-by: Vaibhav Jain <redacted>
---
 arch/powerpc/platforms/pseries/papr_scm.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/powerpc/platforms/pseries/papr_scm.c b/arch/powerpc/platforms/pseries/papr_scm.c
index f439f0dfea7d1..31864d167a2ce 100644
--- a/arch/powerpc/platforms/pseries/papr_scm.c
+++ b/arch/powerpc/platforms/pseries/papr_scm.c

@@ -822,7 +822,7 @@ static ssize_t perf_stats_show(struct device *dev,
 	kfree(stats);
 	return rc ? rc : seq_buf_used(&s);
 }
-DEVICE_ATTR_RO(perf_stats);
+DEVICE_ATTR(perf_stats, 0400, perf_stats_show, NULL);
 
 static ssize_t flags_show(struct device *dev,
 			  struct device_attribute *attr, char *buf)

-- 
2.26.2