Security: Replace dac_mmap_min_addr to mmap_min_addr in cap_file_mmap()

[wzt.wzt@gmail.com]

cap_file_mmap() comments said "If the process is attempting to map 
memory below mmap_min_addr", if CONFIG_LSM_MMAP_MIN_ADDR is set, 
dac_mmap_min_addr is not equal mmap_min_addr, so replace dac_mmap_min_addr
to mmap_min_addr seems to be better.

Signed-off-by: Zhitong Wang <zhitong.wangzt@alibaba-inc.com>

---
 include/linux/security.h |    1 +
 security/commoncap.c     |    2 +-
 2 files changed, 2 insertions(+), 1 deletions(-)

diff --git a/include/linux/security.h b/include/linux/security.h
index 233d20b..61fd9e7 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -101,6 +101,7 @@ void reset_security_ops(void);
 extern unsigned long mmap_min_addr;
 extern unsigned long dac_mmap_min_addr;
 #else
+#define mmap_min_addr		0UL
 #define dac_mmap_min_addr	0UL
 #endif
 
diff --git a/security/commoncap.c b/security/commoncap.c
index 6166973..878cf89 100644
--- a/security/commoncap.c
+++ b/security/commoncap.c
@@ -942,7 +942,7 @@ int cap_file_mmap(struct file *file, unsigned long reqprot,
 {
 	int ret = 0;
 
-	if (addr < dac_mmap_min_addr) {
+	if (addr < mmap_min_addr) {
 		ret = cap_capable(current, current_cred(), CAP_SYS_RAWIO,
 				  SECURITY_CAP_AUDIT);
 		/* set PF_SUPERPRIV if it turns out we allow the low mmap */
-- 
1.6.5.3