[Patch 3/4] CryptoPkg/BaseCryptLib: Adding NULL checking in timer() wrapper.

[Qin Long <qin.long@intel.com>]

There are some explicit timer(NULL) calls in openssl-1.1.0xx source,
but the dummy timer() wrapper in ConstantTimeClock.c (used by PEI
and SMM module) has no any checks on NULL parameter. This will
cause the memory access issue.
This patch adds the NULL parameter checking in timer() wrapper.

Cc: Ting Ye <ting.ye@intel.com>
Cc: Eric Dong <eric.dong@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Qin Long <qin.long@intel.com>
---
 CryptoPkg/Library/BaseCryptLib/SysCall/ConstantTimeClock.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/CryptoPkg/Library/BaseCryptLib/SysCall/ConstantTimeClock.c b/CryptoPkg/Library/BaseCryptLib/SysCall/ConstantTimeClock.c
index 7f20164999..0cd90434ca 100644
--- a/CryptoPkg/Library/BaseCryptLib/SysCall/ConstantTimeClock.c
+++ b/CryptoPkg/Library/BaseCryptLib/SysCall/ConstantTimeClock.c
@@ -31,8 +31,10 @@ WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
 
 time_t time (time_t *timer)
 {
-  *timer = 0;
-  return *timer;
+  if (timer != NULL) {
+    *timer = 0;
+  }
+  return 0;
 }
 
 struct tm * gmtime (const time_t *timer)
-- 
2.12.2.windows.1