UefiCpuPkg/MpLib: fix potential overflow issue.

Current calculate timeout logic may have overflow if the input
timeout value too large. This patch fix this potential overflow
issue.

V2: Use local variable instead of call GetPerformanceCounterProperties
twice. Also correct some comments.

Cc: Michael Kinney <michael.d.kinney@intel.com>
Cc: Ruiyu Ni <ruiyu.ni@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Eric Dong <eric.dong@intel.com>
Reviewed-by: Michael Kinney <michael.d.kinney@intel.com>

diff --git a/UefiCpuPkg/Library/MpInitLib/MpLib.c b/UefiCpuPkg/Library/MpInitLib/MpLib.c
index ed1f55e955c2eba85fc6709767e8420400388cdb..8394572c6107156779f1b937c4366e5e9480d7e6 100644 (file)
--- a/UefiCpuPkg/Library/MpInitLib/MpLib.c
+++ b/UefiCpuPkg/Library/MpInitLib/MpLib.c
@@ -1001,6 +1001,9 @@ CalculateTimeout (
   OUT UINT64  *CurrentTime\r
   )\r
 {\r
+  UINT64 TimeoutInSeconds;\r
+  UINT64 TimestampCounterFreq;\r
+\r
   //\r
   // Read the current value of the performance counter\r
   //\r
@@ -1016,16 +1019,36 @@ CalculateTimeout (
 \r
   //\r
   // GetPerformanceCounterProperties () returns the timestamp counter's frequency\r
-  // in Hz. So multiply the return value with TimeoutInMicroseconds and then divide\r
-  // it by 1,000,000, to get the number of ticks for the timeout value.\r
-  //\r
-  return DivU64x32 (\r
-           MultU64x64 (\r
-             GetPerformanceCounterProperties (NULL, NULL),\r
-             TimeoutInMicroseconds\r
-             ),\r
-           1000000\r
-           );\r
+  // in Hz. \r
+  //\r
+  TimestampCounterFreq = GetPerformanceCounterProperties (NULL, NULL);\r
+\r
+  //\r
+  // Check the potential overflow before calculate the number of ticks for the timeout value.\r
+  //\r
+  if (DivU64x64Remainder (MAX_UINT64, TimeoutInMicroseconds, NULL) < TimestampCounterFreq) {\r
+    //\r
+    // Convert microseconds into seconds if direct multiplication overflows\r
+    //\r
+    TimeoutInSeconds = DivU64x32 (TimeoutInMicroseconds, 1000000);\r
+    //\r
+    // Assertion if the final tick count exceeds MAX_UINT64\r
+    //\r
+    ASSERT (DivU64x64Remainder (MAX_UINT64, TimeoutInSeconds, NULL) >= TimestampCounterFreq);\r
+    return MultU64x64 (TimestampCounterFreq, TimeoutInSeconds);\r
+  } else {\r
+    //\r
+    // No overflow case, multiply the return value with TimeoutInMicroseconds and then divide\r
+    // it by 1,000,000, to get the number of ticks for the timeout value.\r
+    //\r
+    return DivU64x32 (\r
+             MultU64x64 (\r
+               TimestampCounterFreq,\r
+               TimeoutInMicroseconds\r
+               ),\r
+             1000000\r
+             );\r
+  }\r
 }\r
 \r
 /**\r