Prevent memory corruption by StreamId::Set

webrtc/common_types.cc

Index: webrtc/common_types.cc
diff --git a/webrtc/common_types.cc b/webrtc/common_types.cc
index b9c4737aeb511627bd1b3697269ef047d8a11ad1..90709402a1db36e6af12d5b8969bd667e05dd19c 100644
--- a/webrtc/common_types.cc
+++ b/webrtc/common_types.cc
@@ -25,8 +25,8 @@ constexpr size_t StreamId::kMaxSize;
 
 void StreamId::Set(const char* data, size_t size) {
   // If |data| contains \0, the stream id size might become less than |size|.
-  RTC_DCHECK_LE(size, kMaxSize);
-  memcpy(value_, data, size);
+  RTC_CHECK_LE(size, kMaxSize);
+  memcpy(value_, data, std::min(size, kMaxSize));

[danilchap, 2017/06/01 15:42:44]

you shouldn't try to recover after failed CHECK:
CHECK will crash the program, i.e. this line will run only if size <= kMaxSize

[eladalon, 2017/06/01 15:48:43]

As per the CL's description, I'm afraid someone might turn off RTC_CHECKs. Some
third-party apps might turn it off. No?

[danilchap, 2017/06/01 15:54:56]

DCHECKS can be turned off, CHECKS - can't. 
quote from base/checks.h: 
"RTC_CHECK always evaluates its argument, so it's OK for x to have side effects"

[eladalon, 2017/06/01 15:59:48]

Very well; undone.

   if (size < kMaxSize)
     value_[size] = 0;
 }