From 27398d6632d34df8fd723c2f84d4eaabb2890d1e Mon Sep 17 00:00:00 2001
From: Dan Minor <dminor@webrtc.org>
Date: Wed, 1 Jul 2020 12:16:16 -0400
Subject: [PATCH] Prevent undefined shift in TimestampWrapAroundHandler::Unwrap

If num_wrap_ is zero this will result in a left shift of a
negative number, which is undefined behaviour.

Bug: webrtc:11742
Change-Id: I4a6ac448c5af82e15beb25ed55c16bab26e6ee5f
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/178441
Commit-Queue: Dan Minor <dminor@webrtc.org>
Reviewed-by: Karl Wiberg <kwiberg@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#31608}
---
 rtc_base/time_utils.cc | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/rtc_base/time_utils.cc b/rtc_base/time_utils.cc
index 8d919262d3..11c9d5a47f 100644
--- a/rtc_base/time_utils.cc
+++ b/rtc_base/time_utils.cc
@@ -247,7 +247,7 @@ int64_t TimestampWrapAroundHandler::Unwrap(uint32_t ts) {
       ++num_wrap_;
   } else if ((ts - last_ts_) > 0xf0000000) {
     // Backwards wrap. Unwrap with last wrap count and don't update last_ts_.
-    return ts + ((num_wrap_ - 1) << 32);
+    return ts + (num_wrap_ - 1) * (int64_t{1} << 32);
   }
 
   last_ts_ = ts;