commit d336ebdea812c4c260c2d10bb5a515b7a98a42c1
author Greg Kaiser <gkaiser@google.com> Sun Feb 10 17:51:42 2019 -0800
committer Skia Commit-Bot <skia-commit-bot@chromium.org> Mon Feb 11 10:01:27 2019 +0000
tree cc71df1180d7877860adc692b158d2fca7752531
parent 9be246ed747fd1b900013dd0596aed0b1a63a1fa

SkDeque: Move asserts prior to pointer dereference

If we popped too far, we want the assert mechanism to catch this
bug prior to us dereferencing a nullptr.

Change-Id: I681e530e8bcc15897bc52b3688d83f85a59d7449
Reviewed-on: https://skia-review.googlesource.com/c/191065
Reviewed-by: Mike Klein <mtklein@google.com>
Commit-Queue: Mike Klein <mtklein@google.com>

src/core/SkDeque.cpp

diff --git a/src/core/SkDeque.cpp b/src/core/SkDeque.cpp
index 167ce46..d772a4f 100644
--- a/src/core/SkDeque.cpp
+++ b/src/core/SkDeque.cpp
@@ -157,10 +157,10 @@
 
     if (first->fBegin == nullptr) {  // we were marked empty from before
         first = first->fNext;
+        SkASSERT(first != nullptr);    // else we popped too far
         first->fPrev = nullptr;
         this->freeBlock(fFrontBlock);
         fFrontBlock = first;
-        SkASSERT(first != nullptr);    // else we popped too far
     }
 
     char* begin = first->fBegin + fElemSize;
@@ -191,10 +191,10 @@
 
     if (last->fEnd == nullptr) {  // we were marked empty from before
         last = last->fPrev;
+        SkASSERT(last != nullptr);  // else we popped too far
         last->fNext = nullptr;
         this->freeBlock(fBackBlock);
         fBackBlock = last;
-        SkASSERT(last != nullptr);  // else we popped too far
     }
 
     char* end = last->fEnd - fElemSize;