[compiler-rt] [scudo] Add an option to zero memory on deallocation. (PR #142394)

[via llvm-commits]

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@@ -1345,6 +1352,19 @@ class Allocator {
         BlockBegin = retagBlock(Options, TaggedPtr, Ptr, Header, Size, true);
       }
 
+#ifdef SCUDO_FUCHSIA
+      if (AllocatorConfig::getEnableZeroOnDealloc()) {
+        // Clearing the header and is incompatible with quarantine and tagging.
+        // Hence, it is fine to implement it only when quanrantine is bypassed.
+        DCHECK(!useMemoryTagging<AllocatorConfig>(Options));
+        uptr length = reinterpret_cast<uptr>(Ptr) + Size -
+                      reinterpret_cast<uptr>(BlockBegin);
+        if (length <= ZeroOnDeallocMaxSize) {
+          memset(BlockBegin, 0, length);
+        }
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piwicode wrote:

Done.

https://github.com/llvm/llvm-project/pull/142394