[llvm] [offload] Do not pool memory while allocation traces are requested (PR #214752)

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llvmorg-github-actions[bot] wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-offload

Author: Robert Imschweiler (ro-i)

<details>
<summary>Changes</summary>

Would otherwise hide use-after-free because memory stays valid if it's in the pool.

---
Full diff: https://github.com/llvm/llvm-project/pull/214752.diff


1 Files Affected:

- (modified) offload/plugins-nextgen/common/src/PluginInterface.cpp (+6-2) 


``````````diff
diff --git a/offload/plugins-nextgen/common/src/PluginInterface.cpp b/offload/plugins-nextgen/common/src/PluginInterface.cpp
index e539cbfc55324..d4f3d8b62a272 100644
--- a/offload/plugins-nextgen/common/src/PluginInterface.cpp
+++ b/offload/plugins-nextgen/common/src/PluginInterface.cpp
@@ -598,9 +598,13 @@ Error GenericDeviceTy::init(GenericPluginTy &Plugin) {
     GridValues.GV_Max_WG_Size =
         std::min(GridValues.GV_Max_WG_Size, uint32_t(OMP_TeamsThreadLimit));
 
-  // Enable the memory manager if required.
+  // Enable the memory manager if required. Memory that the manager pools is
+  // not returned to the driver when it is freed, so a later access to it
+  // neither faults nor is reported by the allocation tracker. Leave the pool
+  // disabled while allocation traces are requested, so that we don't mask
+  // use-after-free (since they don't fault if the memory is still in the pool).
   auto [ThresholdMM, EnableMM] = MemoryManagerTy::getSizeThresholdFromEnv();
-  if (EnableMM) {
+  if (EnableMM && !OMPX_TrackAllocationTraces) {
     if (ThresholdMM == 0)
       ThresholdMM = getMemoryManagerSizeThreshold();
     MemoryManager = new MemoryManagerTy(*this, ThresholdMM);

``````````

</details>


https://github.com/llvm/llvm-project/pull/214752