[compiler-rt] [scudo] Update error handling for cache entry count in secondary cach… (PR #95595)

[via llvm-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-compiler-rt-sanitizer

Author: Joshua Baehring (JoshuaMBa)

<details>
<summary>Changes</summary>

…e option handler.

Initially, the scudo allocator would return an error if the user attempted to set the cache capacity (i.e. the number of possible entries in the cache) above the maximum cache capacity. Now the allocator will resort to using the maximum cache capacity in this event. An error will still be returned if the user attempts to set the number of entries to a negative value.

---
Full diff: https://github.com/llvm/llvm-project/pull/95595.diff


2 Files Affected:

- (modified) compiler-rt/lib/scudo/standalone/secondary.h (+4-4) 
- (modified) compiler-rt/lib/scudo/standalone/tests/secondary_test.cpp (+3-3) 


``````````diff
diff --git a/compiler-rt/lib/scudo/standalone/secondary.h b/compiler-rt/lib/scudo/standalone/secondary.h
index d8c9f5bcfcaf6..0e0788f830431 100644
--- a/compiler-rt/lib/scudo/standalone/secondary.h
+++ b/compiler-rt/lib/scudo/standalone/secondary.h
@@ -391,10 +391,10 @@ template <typename Config> class MapAllocatorCache {
       return true;
     }
     if (O == Option::MaxCacheEntriesCount) {
-      const u32 MaxCount = static_cast<u32>(Value);
-      if (MaxCount > Config::getEntriesArraySize())
-        return false;
-      atomic_store_relaxed(&MaxEntriesCount, MaxCount);
+      if (Value < 0) return false;
+      atomic_store_relaxed(
+          &MaxEntriesCount,
+          Min<u32>(static_cast<u32>(Value), Config::getEntriesArraySize()));
       return true;
     }
     if (O == Option::MaxCacheEntrySize) {
diff --git a/compiler-rt/lib/scudo/standalone/tests/secondary_test.cpp b/compiler-rt/lib/scudo/standalone/tests/secondary_test.cpp
index 8f0250e88ebf3..af69313214ea6 100644
--- a/compiler-rt/lib/scudo/standalone/tests/secondary_test.cpp
+++ b/compiler-rt/lib/scudo/standalone/tests/secondary_test.cpp
@@ -192,9 +192,9 @@ TEST_F(MapAllocatorTest, SecondaryIterate) {
 
 TEST_F(MapAllocatorTest, SecondaryOptions) {
   // Attempt to set a maximum number of entries higher than the array size.
-  EXPECT_FALSE(
-      Allocator->setOption(scudo::Option::MaxCacheEntriesCount, 4096U));
-  // A negative number will be cast to a scudo::u32, and fail.
+  EXPECT_TRUE(Allocator->setOption(scudo::Option::MaxCacheEntriesCount, 4096U));
+
+  // Attempt to set an invalid (negative) number of entries
   EXPECT_FALSE(Allocator->setOption(scudo::Option::MaxCacheEntriesCount, -1));
   if (Allocator->canCache(0U)) {
     // Various valid combinations.

``````````

</details>


https://github.com/llvm/llvm-project/pull/95595