[compiler-rt] [msan] Mark allocator padding as uninitialized, with new origin tag (PR #157187)

[Florian Mayer via llvm-commits]

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@@ -22,6 +22,7 @@ MSAN_FLAG(int, origin_history_size, Origin::kMaxDepth, "")
 MSAN_FLAG(int, origin_history_per_stack_limit, 20000, "")
 MSAN_FLAG(bool, poison_heap_with_zeroes, false, "")
 MSAN_FLAG(bool, poison_stack_with_zeroes, false, "")
+MSAN_FLAG(bool, poison_in_calloc, true, "")
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fmayer wrote:

*everything* shares this flag (malloc, realloc, valloc, aligned_alloc, memalign, posix_memalign), which means it means "poison in alloc" essentially. IMO adding a new flag adds more confusion, not less.

https://github.com/llvm/llvm-project/pull/157187