| commit | acaf403c6397dc0fcd8f0988bd057b4d5ee2460f | [log] [tgz] |
|---|---|---|
| author | Krzysztof Pszeniczny <kpszeniczny@google.com> | Mon Apr 28 19:28:56 2025 +0200 |
| committer | GitHub <noreply@github.com> | Mon Apr 28 19:28:56 2025 +0200 |
| tree | 55045b3f95ee8e6c1deda6344009937072a4093f | |
| parent | 4e4c6d7e273a91d230389b98c280c9dbde0f6c32 [diff] |
[SampleProfile] Fix UB in Demangler invocation. (#137659) Currently the backing buffer of a `std::vector<char>` is passed[1] to `Demangler.getFunctionBaseName`. However, deeply inside the call stack `OutputBuffer::grow` will call[2] `std::realloc` if it needs to grow the buffer, leading to UB. The demangler APIs specify[3] that "`Buf` and `N` behave like the second and third parameters to `__cxa_demangle`" and the docs for the latter say[4] that the output buffer must be allocated with `malloc` (but can also be `NULL` and will then be realloced accordingly). Note: PR #135863 changed this from a stack array to a `std::vector` and increased the size to 65K, but this can still lead to a crash if the demangled name is longer than that - yes, I'm surprised that a >65K-long function name happens in practice... [1]: https://github.com/llvm/llvm-project/blob/d7e631c7cd6d9c13b9519991ec6becf08bc6b8aa/llvm/lib/Transforms/IPO/SampleProfileMatcher.cpp#L744 [2]: https://github.com/llvm/llvm-project/blob/d7e631c7cd6d9c13b9519991ec6becf08bc6b8aa/llvm/include/llvm/Demangle/Utility.h#L50 [3]: https://github.com/llvm/llvm-project/blob/d7e631c7cd6d9c13b9519991ec6becf08bc6b8aa/llvm/include/llvm/Demangle/Demangle.h#L92-L93 [4]: https://gcc.gnu.org/onlinedocs/libstdc++/libstdc++-html-USERS-4.3/a01696.html
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