[flang][unittests] Fix buffer underrun in LengthWithoutTrailingSpaces #84382
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Account for the descriptor containing a zero-length string. Also, avoid iterating backwards too far. This was detected by address sanitizer.
llvmbot
added
flang:runtime
flang
|
@llvm/pr-subscribers-flang-runtime Author: Krzysztof Parzyszek (kparzysz) ChangesAccount for the descriptor containing a zero-length string. Also, avoid iterating backwards too far. This was detected by address sanitizer. Full diff: https://github.com/llvm/llvm-project/pull/84382.diff 1 Files Affected:
diff --git a/flang/runtime/command.cpp b/flang/runtime/command.cpp
index 7c44890545bd3f..141518f324bbcc 100644
--- a/flang/runtime/command.cpp
+++ b/flang/runtime/command.cpp
@@ -196,11 +196,14 @@ std::int32_t RTNAME(GetCommand)(const Descriptor *value,
}
static std::size_t LengthWithoutTrailingSpaces(const Descriptor &d) {
- std::size_t s{d.ElementBytes() - 1};
- while (*d.OffsetElement(s) == ' ') {
+ std::size_t s{d.ElementBytes()}; // This can be 0.
+ if (s == 0) {
+ return 0;
+ }
+ while (s != 0 && *d.OffsetElement(s - 1) == ' ') {
--s;
}
- return s + 1;
+ return s;
}
std::int32_t RTNAME(GetEnvVariable)(const Descriptor &name,
|
klausler
approved these changes
Mar 11, 2024
flang/runtime/command.cpp
Outdated
| std::size_t s{d.ElementBytes() - 1}; | ||
| while (*d.OffsetElement(s) == ' ') { | ||
| std::size_t s{d.ElementBytes()}; // This can be 0. | ||
| if (s == 0) { |
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This if statement is unnecessary.
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Account for the descriptor containing a zero-length string. Also, avoid iterating backwards too far.
This was detected by address sanitizer.