Add LibCallEnumName to RuntimeLibcallImpl. - #3
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…long encodings (llvm#205907) When a (signed or unsigned) LEB128 value is encoded with extra trailing bytes that only carry zero- or sign-extension, the decode loop could keep running with the shift amount at 64 or beyond and then evaluate `Slice << Shift`, which is undefined behavior for a 64-bit type. The DWARF expression parser feeds attacker-controlled LEB128 operands (such as `DW_OP_bregN` / `DW_OP_constu`) through `DataExtractor::getULEB128` / `getSLEB128`, so the `lldb-dwarf-expression-fuzzer` reaches this under UBSan. The unsigned case: ``` LEB128.h:152:20: runtime error: shift exponent 70 is too large for 64-bit type 'uint64_t' (aka 'unsigned long long') #0 llvm::decodeULEB128(...) LEB128.h:152 #1 getLEB128<unsigned long long>(...) DataExtractor.cpp:227 #2 llvm::DataExtractor::getULEB128(...) DataExtractor.cpp:241 #3 llvm::DWARFExpression::Operation::extract(...) DWARFExpression.cpp:218 llvm#7 lldb_private::DWARFExpression::Evaluate(...) DWARFExpression.cpp:1333 llvm#9 LLVMFuzzerTestOneInput lldb-dwarf-expression-fuzzer.cpp:83 SUMMARY: UndefinedBehaviorSanitizer: undefined-behavior LEB128.h:152:20 ``` and the signed case, reached the same way: ``` LEB128.h:190:20: runtime error: shift exponent 70 is too large for 64-bit type 'uint64_t' (aka 'unsigned long long') #0 llvm::decodeSLEB128(...) LEB128.h:190 #1 getLEB128<long long>(...) DataExtractor.cpp:227 #2 llvm::DataExtractor::getSLEB128(...) DataExtractor.cpp:245 #3 llvm::DWARFExpression::Operation::extract(...) DWARFExpression.cpp:216 llvm#7 lldb_private::DWARFExpression::Evaluate(...) DWARFExpression.cpp:1333 ``` The existing range checks already guarantee that once `Shift` reaches 64 the remaining bytes are pure extension and contribute nothing to the result, so skip the accumulating shift in that case. Decoded values are unchanged for all well-formed inputs. Adds overlong-encoding regression cases to `LEB128Test`. Without the fix the signed case is the UBSan diagnostic above in a sanitizer build, and in a normal build the unsigned case also decodes to the wrong value (the overlong `1` decodes as `11`).
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