https://llvm.org/bugs/show_bug.cgi?id=30478
Bug ID: 30478 Summary: UBSan vptr: false positive if virtual method if privately overriden Product: new-bugs Version: trunk Hardware: PC OS: Linux Status: NEW Severity: normal Priority: P Component: new bugs Assignee: unassignedb...@nondot.org Reporter: kra...@google.com CC: llvm-bugs@lists.llvm.org Classification: Unclassified Created attachment 17329 --> https://llvm.org/bugs/attachment.cgi?id=17329&action=edit many_bases.cc Based on the analysis of a Chromium test failure that feels like a false positive from UBSan's vptr check, I have come up with the following minimal reproducer: many_bases.cc (also attached): #include <stdio.h> class Base1 { public: virtual void Do() { printf("Base1::Do\n"); } }; class Base2 { public: virtual void Do2() { printf("Base2::Do2\n"); } }; class Derived final : public Base1, public Base2 { private: void Do2() override { printf("Derived::Do2\n"); } }; int main(void) { Derived obj; static_cast<Base2*>(&obj)->Do2(); } Compiling and running: $ clang++ -o many_bases many_bases.cc -fsanitize=vptr -fno-sanitize-recover=undefined -fvisibility=hidden -std=gnu++11 && ./many_bases many_bases.cc:20:30: runtime error: member call on address 0x7ffe64429bb8 which does not point to an object of type 'Base2' 0x7ffe64429bb8: note: object is of type 'Derived' ea 46 63 ba c0 ee 42 00 00 00 00 00 e0 ee 42 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ^~~~~~~~~~~~~~~~~~~~~~~ vptr for 'Derived' The error message does not make sense to me. -- You are receiving this mail because: You are on the CC list for the bug.
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