Timm =?utf-8?q?Bäder?= <[email protected]> Message-ID: <llvm.org/llvm/llvm-project/pull/[email protected]> In-Reply-To:
https://github.com/tbaederr created https://github.com/llvm/llvm-project/pull/174187 We can't read from them and this fails later. Fixes https://github.com/llvm/llvm-project/issues/173942 >From cecb72441ee0e2886deb8f058d7a59f770430fb1 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Timm=20B=C3=A4der?= <[email protected]> Date: Fri, 2 Jan 2026 09:10:48 +0100 Subject: [PATCH 1/2] [clang][bytecode] Check builtin_memcpy() for non-block pointers This pretty hard to produce in C++ but easy in C. Fixes #171609 --- clang/lib/AST/ByteCode/InterpBuiltin.cpp | 15 +++++++++++++-- clang/test/AST/ByteCode/builtins.c | 1 + 2 files changed, 14 insertions(+), 2 deletions(-) diff --git a/clang/lib/AST/ByteCode/InterpBuiltin.cpp b/clang/lib/AST/ByteCode/InterpBuiltin.cpp index 57d5f0ae6eed3..65101174247d1 100644 --- a/clang/lib/AST/ByteCode/InterpBuiltin.cpp +++ b/clang/lib/AST/ByteCode/InterpBuiltin.cpp @@ -64,6 +64,18 @@ static APSInt popToAPSInt(InterpState &S, QualType T) { return popToAPSInt(S.Stk, *S.getContext().classify(T)); } +/// Check for common reasons a pointer can't be read from, which +/// are usually not diagnosed in a builtin function. +static bool isReadable(const Pointer &P) { + if (P.isDummy()) + return false; + if (!P.isBlockPointer()) + return false; + if (!P.isLive()) + return false; + return true; +} + /// Pushes \p Val on the stack as the type given by \p QT. static void pushInteger(InterpState &S, const APSInt &Val, QualType QT) { assert(QT->isSignedIntegerOrEnumerationType() || @@ -1794,8 +1806,7 @@ static bool interp__builtin_memcpy(InterpState &S, CodePtr OpPC, return false; } - // Can't read from dummy pointers. - if (DestPtr.isDummy() || SrcPtr.isDummy()) + if (!isReadable(DestPtr) || !isReadable(SrcPtr)) return false; if (DestPtr.getType()->isIncompleteType()) { diff --git a/clang/test/AST/ByteCode/builtins.c b/clang/test/AST/ByteCode/builtins.c index a51260cd3431f..5be5455ab8813 100644 --- a/clang/test/AST/ByteCode/builtins.c +++ b/clang/test/AST/ByteCode/builtins.c @@ -17,3 +17,4 @@ int structStrlen(void) { return 1; } +void f() { __builtin_memcpy(f, f, 1); } >From c5959f99134048776518030054bfbe9cceaa1c18 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Timm=20B=C3=A4der?= <[email protected]> Date: Fri, 2 Jan 2026 09:29:56 +0100 Subject: [PATCH 2/2] [clang][bytecode] Check builtin_memchr() for one-past-end pointers We can't read from them and this fails later. Fixes #173942 --- clang/lib/AST/ByteCode/InterpBuiltin.cpp | 5 +++++ clang/test/AST/ByteCode/builtin-functions.cpp | 4 ++++ 2 files changed, 9 insertions(+) diff --git a/clang/lib/AST/ByteCode/InterpBuiltin.cpp b/clang/lib/AST/ByteCode/InterpBuiltin.cpp index 65101174247d1..065870c5c0ab5 100644 --- a/clang/lib/AST/ByteCode/InterpBuiltin.cpp +++ b/clang/lib/AST/ByteCode/InterpBuiltin.cpp @@ -73,6 +73,8 @@ static bool isReadable(const Pointer &P) { return false; if (!P.isLive()) return false; + if (P.isOnePastEnd()) + return false; return true; } @@ -2089,6 +2091,9 @@ static bool interp__builtin_memchr(InterpState &S, CodePtr OpPC, return false; } + if (!isReadable(Ptr)) + return false; + if (ID == Builtin::BIstrchr || ID == Builtin::BI__builtin_strchr) { int64_t DesiredTrunc; if (S.getASTContext().CharTy->isSignedIntegerType()) diff --git a/clang/test/AST/ByteCode/builtin-functions.cpp b/clang/test/AST/ByteCode/builtin-functions.cpp index 3076b5239ebbe..3cde5a2b42e3d 100644 --- a/clang/test/AST/ByteCode/builtin-functions.cpp +++ b/clang/test/AST/ByteCode/builtin-functions.cpp @@ -1649,6 +1649,10 @@ namespace Memchr { return __builtin_char_memchr(c + 1, 'f', 1) == nullptr; } static_assert(f()); + + + extern const char char_memchr_arg[0l]; + char *memchr_result = __builtin_char_memchr(char_memchr_arg, 123, 32); } namespace Strchr { _______________________________________________ cfe-commits mailing list [email protected] https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
