https://github.com/nataliakokoromyti created https://github.com/llvm/llvm-project/pull/175415
When an asm goto statement references an undeclared label and there's a variable with __attribute__((cleanup)) in scope, clang would crash with a segmentation fault. The issue was that DiagnoseIndirectOrAsmJumpStmt() called Target->getStmt()->getIdentLoc() without checking if getStmt() returns null. For undeclared labels, the LabelDecl exists but has no associated LabelStmt. This patch adds a null check and falls back to Target->getLocation() when the statement is null. Fixes #175314 >From 9af9ed3356707a501b658308f4cd695746874f49 Mon Sep 17 00:00:00 2001 From: Natalia Kokoromyti <[email protected]> Date: Sat, 10 Jan 2026 21:54:11 -0800 Subject: [PATCH] [Sema] Fix crash in asm goto with undeclared label When an asm goto statement references an undeclared label and there's a variable with __attribute__((cleanup)) in scope, clang would crash with a segmentation fault. The issue was that DiagnoseIndirectOrAsmJumpStmt() called Target->getStmt()->getIdentLoc() without checking if getStmt() returns null. For undeclared labels, the LabelDecl exists but has no associated LabelStmt. This patch adds a null check and falls back to Target->getLocation() when the statement is null. Fixes #175314 --- clang/lib/Sema/JumpDiagnostics.cpp | 7 +++++-- clang/test/Sema/asm-goto-undeclared-label-crash.c | 12 ++++++++++++ 2 files changed, 17 insertions(+), 2 deletions(-) create mode 100644 clang/test/Sema/asm-goto-undeclared-label-crash.c diff --git a/clang/lib/Sema/JumpDiagnostics.cpp b/clang/lib/Sema/JumpDiagnostics.cpp index 36c9d9afb37f1..b630559c2db2c 100644 --- a/clang/lib/Sema/JumpDiagnostics.cpp +++ b/clang/lib/Sema/JumpDiagnostics.cpp @@ -914,8 +914,11 @@ static void DiagnoseIndirectOrAsmJumpStmt(Sema &S, Stmt *Jump, bool IsAsmGoto = isa<GCCAsmStmt>(Jump); S.Diag(Jump->getBeginLoc(), diag::err_indirect_goto_in_protected_scope) << IsAsmGoto; - S.Diag(Target->getStmt()->getIdentLoc(), diag::note_indirect_goto_target) - << IsAsmGoto; + // Target->getStmt() can be null for undeclared labels. + SourceLocation TargetLoc = Target->getStmt() + ? Target->getStmt()->getIdentLoc() + : Target->getLocation(); + S.Diag(TargetLoc, diag::note_indirect_goto_target) << IsAsmGoto; Diagnosed = true; } diff --git a/clang/test/Sema/asm-goto-undeclared-label-crash.c b/clang/test/Sema/asm-goto-undeclared-label-crash.c new file mode 100644 index 0000000000000..8538144a87a7d --- /dev/null +++ b/clang/test/Sema/asm-goto-undeclared-label-crash.c @@ -0,0 +1,12 @@ +// RUN: %clang_cc1 -fsyntax-only -verify %s + +// Test that we don't crash when an asm goto references an undeclared label +// and there's a variable with __attribute__((cleanup)) in scope. +// See: https://github.com/llvm/llvm-project/issues/175314 + +void a(int *b) { + int __attribute__((cleanup(a))) c = 0; // expected-note {{jump exits scope of variable with __attribute__((cleanup))}} + __asm__ goto("" : : : : d); // expected-error {{use of undeclared label 'd'}} \ + // expected-error {{cannot jump from this asm goto statement to one of its possible targets}} \ + // expected-note {{possible target of asm goto statement}} +} _______________________________________________ cfe-commits mailing list [email protected] https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
