From 0e939c60bc55491af4fcda1fb8175ca6138c4089 Mon Sep 17 00:00:00 2001 From: Alex Coplan Date: Thu, 1 Dec 2022 17:36:02 +0000 Subject: [PATCH] varasm: Fix type confusion bug This patch fixes a type confusion bug in varasm.cc:assemble_variable. The problem is that the current code calls: sect = get_variable_section (decl, false); and then accesses sect->named.name without checking whether the section is in fact a named section. In the surrounding else clause, we only know that SECTION_STYLE (sect) != SECTION_NOSWITCH, so it is possible that the section is an unnamed section. In practice, this means that we end up doing a wild string compare between a function pointer and the string literal ".vtable_map_vars". This is because sect->named.name aliases sect->unnamed.callback in the section union. This can be seen in GDB with a simple testcase such as "int x;". This patch fixes the issue by checking the SECTION_STYLE of the section is in fact SECTION_NAMED before trying to do the string comparison. We drop the existing check of whether sect->named.name is non-NULL because this should presumably always be the case for a named section. gcc/ChangeLog: * varasm.cc (assemble_variable): Fix type confusion bug when checking for ".vtable_map_vars" section. (cherry picked from commit de144fdab17dbbb64ccb540056ab78b4ffb3fbbc) --- gcc/varasm.cc | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/gcc/varasm.cc b/gcc/varasm.cc index 021e912a37c1..a4b1cc68680d 100644 --- a/gcc/varasm.cc +++ b/gcc/varasm.cc @@ -2404,7 +2404,7 @@ assemble_variable (tree decl, int top_level ATTRIBUTE_UNUSED, else { /* Special-case handling of vtv comdat sections. */ - if (sect->named.name + if (SECTION_STYLE (sect) == SECTION_NAMED && (strcmp (sect->named.name, ".vtable_map_vars") == 0)) handle_vtv_comdat_section (sect, decl); else -- 2.47.2