https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107426
--- Comment #12 from GCC Commits <cvs-commit at gcc dot gnu.org> --- The releases/gcc-12 branch has been updated by Mikael Morin <mik...@gcc.gnu.org>: https://gcc.gnu.org/g:38dd703d368c9e60159e6f19cfc8303ad639b557 commit r12-10305-g38dd703d368c9e60159e6f19cfc8303ad639b557 Author: Mikael Morin <mik...@gcc.gnu.org> Date: Thu Mar 21 17:27:54 2024 +0100 fortran: Ignore use statements on error [PR107426] This fixes an access to freed memory on the testcase from the PR. The problem comes from an invalid subroutine statement in an interface, which is ignored and causes the following statements forming the procedure body to be rejected. One of them use-associates the intrinsic ISO_C_BINDING module, which imports new symbols in a namespace that is freed at the time the statement is rejected. However, this creates dangling pointers as ISO_C_BINDING is special and its import creates a reference to the imported C_PTR symbol in the return type of the global intrinsic symbol for C_LOC (see the function create_intrinsic_function). This change saves and restores the list of use statements, so that rejected use statements are removed before they have a chance to be applied to the current namespace and create dangling pointers. PR fortran/107426 gcc/fortran/ChangeLog: * gfortran.h (gfc_save_module_list, gfc_restore_old_module_list): New declarations. * module.cc (old_module_list_tail): New global variable. (gfc_save_module_list, gfc_restore_old_module_list): New functions. (gfc_use_modules): Set module_list and old_module_list_tail. * parse.cc (next_statement): Save module_list before doing any work. (reject_statement): Restore module_list to its saved value. gcc/testsuite/ChangeLog: * gfortran.dg/pr89943_3.f90: Update error pattern. * gfortran.dg/pr89943_4.f90: Likewise. * gfortran.dg/use_31.f90: New test. (cherry picked from commit a44d7e8a52007c2d45217709ca02947c6600de87)
