[gcc r11-9385] Fortran: prevent NULL pointer dereferences checking do-loop contained stuff

[Harald Anlauf <anlauf@gcc.gnu.org>]

https://gcc.gnu.org/g:689f8fed9b2a250e6cbeeec4fa882b8afd34eec8

commit r11-9385-g689f8fed9b2a250e6cbeeec4fa882b8afd34eec8
Author: Harald Anlauf <anlauf@gmx.de>
Date:   Tue Dec 14 21:02:04 2021 +0100

    Fortran: prevent NULL pointer dereferences checking do-loop contained stuff
    
    gcc/fortran/ChangeLog:
    
            PR fortran/103718
            PR fortran/103719
            * frontend-passes.c (doloop_contained_procedure_code): Add several
            checks to prevent NULL pointer dereferences on valid and invalid
            code called within do-loops.
    
    gcc/testsuite/ChangeLog:
    
            PR fortran/103718
            PR fortran/103719
            * gfortran.dg/do_check_18.f90: New test.
    
    (cherry picked from commit e866e1c92ecf88feeeafd5d55348451c9a181f3c)

Diff:
---
 gcc/fortran/frontend-passes.c             | 17 ++++++++++-------
 gcc/testsuite/gfortran.dg/do_check_18.f90 | 27 +++++++++++++++++++++++++++
 2 files changed, 37 insertions(+), 7 deletions(-)

diff --git a/gcc/fortran/frontend-passes.c b/gcc/fortran/frontend-passes.c
index 287b7d70876..10fa0ff3707 100644
--- a/gcc/fortran/frontend-passes.c
+++ b/gcc/fortran/frontend-passes.c
@@ -2390,7 +2390,7 @@ doloop_contained_procedure_code (gfc_code **c,
   switch (co->op)
     {
     case EXEC_ASSIGN:
-      if (co->expr1->symtree->n.sym == do_var)
+      if (co->expr1->symtree && co->expr1->symtree->n.sym == do_var)
 	gfc_error_now (errmsg, do_var->name, &co->loc, info->procedure->name,
 		       &info->where_do);
       break;
@@ -2411,14 +2411,14 @@ doloop_contained_procedure_code (gfc_code **c,
       break;
 
     case EXEC_OPEN:
-      if (co->ext.open->iostat
+      if (co->ext.open && co->ext.open->iostat
 	  && co->ext.open->iostat->symtree->n.sym == do_var)
 	gfc_error_now (errmsg, do_var->name, &co->ext.open->iostat->where,
 		       info->procedure->name, &info->where_do);
       break;
 
     case EXEC_CLOSE:
-      if (co->ext.close->iostat
+      if (co->ext.close && co->ext.close->iostat
 	  && co->ext.close->iostat->symtree->n.sym == do_var)
 	gfc_error_now (errmsg, do_var->name, &co->ext.close->iostat->where,
 		       info->procedure->name, &info->where_do);
@@ -2429,7 +2429,8 @@ doloop_contained_procedure_code (gfc_code **c,
 	{
 
 	case EXEC_INQUIRE:
-#define CHECK_INQ(a) do { if (co->ext.inquire->a &&			\
+#define CHECK_INQ(a) do { if (co->ext.inquire    &&			\
+			      co->ext.inquire->a &&			\
 			      co->ext.inquire->a->symtree->n.sym == do_var) \
 	      gfc_error_now (errmsg, do_var->name,			\
 			     &co->ext.inquire->a->where,		\
@@ -2448,21 +2449,23 @@ doloop_contained_procedure_code (gfc_code **c,
 #undef CHECK_INQ
 
 	case EXEC_READ:
-	  if (co->expr1 && co->expr1->symtree->n.sym == do_var)
+	  if (co->expr1 && co->expr1->symtree
+	      && co->expr1->symtree->n.sym == do_var)
 	    gfc_error_now (errmsg, do_var->name, &co->expr1->where,
 			   info->procedure->name, &info->where_do);
 
 	  /* Fallthrough.  */
 
 	case EXEC_WRITE:
-	  if (co->ext.dt->iostat
+	  if (co->ext.dt && co->ext.dt->iostat && co->ext.dt->iostat->symtree
 	      && co->ext.dt->iostat->symtree->n.sym == do_var)
 	    gfc_error_now (errmsg, do_var->name, &co->ext.dt->iostat->where,
 			   info->procedure->name, &info->where_do);
 	  break;
 
 	case EXEC_IOLENGTH:
-	  if (co->expr1 && co->expr1->symtree->n.sym == do_var)
+	  if (co->expr1 && co->expr1->symtree
+	      && co->expr1->symtree->n.sym == do_var)
 	    gfc_error_now (errmsg, do_var->name, &co->expr1->where,
 			   info->procedure->name, &info->where_do);
 	  break;
diff --git a/gcc/testsuite/gfortran.dg/do_check_18.f90 b/gcc/testsuite/gfortran.dg/do_check_18.f90
new file mode 100644
index 00000000000..b06112aa68f
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/do_check_18.f90
@@ -0,0 +1,27 @@
+! { dg-do compile }
+! PR103718,
+! PR103719 - ICE in doloop_contained_procedure_code
+! Contributed by G.Steinmetz
+
+subroutine s1
+  integer :: i
+  do i = 1, 2
+     call s
+  end do
+contains
+  subroutine s
+    integer :: n
+    inquire (iolength=n) 0  ! valid
+  end
+end
+
+subroutine s2
+  integer :: i
+  do i = 1, 2
+     call s
+  end do
+contains
+  subroutine s
+    shape(1) = 0    ! { dg-error "Non-variable expression" }
+  end
+end