[PATCH, committed] Fortran: NULL pointer dereference in invalid simplification [PR106985]

[Harald Anlauf <anlauf@gmx.de>]

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Dear all,

Gerhard found a NULL pointer dereference in a PARAMETER declaration
that referenced the same declared parameter.

Simple & obvious enough, see attached patch.

Regtested on x86_64-pc-linux-gnu, and pushed to mainline:

https://gcc.gnu.org/g:8dbb15bc2d019488240c1e69d93121b0347ac092

Thanks,
Harald


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From 8dbb15bc2d019488240c1e69d93121b0347ac092 Mon Sep 17 00:00:00 2001
From: Harald Anlauf <anlauf@gmx.de>
Date: Tue, 20 Sep 2022 22:23:43 +0200
Subject: [PATCH] Fortran: NULL pointer dereference in invalid simplification
 [PR106985]

gcc/fortran/ChangeLog:

	PR fortran/106985
	* expr.cc (gfc_simplify_expr): Avoid NULL pointer dereference.

gcc/testsuite/ChangeLog:

	PR fortran/106985
	* gfortran.dg/pr106985.f90: New test.
---
 gcc/fortran/expr.cc                    | 3 ++-
 gcc/testsuite/gfortran.dg/pr106985.f90 | 8 ++++++++
 2 files changed, 10 insertions(+), 1 deletion(-)
 create mode 100644 gcc/testsuite/gfortran.dg/pr106985.f90

diff --git a/gcc/fortran/expr.cc b/gcc/fortran/expr.cc
index be94c18c836..290ddf360c8 100644
--- a/gcc/fortran/expr.cc
+++ b/gcc/fortran/expr.cc
@@ -2287,7 +2287,8 @@ gfc_simplify_expr (gfc_expr *p, int type)
 	 initialization expression, or we want a subsection.  */
       if (p->symtree->n.sym->attr.flavor == FL_PARAMETER
 	  && (gfc_init_expr_flag || p->ref
-	      || p->symtree->n.sym->value->expr_type != EXPR_ARRAY))
+	      || (p->symtree->n.sym->value
+		  && p->symtree->n.sym->value->expr_type != EXPR_ARRAY)))
 	{
 	  if (!simplify_parameter_variable (p, type))
 	    return false;
diff --git a/gcc/testsuite/gfortran.dg/pr106985.f90 b/gcc/testsuite/gfortran.dg/pr106985.f90
new file mode 100644
index 00000000000..f4ed92577a3
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/pr106985.f90
@@ -0,0 +1,8 @@
+! { dg-do compile }
+! PR fortran/106985 - ICE in gfc_simplify_expr
+! Contributed by G.Steinmetz
+
+program p
+  integer, parameter :: a(2) = 1
+  integer, parameter :: b = a(2) + b ! { dg-error "before its definition is complete" }
+end
--
2.35.3