[PATCH] Fortran: error recovery for invalid CLASS component [PR108434]

[Harald Anlauf <anlauf@gmx.de>]

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Dear all,

I intend to commit the attached obvious fix for a NULL pointer dereference
within the next 24h unless there are comment or objections.
The patch has been checked with valgrind that it prevents invalid reads
for the testcase, and it is certainly safe.

Regtested on x86_64-pc-linux-gnu.

Thanks,
Harald


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From e240637f6c2e2605a8424538bee885d899507506 Mon Sep 17 00:00:00 2001
From: Harald Anlauf <anlauf@gmx.de>
Date: Wed, 18 Jan 2023 22:13:29 +0100
Subject: [PATCH] Fortran: error recovery for invalid CLASS component
 [PR108434]

gcc/fortran/ChangeLog:

	PR fortran/108434
	* expr.cc (class_allocatable): Prevent NULL pointer dereference
	or invalid read.
	(class_pointer): Likewise.

gcc/testsuite/ChangeLog:

	PR fortran/108434
	* gfortran.dg/pr108434.f90: New test.
---
 gcc/fortran/expr.cc                    |  4 ++--
 gcc/testsuite/gfortran.dg/pr108434.f90 | 11 +++++++++++
 2 files changed, 13 insertions(+), 2 deletions(-)
 create mode 100644 gcc/testsuite/gfortran.dg/pr108434.f90

diff --git a/gcc/fortran/expr.cc b/gcc/fortran/expr.cc
index 5ec369c9cd8..3036b1be60f 100644
--- a/gcc/fortran/expr.cc
+++ b/gcc/fortran/expr.cc
@@ -4996,14 +4996,14 @@ get_union_initializer (gfc_symbol *union_type, gfc_component **map_p)
 static bool
 class_allocatable (gfc_component *comp)
 {
-  return comp->ts.type == BT_CLASS && CLASS_DATA (comp)
+  return comp->ts.type == BT_CLASS && comp->attr.class_ok && CLASS_DATA (comp)
     && CLASS_DATA (comp)->attr.allocatable;
 }

 static bool
 class_pointer (gfc_component *comp)
 {
-  return comp->ts.type == BT_CLASS && CLASS_DATA (comp)
+  return comp->ts.type == BT_CLASS && comp->attr.class_ok && CLASS_DATA (comp)
     && CLASS_DATA (comp)->attr.pointer;
 }

diff --git a/gcc/testsuite/gfortran.dg/pr108434.f90 b/gcc/testsuite/gfortran.dg/pr108434.f90
new file mode 100644
index 00000000000..e1768a57574
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/pr108434.f90
@@ -0,0 +1,11 @@
+! { dg-do compile }
+! PR fortran/108434 - ICE in class_allocatable
+! Contributed by G.Steinmetz
+
+program p
+  type t
+     class(c), pointer :: a(2) ! { dg-error "must have a deferred shape" }
+  end type t
+  class(t), allocatable :: x
+  class(t), pointer     :: y
+end
--
2.35.3