* [PATCH] Fortran: fix NULL pointer dereference in gfc_check_dependency [PR108502]
@ 2023-01-23 21:23 Harald Anlauf
2023-01-23 21:45 ` Thomas Koenig
2023-01-23 21:47 ` Steve Kargl
0 siblings, 2 replies; 3+ messages in thread
From: Harald Anlauf @ 2023-01-23 21:23 UTC (permalink / raw)
To: fortran, gcc-patches
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Dear all,
the code in the PR demonstrates that dependency checking in the
frontend optimization was not recovering well from invalid code,
leading to a NULL pointer dereference. An easy and really obvious
fix.
Regtested on x86_64-pc-linux-gnu. OK for mainline?
Thanks,
Harald
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From d27e1b13ba312411ce271f5122f694ffe6c051e6 Mon Sep 17 00:00:00 2001
From: Harald Anlauf <anlauf@gmx.de>
Date: Mon, 23 Jan 2023 22:13:44 +0100
Subject: [PATCH] Fortran: fix NULL pointer dereference in gfc_check_dependency
[PR108502]
gcc/fortran/ChangeLog:
PR fortran/108502
* dependency.cc (gfc_check_dependency): Prevent NULL pointer
dereference while recursively checking expressions.
gcc/testsuite/ChangeLog:
PR fortran/108502
* gfortran.dg/pr108502.f90: New test.
---
gcc/fortran/dependency.cc | 5 +++++
gcc/testsuite/gfortran.dg/pr108502.f90 | 12 ++++++++++++
2 files changed, 17 insertions(+)
create mode 100644 gcc/testsuite/gfortran.dg/pr108502.f90
diff --git a/gcc/fortran/dependency.cc b/gcc/fortran/dependency.cc
index 43417a6ec76..9117825ee6e 100644
--- a/gcc/fortran/dependency.cc
+++ b/gcc/fortran/dependency.cc
@@ -1292,6 +1292,11 @@ gfc_check_dependency (gfc_expr *expr1, gfc_expr *expr2, bool identical)
if (expr1->expr_type != EXPR_VARIABLE)
gfc_internal_error ("gfc_check_dependency: expecting an EXPR_VARIABLE");
+ /* Prevent NULL pointer dereference while recursively analyzing invalid
+ expressions. */
+ if (expr2 == NULL)
+ return 0;
+
switch (expr2->expr_type)
{
case EXPR_OP:
diff --git a/gcc/testsuite/gfortran.dg/pr108502.f90 b/gcc/testsuite/gfortran.dg/pr108502.f90
new file mode 100644
index 00000000000..45f73849c57
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/pr108502.f90
@@ -0,0 +1,12 @@
+! { dg-do compile }
+! { dg-options "-O2 -ffrontend-optimize" }
+! PR fortran/108502 - ICE in gfc_check_dependency
+! Contributed by G.Steinmetz
+
+integer function n()
+ integer :: a(1)
+ a = [1] / 0
+end
+program p
+ integer :: b = n() ! { dg-error "must be an intrinsic function" }
+end
--
2.35.3
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] Fortran: fix NULL pointer dereference in gfc_check_dependency [PR108502]
2023-01-23 21:23 [PATCH] Fortran: fix NULL pointer dereference in gfc_check_dependency [PR108502] Harald Anlauf
@ 2023-01-23 21:45 ` Thomas Koenig
2023-01-23 21:47 ` Steve Kargl
1 sibling, 0 replies; 3+ messages in thread
From: Thomas Koenig @ 2023-01-23 21:45 UTC (permalink / raw)
To: Harald Anlauf, fortran, gcc-patches
Hi Harald,
> the code in the PR demonstrates that dependency checking in the
> frontend optimization was not recovering well from invalid code,
> leading to a NULL pointer dereference. An easy and really obvious
> fix.
>
> Regtested on x86_64-pc-linux-gnu. OK for mainline?
Yes indeed (and I would not have minded if you had indeed
committed it as obvious and simple).
Thanks for the patch!
Best regards
Thomas
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] Fortran: fix NULL pointer dereference in gfc_check_dependency [PR108502]
2023-01-23 21:23 [PATCH] Fortran: fix NULL pointer dereference in gfc_check_dependency [PR108502] Harald Anlauf
2023-01-23 21:45 ` Thomas Koenig
@ 2023-01-23 21:47 ` Steve Kargl
1 sibling, 0 replies; 3+ messages in thread
From: Steve Kargl @ 2023-01-23 21:47 UTC (permalink / raw)
To: Harald Anlauf via Fortran; +Cc: gcc-patches
On Mon, Jan 23, 2023 at 10:23:54PM +0100, Harald Anlauf via Fortran wrote:
>
> the code in the PR demonstrates that dependency checking in the
> frontend optimization was not recovering well from invalid code,
> leading to a NULL pointer dereference. An easy and really obvious
> fix.
>
> Regtested on x86_64-pc-linux-gnu. OK for mainline?
>
Yes. I agree patch looks obvious once the issue is found.
Thanks for the patch.
--
Steve
^ permalink raw reply [flat|nested] 3+ messages in thread
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2023-01-23 21:23 [PATCH] Fortran: fix NULL pointer dereference in gfc_check_dependency [PR108502] Harald Anlauf
2023-01-23 21:45 ` Thomas Koenig
2023-01-23 21:47 ` Steve Kargl
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