* Re: [PATCH] libasm: Fix use-after-free issue with circular single linked list cleanup
2023-02-17 14:00 [PATCH] libasm: Fix use-after-free issue with circular single linked list cleanup Mark Wielaard
@ 2023-02-21 12:22 ` Mark Wielaard
0 siblings, 0 replies; 2+ messages in thread
From: Mark Wielaard @ 2023-02-21 12:22 UTC (permalink / raw)
To: elfutils-devel
[-- Attachment #1: Type: text/plain, Size: 624 bytes --]
Hi,
On Fri, 2023-02-17 at 15:00 +0100, Mark Wielaard wrote:
> Pointed out by gcc 12 with -Wuse-after-free=3
>
> In function ‘free_section’
> asm_end.c:552:17: error: pointer ‘data’ used after ‘free’ [-Werror=use-after-free]
> 552 | while (oldp != scnp->content);
> | ~~~~~^~~~~~~~~~~~~~~~
> asm_end.c:550:9: note: call to ‘free’ here
> 550 | free (oldp);
> | ^~~~~~~~~~~
>
> Fix by freeing scnp->content last.
I pushed this and also committed the attached patch that adds -Wuse-
after-free=3 if the compiler supports it.
Cheers,
Mark
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From c9c055a6949702af57e46f4eac3355d4a4f94c5d Mon Sep 17 00:00:00 2001
From: Mark Wielaard <mark@klomp.org>
Date: Tue, 21 Feb 2023 13:12:38 +0100
Subject: [PATCH] configure: Check for and -Wuse-after-free=3 when available
gcc already includes -Wuse-after-free=2 in -Wall. -Wuse-after-free=3
also warns for indeterminate pointers in equality expressions.
Signed-off-by: Mark Wielaard <mark@klomp.org>
---
ChangeLog | 4 ++++
config/ChangeLog | 5 +++++
config/eu.am | 8 ++++++++
configure.ac | 11 ++++++++++-
4 files changed, 27 insertions(+), 1 deletion(-)
diff --git a/ChangeLog b/ChangeLog
index d99d837d..5da4f352 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+2023-02-21 Mark Wielaard <mark@klomp.org>
+
+ * configure.ac: Check for -Wuse-after-free=3
+
2023-02-15 Mark Wielaard <mark@klomp.org>
* configure.ac: Error out when demangler is enabled, but
diff --git a/config/ChangeLog b/config/ChangeLog
index c63caa0c..ce1f74f6 100644
--- a/config/ChangeLog
+++ b/config/ChangeLog
@@ -1,3 +1,8 @@
+2023-02-21 Mark Wielaard <mark@klomp.org>
+
+ * eu.am (USE_AFTER_FREE3_WARNING): Define.
+ (AM_CFLAGS): Use USE_AFTER_FREE3_WARNING.
+
2022-10-02 Mark Wielaard <mark@klomp.org>
* elfutils.spec.in: Update for 0.188.
diff --git a/config/eu.am b/config/eu.am
index c3cefe7e..e6c241f9 100644
--- a/config/eu.am
+++ b/config/eu.am
@@ -1,6 +1,7 @@
## Common automake fragments for elfutils subdirectory makefiles.
##
## Copyright (C) 2010, 2014, 2016 Red Hat, Inc.
+## Copyright (C) 2023, Mark J. Wielaard <mark@klomp.org>
##
## This file is part of elfutils.
##
@@ -87,10 +88,17 @@ else
NO_PACKED_NOT_ALIGNED_WARNING=
endif
+if HAVE_USE_AFTER_FREE3_WARNING
+USE_AFTER_FREE3_WARNING=-Wuse-after-free=3
+else
+USE_AFTER_FREE3_WARNING=
+endif
+
AM_CFLAGS = -std=gnu99 -Wall -Wshadow -Wformat=2 \
-Wold-style-definition -Wstrict-prototypes $(TRAMPOLINES_WARNING) \
$(LOGICAL_OP_WARNING) $(DUPLICATED_COND_WARNING) \
$(NULL_DEREFERENCE_WARNING) $(IMPLICIT_FALLTHROUGH_WARNING) \
+ $(USE_AFTER_FREE3_WARNING) \
$(if $($(*F)_no_Werror),,-Werror) \
$(if $($(*F)_no_Wunused),,-Wunused -Wextra) \
$(if $($(*F)_no_Wstack_usage),,$(STACK_USAGE_WARNING)) \
diff --git a/configure.ac b/configure.ac
index 4c8a4c31..142a89f6 100644
--- a/configure.ac
+++ b/configure.ac
@@ -2,7 +2,7 @@ dnl Process this file with autoconf to produce a configure script.
dnl Configure input file for elfutils. -*-autoconf-*-
dnl
dnl Copyright (C) 1996-2019 Red Hat, Inc.
-dnl Copyright (C) 2022 Mark J. Wielaard <mark@klomp.org>
+dnl Copyright (C) 2022, 2023 Mark J. Wielaard <mark@klomp.org>
dnl
dnl This file is part of elfutils.
dnl
@@ -618,6 +618,15 @@ CFLAGS="$old_CFLAGS"])
AM_CONDITIONAL(HAVE_NO_PACKED_NOT_ALIGNED_WARNING,
[test "x$ac_cv_no_packed_not_aligned" != "xno"])
+AC_CACHE_CHECK([whether the compiler accepts -Wuse-after-free=3], ac_cv_use_after_free3, [dnl
+old_CFLAGS="$CFLAGS"
+CFLAGS="$CFLAGS -Wuse-after-free=3 -Werror"
+AC_COMPILE_IFELSE([AC_LANG_SOURCE([])],
+ ac_cv_use_after_free3=yes, ac_cv_use_after_free3=no)
+CFLAGS="$old_CFLAGS"])
+AM_CONDITIONAL(HAVE_USE_AFTER_FREE3_WARNING,
+ [test "x$ac_cv_use_after_free3" != "xno"])
+
AC_CACHE_CHECK([whether the compiler accepts -fno-addrsig], ac_cv_fno_addrsig, [dnl
old_CFLAGS="$CFLAGS"
CFLAGS="$CFLAGS -fno-addrsig -Werror"
--
2.39.2
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