From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 118013 invoked by alias); 31 Oct 2018 18:44:22 -0000 Mailing-List: contact gdb-patches-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-patches-owner@sourceware.org Received: (qmail 117993 invoked by uid 89); 31 Oct 2018 18:44:21 -0000 Authentication-Results: sourceware.org; auth=none X-Spam-SWARE-Status: No, score=-26.9 required=5.0 tests=BAYES_00,GIT_PATCH_0,GIT_PATCH_1,GIT_PATCH_2,GIT_PATCH_3,KAM_SHORT,SPF_HELO_PASS autolearn=ham version=3.3.2 spammy=237A, 7628, 0287, 31F4 X-HELO: mx1.redhat.com Received: from mx1.redhat.com (HELO mx1.redhat.com) (209.132.183.28) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with ESMTP; Wed, 31 Oct 2018 18:44:20 +0000 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id D497283F3D; Wed, 31 Oct 2018 18:44:18 +0000 (UTC) Received: from localhost (unused-10-15-17-196.yyz.redhat.com [10.15.17.196]) by smtp.corp.redhat.com (Postfix) with ESMTP id A5838106223E; Wed, 31 Oct 2018 18:44:18 +0000 (UTC) From: Sergio Durigan Junior To: Tom Tromey Cc: gdb-patches@sourceware.org Subject: Re: [PATCH v2] Avoid crash when calling warning too early References: <20181031181820.24308-1-tom@tromey.com> Date: Wed, 31 Oct 2018 18:44:00 -0000 In-Reply-To: <20181031181820.24308-1-tom@tromey.com> (Tom Tromey's message of "Wed, 31 Oct 2018 12:18:20 -0600") Message-ID: <875zxi9csd.fsf@redhat.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/26.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain X-IsSubscribed: yes X-SW-Source: 2018-10/txt/msg00760.txt.bz2 On Wednesday, October 31 2018, Tom Tromey wrote: > I noticed that if you pass the name of an existing file (not a > directory) as the argument to --data-directory, gdb will crash: > > $ ./gdb -nx --data-directory ./gdb > ../../binutils-gdb/gdb/target.c:590:56: runtime error: member call on null pointer of type 'struct target_ops' > > This was later reported as PR gdb/23838. Thanks for the patch, Tom. > This happens because warning ends up calling > target_supports_terminal_ours, which calls current_top_target, which > returns nullptr this early. > > This fixes the problem by handling this case specially in > target_supports_terminal_ours. I also changed > target_supports_terminal_ours to return bool. This seems OK to me, and was also what part of what I was planning to do to fix: https://sourceware.org/bugzilla/show_bug.cgi?id=23555 Could you please also mention this bug on the ChangeLog? Your patch doesn't fully fix the issue, but it avoids the segfault at least. Thanks, > gdb/ChangeLog > 2018-10-31 Tom Tromey > > PR gdb/23838: > * target.h (target_supports_terminal_ours): Return bool. > * target.c (target_supports_terminal_ours): Handle case where > current_top_target returns nullptr. Return bool. > > gdb/testsuite/ChangeLog > 2018-10-31 Tom Tromey > > PR gdb/23838: > * gdb.base/warning.exp: New file. > --- > gdb/ChangeLog | 7 ++++++ > gdb/target.c | 10 +++++++-- > gdb/target.h | 2 +- > gdb/testsuite/ChangeLog | 5 +++++ > gdb/testsuite/gdb.base/warning.exp | 36 ++++++++++++++++++++++++++++++ > 5 files changed, 57 insertions(+), 3 deletions(-) > create mode 100644 gdb/testsuite/gdb.base/warning.exp > > diff --git a/gdb/target.c b/gdb/target.c > index 2d98954b54..9404025104 100644 > --- a/gdb/target.c > +++ b/gdb/target.c > @@ -584,10 +584,16 @@ target_terminal::info (const char *arg, int from_tty) > > /* See target.h. */ > > -int > +bool > target_supports_terminal_ours (void) > { > - return current_top_target ()->supports_terminal_ours (); > + /* This can be called before there is any target, so we must check > + for nullptr here. */ > + target_ops *top = current_top_target (); > + > + if (top == nullptr) > + return false; > + return top->supports_terminal_ours (); > } > > static void > diff --git a/gdb/target.h b/gdb/target.h > index a3000c80c6..6f4b73bf00 100644 > --- a/gdb/target.h > +++ b/gdb/target.h > @@ -1577,7 +1577,7 @@ extern int target_remove_breakpoint (struct gdbarch *gdbarch, > /* Return true if the target stack has a non-default > "terminal_ours" method. */ > > -extern int target_supports_terminal_ours (void); > +extern bool target_supports_terminal_ours (void); > > /* Kill the inferior process. Make it go away. */ > > diff --git a/gdb/testsuite/gdb.base/warning.exp b/gdb/testsuite/gdb.base/warning.exp > new file mode 100644 > index 0000000000..53067f48d5 > --- /dev/null > +++ b/gdb/testsuite/gdb.base/warning.exp > @@ -0,0 +1,36 @@ > +# Copyright 2018 Free Software Foundation, Inc. > + > +# This program is free software; you can redistribute it and/or modify > +# it under the terms of the GNU General Public License as published by > +# the Free Software Foundation; either version 3 of the License, or > +# (at your option) any later version. > +# > +# This program is distributed in the hope that it will be useful, > +# but WITHOUT ANY WARRANTY; without even the implied warranty of > +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the > +# GNU General Public License for more details. > +# > +# You should have received a copy of the GNU General Public License > +# along with this program. If not, see . > + > +# Test that an early warning does not cause a crash. > + > +if {[is_remote host]} { > + unsupported "warning.exp can only run on local host" > + return > +} > + > +set tname [standard_temp_file warning] > +set fd [open $tname w] > +puts $fd "anything" > +close $fd > + > +set save $INTERNAL_GDBFLAGS > +set INTERNAL_GDBFLAGS "-nw -nx -data-directory $tname" > + > +gdb_start > + > +# Make sure gdb started up. > +gdb_test "echo 23\\n" "23" > + > +set INTERNAL_GDBFLAGS $save > -- > 2.17.1 -- Sergio GPG key ID: 237A 54B1 0287 28BF 00EF 31F4 D0EB 7628 65FC 5E36 Please send encrypted e-mail if possible http://sergiodj.net/