| Message ID | 20150929214350.44b076c7@pinnacle.lan |
|---|---|
| State | New, archived |
| Headers |
Received: (qmail 129350 invoked by alias); 30 Sep 2015 04:43:55 -0000 Mailing-List: contact gdb-patches-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: <gdb-patches.sourceware.org> List-Unsubscribe: <mailto:gdb-patches-unsubscribe-##L=##H@sourceware.org> List-Subscribe: <mailto:gdb-patches-subscribe@sourceware.org> List-Archive: <http://sourceware.org/ml/gdb-patches/> List-Post: <mailto:gdb-patches@sourceware.org> List-Help: <mailto:gdb-patches-help@sourceware.org>, <http://sourceware.org/ml/#faqs> Sender: gdb-patches-owner@sourceware.org Delivered-To: mailing list gdb-patches@sourceware.org Received: (qmail 129159 invoked by uid 89); 30 Sep 2015 04:43:54 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-3.7 required=5.0 tests=AWL, BAYES_00, SPF_HELO_PASS, T_RP_MATCHES_RCVD autolearn=ham version=3.3.2 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 (AES256-GCM-SHA384 encrypted) ESMTPS; Wed, 30 Sep 2015 04:43:53 +0000 Received: from int-mx14.intmail.prod.int.phx2.redhat.com (int-mx14.intmail.prod.int.phx2.redhat.com [10.5.11.27]) by mx1.redhat.com (Postfix) with ESMTPS id BD08A8E715 for <gdb-patches@sourceware.org>; Wed, 30 Sep 2015 04:43:52 +0000 (UTC) Received: from pinnacle.lan ([10.3.113.5]) by int-mx14.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id t8U4hpJF022389 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA256 bits=256 verify=NO) for <gdb-patches@sourceware.org>; Wed, 30 Sep 2015 00:43:52 -0400 Date: Tue, 29 Sep 2015 21:43:50 -0700 From: Kevin Buettner <kevinb@redhat.com> To: gdb-patches@sourceware.org Subject: [PATCH] infcmd.c: Don't attempt to record a NULL value after a finish command Message-ID: <20150929214350.44b076c7@pinnacle.lan> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-IsSubscribed: yes |
Commit Message
Kevin Buettner
Sept. 30, 2015, 4:43 a.m. UTC
Architectures which use RETURN_VALUE_STRUCT_CONVENTION will have a
NULL return value after executing a finish command. See get_return_value()
in infcmd.c.
This patch avoids an eventual SIGSEV (caused by attempting to
derefrence a NULL pointer) by adding a suitable test to
finish_command_fsm_should_stop().
I encountered this problem while testing msp430:
(gdb) PASS: gdb.base/structs.exp: zed L<n> for finish; return 1 structs-tc
finish
Run till exit from #0 fun1 () at /ironwood1/sourceware-git/msp430-elf/../binutils-gdb/gdb/testsuite/gdb.base/structs.c:125
ERROR: Process no longer exists
gdb/ChangeLog:
* infcmd.c (finish_command_fsm_should_stop): Don't attempt to
record a NULL value.
---
gdb/infcmd.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
Comments
On 09/30/2015 05:43 AM, Kevin Buettner wrote: > Architectures which use RETURN_VALUE_STRUCT_CONVENTION will have a > NULL return value after executing a finish command. See get_return_value() > in infcmd.c. > > This patch avoids an eventual SIGSEV (caused by attempting to > derefrence a NULL pointer) by adding a suitable test to > finish_command_fsm_should_stop(). > > I encountered this problem while testing msp430: > > (gdb) PASS: gdb.base/structs.exp: zed L<n> for finish; return 1 structs-tc > finish > Run till exit from #0 fun1 () at /ironwood1/sourceware-git/msp430-elf/../binutils-gdb/gdb/testsuite/gdb.base/structs.c:125 > ERROR: Process no longer exists > > gdb/ChangeLog: > * infcmd.c (finish_command_fsm_should_stop): Don't attempt to > record a NULL value. > --- > gdb/infcmd.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/gdb/infcmd.c b/gdb/infcmd.c > index c4d7d8b..6be95e4 100644 > --- a/gdb/infcmd.c > +++ b/gdb/infcmd.c > @@ -1788,7 +1788,7 @@ finish_command_fsm_should_stop (struct thread_fsm *self) > internal_error (__FILE__, __LINE__, > _("finish_command: function has no target type")); > > - if (TYPE_CODE (rv->type) != TYPE_CODE_VOID) > + if (rv->value != NULL && TYPE_CODE (rv->type) != TYPE_CODE_VOID) > { > struct value *func; It's this else block that below sets rv->value in the first place: if (TYPE_CODE (rv->type) != TYPE_CODE_VOID) { struct value *func; func = read_var_value (f->function, NULL, get_current_frame ()); rv->value = get_return_value (func, rv->type); rv->value_history_index = record_latest_value (rv->value); } So seems like that patch would break !RETURN_VALUE_STRUCT_CONVENTION targets? I assume that it's record_latest_value that crashes? Isn't the right fix instead: rv->value = get_return_value (func, rv->type); - rv->value_history_index = record_latest_value (rv->value); + if (rv->value != NULL) + rv->value_history_index = record_latest_value (rv->value); ? Thanks, Pedro Alves
On Wed, 30 Sep 2015 11:27:25 +0100 Pedro Alves <palves@redhat.com> wrote: > On 09/30/2015 05:43 AM, Kevin Buettner wrote: > > Architectures which use RETURN_VALUE_STRUCT_CONVENTION will have a > > NULL return value after executing a finish command. See get_return_value() > > in infcmd.c. > > > > This patch avoids an eventual SIGSEV (caused by attempting to > > derefrence a NULL pointer) by adding a suitable test to > > finish_command_fsm_should_stop(). > > > > I encountered this problem while testing msp430: > > > > (gdb) PASS: gdb.base/structs.exp: zed L<n> for finish; return 1 structs-tc > > finish > > Run till exit from #0 fun1 () at /ironwood1/sourceware-git/msp430-elf/../binutils-gdb/gdb/testsuite/gdb.base/structs.c:125 > > ERROR: Process no longer exists > > > > gdb/ChangeLog: > > * infcmd.c (finish_command_fsm_should_stop): Don't attempt to > > record a NULL value. > > --- > > gdb/infcmd.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/gdb/infcmd.c b/gdb/infcmd.c > > index c4d7d8b..6be95e4 100644 > > --- a/gdb/infcmd.c > > +++ b/gdb/infcmd.c > > @@ -1788,7 +1788,7 @@ finish_command_fsm_should_stop (struct thread_fsm *self) > > internal_error (__FILE__, __LINE__, > > _("finish_command: function has no target type")); > > > > - if (TYPE_CODE (rv->type) != TYPE_CODE_VOID) > > + if (rv->value != NULL && TYPE_CODE (rv->type) != TYPE_CODE_VOID) > > { > > struct value *func; > > It's this else block that below sets rv->value in the first place: > > if (TYPE_CODE (rv->type) != TYPE_CODE_VOID) > { > struct value *func; > > func = read_var_value (f->function, NULL, get_current_frame ()); > rv->value = get_return_value (func, rv->type); > rv->value_history_index = record_latest_value (rv->value); > } > > So seems like that patch would break !RETURN_VALUE_STRUCT_CONVENTION > targets? > > I assume that it's record_latest_value that crashes? Isn't the right > fix instead: > > rv->value = get_return_value (func, rv->type); > - rv->value_history_index = record_latest_value (rv->value); > + if (rv->value != NULL) > + rv->value_history_index = record_latest_value (rv->value); > You're right. (I honestly don't know what I was thinking.) Please commit your patch instead. Thanks, Kevin
On 09/30/2015 01:17 PM, Kevin Buettner wrote: > On Wed, 30 Sep 2015 11:27:25 +0100 > Pedro Alves <palves@redhat.com> wrote: > >> On 09/30/2015 05:43 AM, Kevin Buettner wrote: >>> Architectures which use RETURN_VALUE_STRUCT_CONVENTION will have a >>> NULL return value after executing a finish command. See get_return_value() >>> in infcmd.c. >>> >>> This patch avoids an eventual SIGSEV (caused by attempting to >>> derefrence a NULL pointer) by adding a suitable test to >>> finish_command_fsm_should_stop(). >>> >>> I encountered this problem while testing msp430: >>> >>> (gdb) PASS: gdb.base/structs.exp: zed L<n> for finish; return 1 structs-tc >>> finish >>> Run till exit from #0 fun1 () at /ironwood1/sourceware-git/msp430-elf/../binutils-gdb/gdb/testsuite/gdb.base/structs.c:125 >>> ERROR: Process no longer exists >>> >>> gdb/ChangeLog: >>> * infcmd.c (finish_command_fsm_should_stop): Don't attempt to >>> record a NULL value. >>> --- >>> gdb/infcmd.c | 2 +- >>> 1 file changed, 1 insertion(+), 1 deletion(-) >>> >>> diff --git a/gdb/infcmd.c b/gdb/infcmd.c >>> index c4d7d8b..6be95e4 100644 >>> --- a/gdb/infcmd.c >>> +++ b/gdb/infcmd.c >>> @@ -1788,7 +1788,7 @@ finish_command_fsm_should_stop (struct thread_fsm *self) >>> internal_error (__FILE__, __LINE__, >>> _("finish_command: function has no target type")); >>> >>> - if (TYPE_CODE (rv->type) != TYPE_CODE_VOID) >>> + if (rv->value != NULL && TYPE_CODE (rv->type) != TYPE_CODE_VOID) >>> { >>> struct value *func; >> >> It's this else block that below sets rv->value in the first place: >> >> if (TYPE_CODE (rv->type) != TYPE_CODE_VOID) >> { >> struct value *func; >> >> func = read_var_value (f->function, NULL, get_current_frame ()); >> rv->value = get_return_value (func, rv->type); >> rv->value_history_index = record_latest_value (rv->value); >> } >> >> So seems like that patch would break !RETURN_VALUE_STRUCT_CONVENTION >> targets? >> >> I assume that it's record_latest_value that crashes? Isn't the right >> fix instead: >> >> rv->value = get_return_value (func, rv->type); >> - rv->value_history_index = record_latest_value (rv->value); >> + if (rv->value != NULL) >> + rv->value_history_index = record_latest_value (rv->value); >> > > You're right. (I honestly don't know what I was thinking.) > > Please commit your patch instead. I don't have a patch -- I wrote that hunk by hand in the mail client. :-) Please fix up yours and push it. Thanks, Pedro Alves
On Wed, 30 Sep 2015 13:21:34 +0100 Pedro Alves <palves@redhat.com> wrote: > >> I assume that it's record_latest_value that crashes? Isn't the right > >> fix instead: > >> > >> rv->value = get_return_value (func, rv->type); > >> - rv->value_history_index = record_latest_value (rv->value); > >> + if (rv->value != NULL) > >> + rv->value_history_index = record_latest_value (rv->value); > >> > > > > You're right. (I honestly don't know what I was thinking.) > > > > Please commit your patch instead. > > I don't have a patch -- I wrote that hunk by hand > in the mail client. :-) Please fix up yours and push it. Oh, okay. It's pushed. Kevin
diff --git a/gdb/infcmd.c b/gdb/infcmd.c index c4d7d8b..6be95e4 100644 --- a/gdb/infcmd.c +++ b/gdb/infcmd.c @@ -1788,7 +1788,7 @@ finish_command_fsm_should_stop (struct thread_fsm *self) internal_error (__FILE__, __LINE__, _("finish_command: function has no target type")); - if (TYPE_CODE (rv->type) != TYPE_CODE_VOID) + if (rv->value != NULL && TYPE_CODE (rv->type) != TYPE_CODE_VOID) { struct value *func;