Thread: [bug fix] ECPG app crashes due to SIGBUS on SPARC Solaris

Hello,

I encountered a bug of ECPG with PG 9.2.4, which probably exists in all
releases.  The attached patch is for 9.4.  Could you review and backport
this to at least 9.2 and later?


[Problem]
The attached ECPG app crashes and dumps core with SIGBUS on Solaris for
SPARC.  I used Solaris 10, and Oracle Studio to compile the app for 64-bit
build.  The same app completes successfully on Linux and Windows for
x86/x564.

The steps to reproduce the problem is:
1. ecpg sigbus.pgc
2. cc -xtarget=generic64 -I<pgsql_dir>/include
sigbus.c -L<pgsql_dir>/lib -lecpg
3. a.out

When execting FETCH statement using an SQL descriptor, the app crashes at
the following line in ECPGdo(), which is in
src/interfaces/ecpg/ecpglib/execute.c:

    var->value = *((char **) (var->pointer));


[Cause]
ecpg outputs the following line in the preprocessed source file:

 { ECPGdo(__LINE__, 0, 1, NULL, 0, ECPGst_normal, "fetch $0",
 ECPGt_char,(cur),(long)4,(long)1,(4)*sizeof(char),
 ECPGt_NO_INDICATOR, NULL , 0L, 0L, 0L, ECPGt_EOIT,
 ECPGt_descriptor, (desc1), 0L, 0L, 0L,
 ECPGt_NO_INDICATOR, NULL , 0L, 0L, 0L, ECPGt_EORT);}

So, the above line is executed in ECPGdo().  On the other hand, desc1 is not
aligned on 8-byte boundary.  This unaligned access causes SIGBUS.


[Fix]
Because desc1 is a char array, else block should be executed instead of the
above path.

    var->value = var->pointer;

Therefore, make ecpg pass SQL descriptor host variables to ECPGdo() with
non-zero lengths.


Regards
MauMau

<div class="moz-cite-prefix">2013-12-24 13:55 keltezéssel, MauMau írta:<br /></div><blockquote
cite="mid:549B5DA0D5354DFE9787D73B07D5BFC1@maumau"type="cite">Hello, <br /><br /> I encountered a bug of ECPG with PG
9.2.4,which probably exists in all releases.  The attached patch is for 9.4.  Could you review and backport this to at
least9.2 and later? <br /><br /><br /> [Problem] <br /> The attached ECPG app</blockquote><br /> The app wasn't
attached,only the patch.<br /> If this is a small test app, it can also be a part of the patch in the form of a
regressiontest.<br /><br /><blockquote cite="mid:549B5DA0D5354DFE9787D73B07D5BFC1@maumau" type="cite"> crashes and
dumpscore with SIGBUS on Solaris for SPARC.  I used Solaris 10, and Oracle Studio to compile the app for 64-bit build. 
Thesame app completes successfully on Linux and Windows for x86/x564. <br /><br /> The steps to reproduce the problem
is:<br /> 1. ecpg sigbus.pgc <br /> 2. cc -xtarget=generic64 -I<pgsql_dir>/include sigbus.c
-L<pgsql_dir>/lib-lecpg <br /> 3. a.out <br /><br /> When execting FETCH statement using an SQL descriptor, the
appcrashes at the following line in ECPGdo(), which is in src/interfaces/ecpg/ecpglib/execute.c: <br /><br />   
var->value= *((char **) (var->pointer)); <br /><br /><br /> [Cause] <br /> ecpg outputs the following line in the
preprocessedsource file: <br /><br /> { ECPGdo(__LINE__, 0, 1, NULL, 0, ECPGst_normal, "fetch $0", <br />
ECPGt_char,(cur),(long)4,(long)1,(4)*sizeof(char),<br /> ECPGt_NO_INDICATOR, NULL , 0L, 0L, 0L, ECPGt_EOIT, <br />
ECPGt_descriptor,(desc1), 0L, 0L, 0L, <br /> ECPGt_NO_INDICATOR, NULL , 0L, 0L, 0L, ECPGt_EORT);} <br /><br /> So, the
aboveline is executed in ECPGdo().  On the other hand, desc1 is not aligned on 8-byte boundary.  This unaligned access
causesSIGBUS. <br /><br /><br /> [Fix] <br /> Because desc1 is a char array, else block should be executed instead of
theabove path. <br /><br />    var->value = var->pointer; <br /><br /> Therefore, make ecpg pass SQL descriptor
hostvariables to ECPGdo() with non-zero lengths. <br /><br /><br /> Regards <br /> MauMau <br /><br /><fieldset
class="mimeAttachmentHeader"></fieldset><br/><pre wrap="">
 
</pre></blockquote><br /><br /><pre class="moz-signature" cols="90">-- 
----------------------------------
Zoltán Böszörményi
Cybertec Schönig & Schönig GmbH
Gröhrmühlgasse 26
A-2700 Wiener Neustadt, Austria
Web: <a class="moz-txt-link-freetext" href="http://www.postgresql-support.de">http://www.postgresql-support.de</a>
<aclass="moz-txt-link-freetext" href="http://www.postgresql.at/">http://www.postgresql.at/</a>
 
</pre>

From: "Boszormenyi Zoltan" <zb@cybertec.at>
> The app wasn't attached, only the patch.
> If this is a small test app, it can also be a part of the patch in the
> form of a
> regression test.

Sorry, attached.  Thank you for pointing it out.

Regards
MauMau

On Tue, Dec 24, 2013 at 09:55:45PM +0900, MauMau wrote:
> The attached ECPG app crashes and dumps core with SIGBUS on Solaris
> for SPARC.  I used Solaris 10, and Oracle Studio to compile the app
> for 64-bit build.  The same app completes successfully on Linux and
> Windows for x86/x564.

What happens to the regression test suite on your system? There are test cases
that access a descriptor in a similar way I think.

> Because desc1 is a char array, else block should be executed instead
> of the above path.

> Therefore, make ecpg pass SQL descriptor host variables to ECPGdo()
> with non-zero lengths.

How did you decide which values to put in? I fail to see a reason for choosing
exactly these values.

Mkichael
-- 
Michael Meskes
Michael at Fam-Meskes dot De, Michael at Meskes dot (De|Com|Net|Org)
Michael at BorussiaFan dot De, Meskes at (Debian|Postgresql) dot Org
Jabber: michael.meskes at gmail dot com
VfL Borussia! Força Barça! Go SF 49ers! Use Debian GNU/Linux, PostgreSQL

From: "Michael Meskes" <meskes@postgresql.org>
> What happens to the regression test suite on your system? There are test 
> cases
> that access a descriptor in a similar way I think.

OK, I'll run the ECPG regression test on Solaris without the patch.  Please 
wait until Jan 6 2014 or so, because we've just entered new year holidays 
here in Japan.


> How did you decide which values to put in? I fail to see a reason for 
> choosing
> exactly these values.

Yes, the value is arbitrary except it should be non-zero so that ECPGdo() 
can execute the else block.  And the lengths here are irrelevant to the 
actual processing.  I thought the original 0 was chosen arbitrarily and I 
could do so too.  If I can do better, please let me know that.

Regards
MauMau

On Sat, Dec 28, 2013 at 08:04:09AM +0900, MauMau wrote:
> OK, I'll run the ECPG regression test on Solaris without the patch.
> Please wait until Jan 6 2014 or so, because we've just entered new
> year holidays here in Japan.

Sure, we're no in a particular hurry.

Michael
-- 
Michael Meskes
Michael at Fam-Meskes dot De, Michael at Meskes dot (De|Com|Net|Org)
Michael at BorussiaFan dot De, Meskes at (Debian|Postgresql) dot Org
Jabber: michael.meskes at gmail dot com
VfL Borussia! Força Barça! Go SF 49ers! Use Debian GNU/Linux, PostgreSQL

From: "Michael Meskes" <meskes@postgresql.org>
> On Sat, Dec 28, 2013 at 08:04:09AM +0900, MauMau wrote:
>> OK, I'll run the ECPG regression test on Solaris without the patch.
>> Please wait until Jan 6 2014 or so, because we've just entered new
>> year holidays here in Japan.
>
> Sure, we're no in a particular hurry.

I ran the ECPG regression test with the unpatched 64-bit PostgreSQL 9.2.4 on 
SPARC Solaris, and it succeeded (all 54 tests passed).  For information, I 
did as follows:

configure --prefix=... CC='<Oracle_Studio_HOME>/bin/cc -xtarget=generic64' 
...
gmake
gmake install
initdb -E UTF8 --no-locale
pg_ctl start
cd postgresql-9.2.4/src/interfaces/ecpg
gmake check

I guess that's that's because the regression test doesn't have a test case 
which specifies SQL descriptor name with a host variable.

Regards
MauMau

On Sun, Jan 05, 2014 at 03:42:42PM +0900, MauMau wrote:
> I ran the ECPG regression test with the unpatched 64-bit PostgreSQL
> 9.2.4 on SPARC Solaris, and it succeeded (all 54 tests passed).  For
> ...

Thanks a lot. Patch applied to HEAD and all the backbranches. Will push shortly.

Michael
-- 
Michael Meskes
Michael at Fam-Meskes dot De, Michael at Meskes dot (De|Com|Net|Org)
Michael at BorussiaFan dot De, Meskes at (Debian|Postgresql) dot Org
Jabber: michael.meskes at gmail dot com
VfL Borussia! Força Barça! Go SF 49ers! Use Debian GNU/Linux, PostgreSQL