[Bug c++/11648] New: gdb crashes with segmentation fault when printing larger objects

[Bug c++/11648] New: gdb crashes with segmentation fault when printing larger objects

[sven dot anderson at snom dot com]

System: Linux anderssv-lx-01 2.6.32-22-generic #33-Ubuntu SMP Wed Apr 28
13:27:30 UTC 2010 i686 GNU/Linux
Glibc: 2.11.1-0ubuntu7.1
g++: 4.4.3-4ubuntu5

The following happens only with gdb 7.1 and latest snapshot, 7.0.1 works fine.

Since my last system update to Ubuntu 10.4 I was unable to use the debugger for
our software project in eclipse. I noticed that gdb has been updated to 7.1 and
found out that I can reproduce a segmentation fault with a few steps by just
setting a breakpoint in main and from there printing a string object three times
(own implementation, not std::string) and quitting it with q each time. I will
attach a session log with glibc debugging informations and backtrace.

In eclipse it even crashes when I step through the code, but I don't know if
there are also prints involved while stepping in eclipse.

If you need any further information I will try to provide it.

-- 
           Summary: gdb crashes with segmentation fault when printing larger
                    objects
           Product: gdb
           Version: 7.1
            Status: UNCONFIRMED
          Severity: critical
          Priority: P2
         Component: c++
        AssignedTo: unassigned at sourceware dot org
        ReportedBy: sven dot anderson at snom dot com
                CC: gdb-prs at sourceware dot org,sven dot anderson at snom
                    dot com


http://sourceware.org/bugzilla/show_bug.cgi?id=11648

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[Bug c++/11648] gdb crashes with segmentation fault when printing larger objects

[sven dot anderson at snom dot com]

------- Additional Comments From sven dot anderson at snom dot com  2010-05-31 11:44 -------
Created an attachment (id=4822)
 --> (http://sourceware.org/bugzilla/attachment.cgi?id=4822&action=view)
Session log of how to produce segmantation fault


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[Bug c++/11648] gdb crashes with segmentation fault when printing larger objects

[sven dot anderson at snom dot com]

------- Additional Comments From sven dot anderson at snom dot com  2010-05-31 11:45 -------
Created an attachment (id=4823)
 --> (http://sourceware.org/bugzilla/attachment.cgi?id=4823&action=view)
Sometimes this backtrace is displayed


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[Bug c++/11648] gdb crashes with segmentation fault when printing larger objects

[sven dot anderson at snom dot com]

------- Additional Comments From sven dot anderson at snom dot com  2010-05-31 11:50 -------
I noticed that sometimes, if glibc debugging informations are installed, a
backtrace is shown (see second attachment), but this is not so easy to reproduce.

Also sometimes I manage get the following error message instead of a
segmentation fault:
value.c:627: internal-error: value_free: Assertion `val->reference_count > 0'
failed.
A problem internal to GDB has been detected, [...]


-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
     Ever Confirmed|                            |1


http://sourceware.org/bugzilla/show_bug.cgi?id=11648

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[Bug c++/11648] gdb crashes with segmentation fault when printing larger objects

[tromey at redhat dot com]

------- Additional Comments From tromey at redhat dot com  2010-06-03 15:52 -------
One thing that might be helpful is if you ran your gdb session under valgrind,
then reproduced the bug.  Be sure to have the gdb debuginfo available when
you do this.

Otherwise I think we will need a test case so we can reproduce the problem.

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[Bug c++/11648] gdb crashes with segmentation fault when printing larger objects

[steffenschmidt dot ext at siemens dot com]

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |steffenschmidt dot ext at
                   |                            |siemens dot com


http://sourceware.org/bugzilla/show_bug.cgi?id=11648

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[Bug c++/11648] gdb crashes with segmentation fault when printing larger objects

[tromey at redhat dot com]

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |WAITING


http://sourceware.org/bugzilla/show_bug.cgi?id=11648

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[Bug c++/11648] gdb crashes with segmentation fault when printing larger objects

[steffenschmidt dot ext at siemens dot com]

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|steffenschmidt dot ext at   |
                   |siemens dot com             |


http://sourceware.org/bugzilla/show_bug.cgi?id=11648

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[Bug c++/11648] gdb crashes with segmentation fault when printing larger objects

[steffen-schmidt at siemens dot com]

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |steffen-schmidt at siemens
                   |                            |dot com


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[Bug c++/11648] gdb crashes with segmentation fault when printing larger objects

[sven dot anderson at snom dot com]

------- Additional Comments From sven dot anderson at snom dot com  2010-09-21 13:56 -------
Created an attachment (id=4994)
 --> (http://sourceware.org/bugzilla/attachment.cgi?id=4994&action=view)
Backtrace of the segmentation fault when gdb is run gdb

This is a backtrace of the segmentation fault when I run the gdb inside of
another gdb session. As you can see the violation happens in obstack_free().

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[Bug c++/11648] gdb crashes with segmentation fault when printing larger objects

[sven dot anderson at snom dot com]

------- Additional Comments From sven dot anderson at snom dot com  2010-09-21 14:02 -------
Created an attachment (id=4995)
 --> (http://sourceware.org/bugzilla/attachment.cgi?id=4995&action=view)
trace of gdb running in valgrind

This is a complete trace of a gdb session running in valgrind. Search for
"Invalid free()" at the end. Again you see it happens in obstack_free().

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[Bug c++/11648] gdb crashes with segmentation fault when printing larger objects

[sven dot anderson at snom dot com]

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|WAITING                     |NEW


http://sourceware.org/bugzilla/show_bug.cgi?id=11648

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[Bug c++/11648] gdb crashes with segmentation fault when printing larger objects

[tromey at redhat dot com]

------- Additional Comments From tromey at redhat dot com  2010-09-27 17:49 -------
Could you possibly try 7.2?
This area has been reworked a bit since 7.1.

Otherwise it is hard to see how to proceed without a test case.
Unfortunately the valgrind output didn't really help me diagnose the bug.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |tromey at redhat dot com


http://sourceware.org/bugzilla/show_bug.cgi?id=11648

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[Bug c++/11648] gdb crashes with segmentation fault when printing larger objects

[sven dot anderson at snom dot com]

------- Additional Comments From sven dot anderson at snom dot com  2010-09-28 09:09 -------
Indeed, with 7.2 I cannot reproduce the crash. This is good news. But still I
will try to extract a test-case from our code.

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[Bug c++/11648] gdb crashes with segmentation fault when printing larger objects

[sven dot anderson at snom dot com]

------- Additional Comments From sven dot anderson at snom dot com  2010-09-28 12:03 -------
Created an attachment (id=5017)
 --> (http://sourceware.org/bugzilla/attachment.cgi?id=5017&action=view)
test case to crash gdb 7.1


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[Bug c++/11648] gdb crashes with segmentation fault when printing larger objects

[sven dot anderson at snom dot com]

------- Additional Comments From sven dot anderson at snom dot com  2010-09-28 12:13 -------
Created an attachment (id=5018)
 --> (http://sourceware.org/bugzilla/attachment.cgi?id=5018&action=view)
How to reproduce the crash with the test case


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[Bug c++/11648] gdb crashes with segmentation fault when printing larger objects

[sven dot anderson at snom dot com]

------- Additional Comments From sven dot anderson at snom dot com  2010-09-28 12:29 -------
Ok, in the end the test case is very simple. You just need a class with a couple
of static objects of its own. See gdb-crash.cpp.

How to reproduce:
$ g++ -g gdb-crash.cpp -o gdb-crash
$ ~/src/gdb-7.1.50.20100527/gdb/gdb gdb-crash
(gdb) b main
(gdb) r
(gdb) print global
q<return>
(gdb) print global
q<return>
(gdb) print global
-> segmentation fault
(see gdb-crash.txt for details)

My system is an up-to-date Ubuntu 10.04, 32bit, that is:

$ uname -a
Linux anderssv-lx-01 2.6.32-25-generic #44-Ubuntu SMP Fri Sep 17 20:26:08 UTC
2010 i686 GNU/Linux

and libc: 2.11.1-0ubuntu7.2 (i686 optimized version)


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[Bug c++/11648] gdb crashes with segmentation fault when printing larger objects

[sven dot anderson at snom dot com]

------- Additional Comments From sven dot anderson at snom dot com  2010-09-28 12:35 -------
Forgot the compiler:
$ g++ -v
Using built-in specs.
Target: i486-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Ubuntu 4.4.3-4ubuntu5'
--with-bugurl=file:///usr/share/doc/gcc-4.4/README.Bugs
--enable-languages=c,c++,fortran,objc,obj-c++ --prefix=/usr --enable-shared
--enable-multiarch --enable-linker-build-id --with-system-zlib
--libexecdir=/usr/lib --without-included-gettext --enable-threads=posix
--with-gxx-include-dir=/usr/include/c++/4.4 --program-suffix=-4.4 --enable-nls
--enable-clocale=gnu --enable-libstdcxx-debug --enable-plugin --enable-objc-gc
--enable-targets=all --disable-werror --with-arch-32=i486 --with-tune=generic
--enable-checking=release --build=i486-linux-gnu --host=i486-linux-gnu
--target=i486-linux-gnu
Thread model: posix
gcc version 4.4.3 (Ubuntu 4.4.3-4ubuntu5)


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