bug#10159: 24.0.91; Segfault with auto-complete package [SEC=UNCLASSIFIED]

[Alex Murray <alex.murray@dsto.defence.gov.au>]

*UNCLASSIFIED*



On Fri 20 Jan 2012 20:31:09 CST, Eli Zaretskii wrote:
>
>>
>> Date: Fri, 20 Jan 2012 16:09:26 +1030
>> From: Alex Murray <alex.murray@dsto.defence.gov.au>
>> CC: eggert@cs.ucla.edu, 10159@debbugs.gnu.org
>>
>> One more - this time with full debugging symbols and bt full log
>> attached :)
>>
>> I'll try and keep the gdb session alive for a while if you need anything
>> further
>>
>> Program received signal SIGSEGV, Segmentation fault.
>> 0x00000000006863ea in composition_compute_stop_pos
>> (cmp_it=0x7fffffff9058, charpos=101, bytepos=118, endpos=116,
>> string=32972417) at composite.c:1073
>> 1073 elt = XCAR (val);
>> (gdb) p string
>> $1 = 32972417
>> (gdb) xtype
>> Lisp_String
>> (gdb) xstring
>> $2 = (struct Lisp_String *) 0x1f71e80
>> " Arglist: (X)", ' ' <repeats 20 times>
>
>
> Thanks. Please show the output of these GDB commands:
>
> (gdb) p val
> (gdb) xtype
> (gdb) p c
>
> The truth is you already posted information that lets me deduce the
> results, but what I see just doesn't make sense: val is shown to have
> the value of 390, which could only be an Emacs integer, and yet the
> test in the for loop:
>
> for (ridx = 0; CONSP (val); val = XCDR (val), ridx++)
>
> should have exited the loop when it sees val that is not a cons cell.
> So I don't understand how come it didn't exit, and tried to extract
> the car of something that isn't a cons cell.
>
> The value of c also looks bogus, and the values of charpos (101) and
> endpos (116) seem to be inconsistent with the length of `string',
> which is shown as " Arglist: (X)" (13 characters) plus 20 blanks, for
> a total of 33 characters.
>
> If someone who is reading this has ideas how this could happen, I'm
> all ears.
>
> Btw, Alex: what version of GCC did you use to compile Emacs?
(gdb) p val
$3 = 390
(gdb) xtype
Lisp_Cons
(gdb) p c
$4 = 14159872


gcc -v
Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-linux-gnu/4.6.1/lto-wrapper
Target: x86_64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Ubuntu/Linaro
4.6.1-9ubuntu3' --with-bugurl=file:///usr/share/doc/gcc-4.6/README.Bugs
--enable-languages=c,c++,fortran,objc,obj-c++,go --prefix=/usr
--program-suffix=-4.6 --enable-shared --enable-linker-build-id
--with-system-zlib --libexecdir=/usr/lib --without-included-gettext
--enable-threads=posix --with-gxx-include-dir=/usr/include/c++/4.6
--libdir=/usr/lib --enable-nls --with-sysroot=/ --enable-clocale=gnu
--enable-libstdcxx-debug --enable-libstdcxx-time=yes --enable-plugin
--enable-objc-gc --disable-werror --with-arch-32=i686
--with-tune=generic --enable-checking=release --build=x86_64-linux-gnu
--host=x86_64-linux-gnu --target=x86_64-linux-gnu
Thread model: posix
gcc version 4.6.1 (Ubuntu/Linaro 4.6.1-9ubuntu3)




IMPORTANT: This email remains the property of the Department of Defence and is subject to the jurisdiction of section 70 of the Crimes Act 1914. If you have received this email in error, you are requested to contact the sender and delete the email.