Description:
------------
php gmp module uses:

mp_set_memory_functions(gmp_emalloc, gmp_erealloc, gmp_efree);

to switch to Zend memory management functions.

The problem is that there are other modules that use gmp. One is php-curl in 
case when curl uses gnutls for SSL connections (gnutls >= 3.1.1).

gnutls also uses gmp.

The problem happens when curl first uses gmp, gmp allocates some things (using 
generic memory management functions) and then php-gmp module changes memory 
management functions to own (Zend) one.

Then memory allocated by generic functions is going to be reallocated/freed 
using Zend functions which causes segfault.

Probably the solution would be to immediately set
mp_set_memory_functions
to Zend functions, before any other module has a chance to initialize gmp.

More:
http://lists.gnu.org/archive/html/help-gnutls/2012-11/msg00050.html
http://lists.gnu.org/archive/html/help-gnutls/2012-11/msg00049.html

Test script:
---------------
- build php with curl and gmp
- libcurl library needs to be built with gnutls >= 3.1.1
- run php cli
- press ctrl+D
=> result = segfault

Expected result:
----------------
No segfault.

Actual result:
--------------
Segfault.

Program received signal SIGSEGV, Segmentation fault.
0x00007fffea23ef20 in ?? ()
(gdb) bt
#0  0x00007fffea23ef20 in ?? ()
#1  0x00007fffeb445d3b in mp_clear_multi (address@hidden) at multi.c:38
#2  0x00007fffeb4472ca in ecc_del_point (p=0xc63ed0) at ecc_points.c:62
#3  0x00007fffeb446972 in _ecc_wmnaf_cache_entry_free (p=<optimized out>) at 
ecc_mulmod_cached.c:54
#4  ecc_wmnaf_cache_free () at ecc_mulmod_cached.c:68
#5  0x00007fffeb445685 in gnutls_crypto_deinit () at init.c:44
#6  0x00007fffeb3adb71 in gnutls_global_deinit () at gnutls_global.c:305
#7  0x00007fffee0c9a79 in Curl_gtls_cleanup () at gtls.c:182
#8  0x00007fffee0ca189 in Curl_ssl_cleanup () at sslgen.c:193
#9  0x00007fffee0bbbf5 in curl_global_cleanup () at easy.c:325
#10 0x00007fffee6f9bf8 in zm_shutdown_curl () from /usr/lib64/php/curl.so
#11 0x00007ffff7a96105 in module_destructor () from 
/usr/lib64/libphp_common-5.3.18.so
#12 0x00007ffff7a9b4ae in ?? () from /usr/lib64/libphp_common-5.3.18.so
#13 0x00007ffff7a9cd08 in zend_hash_graceful_reverse_destroy () from 
/usr/lib64/libphp_common-5.3.18.so
#14 0x00007ffff7a8f175 in zend_shutdown () from 
/usr/lib64/libphp_common-5.3.18.so
#15 0x00007ffff7a3e01b in php_module_shutdown () from 
/usr/lib64/libphp_common-5.3.18.so
#16 0x0000000000403406 in main ()
(gdb)