Pike dumps core in f_crypt()

Imported from http://bugzilla.roxen.com/bugzilla/show_bug.cgi?id=6013

Reported by Marcus Wellhardh wellhard@roxen.com

Reported in [RT 17307].

A customer got multiple core dumps from a Roxen CMS 5.1.185:

>(gdb) bt
>#0  0xfffffd7fff0a4686 in ?? ()
>#1  0x0000000000591b9c in f_crypt (args=2) at /tmp/dist/5.0/pike.sol10_x86_64/pike/src/builtin_functions.c:2935
>#2  0x0000000000463c02 in eval_instruction (pc=0xc59a92 "")
>    at /tmp/dist/5.0/pike.sol10_x86_64/pike/src/interpret_functions.h:2348
>#3  0x000000000045d964 in catching_eval_instruction (pc=0x1147059 "ï¿½8\001!Oï¿½<F\001]")
>    at /tmp/dist/5.0/pike.sol10_x86_64/pike/src/interpret.c:2245
>#4  0x0000000000466dd7 in eval_instruction (pc=0x1147055 "Z\001")
>    at /tmp/dist/5.0/pike.sol10_x86_64/pike/src/interpret_functions.h:1317
>#5  0x00000000004696a0 in f_call_function (args=0) at /tmp/dist/5.0/pike.sol10_x86_64/pike/src/interpret.c:2213
>#6  0x0000000000559060 in new_thread_func (data=0xfffffd7fffdfd500)
>    at /tmp/dist/5.0/pike.sol10_x86_64/pike/src/threads.c:1125
>#7  0xfffffd7fff12bfbb in ?? ()
>#8  0x0000000000000000 in ?? ()

Hmm... Vad har variablerna ret och saltp för värden i frame #1?

(gdb) up
#1  0x0000000000591b9c in f_crypt (args=2) at /tmp/dist/5.0/pike.sol10_x86_64/pike/src/builtin_functions.c:2935
2935        i=!strcmp(ret,saltp);
(gdb) p ret
$1 = 0x0
(gdb) p saltp
$2 = 0x1783f50 "$apr1$b6a0dcb9$cr7NAImog6Wg7fksEL.mz0"
(gdb) list
2930      {
2931        pop_n_elems(args);
2932        push_text(ret);
2933      }else{
2934        int i;
2935        i=!strcmp(ret,saltp);
2936        pop_n_elems(args);
2937        push_int(i);
2938      }
2939    }