segmentation error while using mpz_powm in a loop

[shrims4u]

i am writing a milter which decrypts the email message. For decryption i am using GMP library... The code which gives the error is as follows: mpz_t bigbody,encbody,decbody,n,d,e; mpz_init_set_str (e, "5", 10); mpz_init_set_str (n, "81072118814004638617775947138239917744589505176471539666269773100315781097546894455560658571445286325125766632676152452856383447352821337178984474781813475276075048299705214136395672502245955793627681061360075723595075874516950614187016991430293887968216015097675955399134514678660046996064181098182893072761", 10); mpz_init_set_str (d, "32428847525601855447110378855295967097835802070588615866507909240126312439018757782224263428578114530050306653070460981142553378941128534871593789912725382636961637010791821646038659077539848411532121133465246631106852802485583932352673149866783600963924490576147444236696494852521901563664557493382382127469", 10); char *STR; STR=(char*)malloc(1000); mpz_t array[10]; //mpz_array_init (array, 10, 308); mpz_t array1[10]; //mpz_array_init (array1, 10, 100000); char substring[400]; int i=0,lower=0,upper=308; while(iconnection_num, substring ); lower=upper; upper=upper+308; mpz_init_set_str(array[i],substring,10); mpz_get_str (STR, 10, array[i]); strcat(STR,"\0"); syslog( LOG_INFO, "conn# %d - Encrypted-Biginteger = %s", cd->connection_num, STR ); mpz_init(array1[i]); mpz_powm (array1[i], array[i], d, n); mpz_get_str (STR, 10, array1[i]); syslog( LOG_INFO, "conn# %d - Decrypted-Biginteger = %s", cd->connection_num, STR ); size_t length; void *ret; char *decrypted; decrypted=(char*)malloc(1000); ret=mpz_export (decrypted, &length, 1,sizeof(data_buffer[0]), 0, 0, array1[i]); //ret=mpz_export (decrypted, &length, 1,sizeof(data_buffer[0]), 0, 0, array1[i]); strncpy(decrypted,ret,length); *(decrypted+length)='\0'; syslog( LOG_INFO, "conn# %d - size decrypted = %d Decrypted = %s", cd->connection_num,length, (char *)ret ); fflush(stdout); free(decrypted); fflush(stdin); mpz_clear(array[i]); mpz_clear(array1[i]); i++; } This code executes for 2 iterations and then give segmentation fault at mpz_powm( )

[David Crow]

shrims4u wrote:

...then give segmentation fault at mpz_powm( )

What are the values of array1[i], array[i], d, and n at that point?

"Old age is like a bank account. You withdraw later in life what you have deposited along the way." - Unknown

"Fireproof doesn't mean the fire will never come. It means when the fire comes that you will be able to withstand it." - Michael Simmons

[shrims4u]

the value of array[i] is a bignumber.... Also d and n are initialised... The error is at mpz_powm.... you want me to write the values in numbers???? Actually it differs each time according to the message

[David Crow]

My, point, although subtle, was to ensure that the values you are passing to that function are valid. Some functions/libraries place the onus of validation solely on the caller (rather than handle the bad input and fail gracefully)

"Old age is like a bank account. You withdraw later in life what you have deposited along the way." - Unknown

"Fireproof doesn't mean the fire will never come. It means when the fire comes that you will be able to withstand it." - Michael Simmons

[shrims4u]

yah the values that are passed are proper... The gdb output is as follows.... [New Thread -1208882288 (LWP 9012)] [New Thread -1208879424 (LWP 9009)] [New Thread -1219372144 (LWP 9017)] GNU MP: Cannot allocate memory (size=3368600780) Program received signal SIGABRT, Aborted. [Switching to Thread -1219372144 (LWP 9017)] 0x00110402 in __kernel_vsyscall ()

[shrims4u]

Also i get this message from gdb..... Program received signal SIGSEGV, Segmentation fault. [Switching to Thread -1218634864 (LWP 9064)] 0x06d0199c in __gmpz_powm () from /usr/lib/sse2/libgmp.so.3

[jeron1]

You certainly did not deserve to be down voted for that response.

[molesworth]

shrims4u wrote:

GNU MP: Cannot allocate memory (size=3368600780)

I would guess that this is related to the problem. It's tried to allocate 3 Gb of memory, and failed... As to why it's trying to allocate such a big chunk of memory, I couldn't say, but maybe stepping through until you get that error might help pin it down.

There are three kinds of people in the world - those who can count and those who can't...

[shrims4u]

i dint understand??? wat is down voting???

[shrims4u]

ill mail the whole program to uall Actually it is a milter which decrypts the incoming mail messages... /* sample_milter - example mail filter module ** ** Copyright © 2004 by Jef Poskanzer . ** All rights reserved. ** ** Redistribution and use in source and binary forms, with or without ** modification, are permitted provided that the following conditions ** are met: ** 1. Redistributions of source code must retain the above copyright ** notice, this list of conditions and the following disclaimer. ** 2. Redistributions in binary form must reproduce the above copyright ** notice, this list of conditions and the following disclaimer in the ** documentation and/or other materials provided with the distribution. ** ** THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND ** ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE ** IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ** ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE ** FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL ** DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS ** OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) ** HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT ** LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY ** OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF ** SUCH DAMAGE. ** ** For commentary on this license please see http://www.acme.com/license.html */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include "libmilter/mfapi.h" ////////////////////////////////////////////////////////////// #include "gmp.h" /* Forwards. */ static void usage( void ); static sfsistat sample_connect( SMFICTX* ctx, char* connhost, _SOCK_ADDR* connaddr ); static sfsistat sample_helo( SMFICTX* ctx, char* helohost ); static sfsistat sample_envfrom( SMFICTX* ctx, char** fromargs ); static sfsistat sample_envrcpt( SMFICTX* ctx, char** rcptargs ); static sfsistat sample_header( SMFICTX* ctx, char* name, char* value ); static sfsistat sample_eoh( SMFICTX* ctx ); static sfsistat sample_body( SMFICT

[jeron1]

When a response receives a 1 vote (located at the bottom right of the response).

[shrims4u]

will you please help me??? you understood my problem?

[shrims4u]

I dint understand what you want me to do...

[molesworth]

Somewhere the program is trying to allocate a very large amount of memory. This is, I think, the cause of your problem. I haven't used this library/package, but I'm basing my conclusion on the error mesage you posted (see my last reply). What I suggest is that you use a debugging tool to step through the program until it generates that error, and take a close look at exactly what is happening at that point. Or post here exactly which line is causing the problem.

There are three kinds of people in the world - those who can count and those who can't...