C Programming Language :: Unpredictable segmentation fault


	Unpredictable segmentation fault I wrote this code: void * xmalloc (size_t size){ register void value = OPENSSL_malloc(size); if (value == 0) printf("virtual memory exhausted"); return value; } int _chooseTSK(char message,int seed){ _hash hash,hash2; char strp,prova,res; int result; BIGNUM mess,cmp,rem,k; BN_CTX ctx; mess=BN_new();rem=BN_new();k=BN_new();cmp=BN_new(); ctx = BN_CTX_new(); _evp_hash(&hash,message); prova=xmalloc(2strlen(hash.digest)+1); strcpy(prova,hex2str(hash.digest,hash.digest_size)); BN_hex2bn(&mess,(const char) prova); BN_set_word(k,K); BN_mod(rem,mess,k,ctx); strp=xmalloc(BN_num_bytes(mess)); strp = BN_bn2dec(mess); res = BN_bn2dec(rem); result=atoi((const char ) res); _evp_hash(&hash2,message); BN_dec2bn(&cmp,(const char) hash2.digest); OPENSSL_free(strp); OPENSSL_free(mess); OPENSSL_free(rem); OPENSSL_free(k); OPENSSL_free(cmp); BN_CTX_end(ctx); return result; } int main(int argc,char** argv){ int i,j; char* prova; char* speriamo="spero"; prova=xmalloc(strlen(argv[1])+1+5); for(i=0;i<10;i++){ printf("\n%d",_chooseTSK(argv[1],i)); } printf("\n"); for(j=0;j<1;j++){ for(i=0;i<1000;i++){ sprintf( prova, "%s\|%d",argv[1],i); printf("\n%d: %d",i,_chooseTSK(prova,i)); prova="\0"; } } free(prova); return 0; } During the execution of this program i always obtain unpredictable segmentation fault. After running it trough gdb debugger it tolds me this: Program received signal SIGSEGV, Segmentation fault. 0x08048b84 in main (argc=1, argv=0xbff8ac34) at parm_utility.c:48 48 prova=xmalloc(strlen(argv[1])+1+5); But i receive seg fault some time after 5 iteration sometime after 100 iteration, any suggestion? On Jun 3, 10:43 pm, Andrea <aciru@gmail.com> wrote: - Hide quoted text - > I wrote this code: > void xmalloc (size_t size){ > register void value = OPENSSL_malloc(size); > if (value == 0) > printf("virtual memory exhausted"); > return value; > } > int _chooseTSK(char message,int seed){ > _hash hash,hash2; > char strp,prova,res; > int result; > BIGNUM mess,cmp,rem,k; > BN_CTX ctx; > mess=BN_new();rem=BN_new();k=BN_new();cmp=BN_new(); > ctx = BN_CTX_new(); > _evp_hash(&hash,message); > prova=xmalloc(2strlen(hash.digest)+1); > strcpy(prova,hex2str(hash.digest,hash.digest_size)); > BN_hex2bn(&mess,(const char) prova); > BN_set_word(k,K); > BN_mod(rem,mess,k,ctx); > strp=xmalloc(BN_num_bytes(mess)); > strp = BN_bn2dec(mess); > res = BN_bn2dec(rem); > result=atoi((const char ) res); > _evp_hash(&hash2,message); > BN_dec2bn(&cmp,(const char) hash2.digest); > OPENSSL_free(strp); > OPENSSL_free(mess); > OPENSSL_free(rem); > OPENSSL_free(k); > OPENSSL_free(cmp); > BN_CTX_end(ctx); > return result; > } > int main(int argc,char** argv){ > int i,j; > char* prova; > char* speriamo="spero"; > prova=xmalloc(strlen(argv[1])+1+5); > for(i=0;i<10;i++){ > printf("\n%d",_chooseTSK(argv[1],i)); > } > printf("\n"); > for(j=0;j<1;j++){ > for(i=0;i<1000;i++){ > sprintf( prova, "%s\|%d",argv[1],i); > printf("\n%d: %d",i,_chooseTSK(prova,i)); > prova="\0"; > } > } > free(prova); > return 0; > } > During the execution of this program i always obtain unpredictable > segmentation fault. After running it trough gdb debugger it tolds me > this: > Program received signal SIGSEGV, Segmentation fault. > 0x08048b84 in main (argc=1, argv=0xbff8ac34) at parm_utility.c:48 > 48 prova=xmalloc(strlen(argv[1])+1+5); > But i receive seg fault some time after 5 iteration sometime after 100 > iteration, > any suggestion? Other part of my code is listed below: void xmalloc2 (size_t size){ register void value = OPENSSL_malloc(size); if (value == 0) printf("virtual memory exhausted"); return value; } int _evp_hash(_hash hash,char message){ const EVP_MD md; EVP_MD_CTX mdctx; unsigned char ret; unsigned int md_len,i; OpenSSL_add_all_digests(); md = EVP_get_digestbyname(HASH); if(!md) { printf("Unknown message digest %s\n",HASH); exit(1); } if(!(ret=(unsigned char) xmalloc2(EVP_MAX_MD_SIZE))) return NULL; EVP_DigestInit(&mdctx, md); EVP_DigestUpdate(&mdctx, message, strlen(message)); EVP_DigestFinal(&mdctx, hash->digest , &md_len); hash->digest_size=md_len; hash->digest_size=md_len; free(ret); return 0; } void print_hex(unsigned char bs, unsigned int n){ int i; for (i=0;i<n;i++){ printf("%02x",bs[i]); } } char hex2str(unsigned char hex,unsigned int len){ int i; char app[3]; char buf; //app=malloc(sizeof(char)); buf=xmalloc2(2len+1); strcpy(buf,""); for (i=0;i<len;i++){ sprintf(app,"%02x",hex[i]); strcat(buf,app); } //free(app); return buf; } I runned again gdb and this is the problem: glibc detected * malloc(): memory corruption (fast): 0x0804cc38 *** 9: 3 Program received signal SIGABRT, Aborted. 0xffffe410 in __kernel_vsyscall () Program received signal SIGSEGV, Segmentation fault. 0xb7e70be4 in lh_insert () from /usr/lib/i686/cmov/libcrypto.so.0.9.8 Andrea wrote: > During the execution of this program i always obtain unpredictable > segmentation fault. After running it trough gdb debugger it tolds me > this: > Program received signal SIGSEGV, Segmentation fault. > 0x08048b84 in main (argc=1, argv=0xbff8ac34) at parm_utility.c:48 > 48 prova=xmalloc(strlen(argv[1])+1+5); > But i receive seg fault some time after 5 iteration sometime after 100 > iteration, > any suggestion? If it seg faults during a malloc() or related call, then you've likely corrupted memory by overrunning an array boundary or the like. Start cutting down the code to isolate the problem. Brian In article <5cgre6F30t8f@mid.individual.net>, Default User <defaultuse@yahoo.com> wrote: >If it seg faults during a malloc() or related call, then you've likely >corrupted memory by overrunning an array boundary or the like. True. Or you have double-free()ed memory or, or free()ed non-malloc()ed memory, or something similar. >Start cutting down the code to isolate the problem. Most modern systems have tools to make solving this sort of problem much more efficient. For example, if you are using a unix-like system you may have a program called "valgrind" available, or your debugger may have a built-in memory-checking mode. Don't waste time doing by hand what a program can do for you. -- Richard -- "Consideration shall be given to the need for as many as 32 characters in some alphabets" - X3.4, 1963. - Hide quoted text - On Sun, 03 Jun 2007 20:43:23 -0000, Andrea <aciru@gmail.com> wrote: >I wrote this code: >void * xmalloc (size_t size){ > register void value = OPENSSL_malloc(size); > if (value == 0) > printf("virtual memory exhausted"); > return value; >} >int _chooseTSK(char message,int seed){ > _hash hash,hash2; > char strp,prova,res; > int result; > BIGNUM mess,cmp,rem,k; > BN_CTX ctx; > mess=BN_new();rem=BN_new();k=BN_new();cmp=BN_new(); > ctx = BN_CTX_new(); > _evp_hash(&hash,message); > prova=xmalloc(2strlen(hash.digest)+1); > strcpy(prova,hex2str(hash.digest,hash.digest_size)); > BN_hex2bn(&mess,(const char) prova); > BN_set_word(k,K); > BN_mod(rem,mess,k,ctx); > strp=xmalloc(BN_num_bytes(mess)); > strp = BN_bn2dec(mess); > res = BN_bn2dec(rem); > result=atoi((const char ) res); > _evp_hash(&hash2,message); > BN_dec2bn(&cmp,(const char) hash2.digest); > OPENSSL_free(strp); > OPENSSL_free(mess); > OPENSSL_free(rem); > OPENSSL_free(k); > OPENSSL_free(cmp); > BN_CTX_end(ctx); > return result; >} >int main(int argc,char** argv){ > int i,j; > char* prova; > char* speriamo="spero"; > prova=xmalloc(strlen(argv[1])+1+5); Is argc at least 2? Are you sure argv[1] exists and is not NULL? - Hide quoted text - > for(i=0;i<10;i++){ > printf("\n%d",_chooseTSK(argv[1],i)); > } > printf("\n"); > for(j=0;j<1;j++){ > for(i=0;i<1000;i++){ > sprintf( prova, "%s\|%d",argv[1],i); > printf("\n%d: %d",i,_chooseTSK(prova,i)); > prova="\0"; > } > } > free(prova); > return 0; >} >During the execution of this program i always obtain unpredictable >segmentation fault. After running it trough gdb debugger it tolds me >this: >Program received signal SIGSEGV, Segmentation fault. >0x08048b84 in main (argc=1, argv=0xbff8ac34) at parm_utility.c:48 >48 prova=xmalloc(strlen(argv[1])+1+5); >But i receive seg fault some time after 5 iteration sometime after 100 >iteration, >any suggestion? Iterations of what? You do not call main recursively. You call xmalloc with argv[1] as part of the argument only once in main and that call is not inside a loop. You call a dynamic allocation routine several times and make no effort to determine if it succeeded before dereferencing the returned value. Any allocation failure would result in undefined behavior at the point of dereference. Your code contains numerous non-standard functions and types and you give us no information about any of them. In spite of appearances, most of us are not clairvoyant. If hash.digest is really an array of bytes containing hex data that will be expanded 2 for 1 as your code suggests, then passing that array to strlen will often not produce the correct value for the size of the resulting string when passed to hex2str. This is the same mistake you made in your other message (HEXADECIMAL to STRING) earlier today. My response to that message explains the problem in detail. Once your strcpy overflows the allocated space, you have invoked undefined behavior. One of the common manifestations of this kind of undefined behavior is for future calls to malloc or free to result in a segfault because you have screwed up the internal data they use to keep track of allocations. Remove del for email - Hide quoted text - Andrea wrote: > I wrote this code: > void xmalloc (size_t size){ > register void value = OPENSSL_malloc(size); > if (value == 0) > printf("virtual memory exhausted"); > return value; > } ... snip ... > During the execution of this program i always obtain unpredictable > segmentation fault. After running it trough gdb debugger it tolds > me this: Possibly because you are using a non-existant function, OPENSSL_malloc. I didn't bother to read further. Also, all #includes are missing. This is not compilable. -- <http://www.cs.auckland.ac.nz/~pgut001/pubs/vista_cost.txt> <http://www.securityfocus.com/columnists/423> <http://www.aaxnet.com/editor/edit043.html> <http://kadaitcha.cx/vista/dogsbreakfast/index.html> cbfalconer at maineline dot net -- Posted via a free Usenet account from http://www.teranews.com "Andrea" <aciru@gmail.com> schrieb im Newsbeitrag news:1180903403.659383.283130@m36g2000hse.googlegroups.com... - Hide quoted text - >I wrote this code: > void xmalloc (size_t size){ > register void value = OPENSSL_malloc(size); > if (value == 0) > printf("virtual memory exhausted"); > return value; > } > int _chooseTSK(char message,int seed){ > _hash hash,hash2; > char strp,prova,res; > int result; > BIGNUM mess,cmp,rem,k; > BN_CTX ctx; > mess=BN_new();rem=BN_new();k=BN_new();cmp=BN_new(); > ctx = BN_CTX_new(); > _evp_hash(&hash,message); > prova=xmalloc(2strlen(hash.digest)+1); Sure prova isn't NULL? > strcpy(prova,hex2str(hash.digest,hash.digest_size)); > BN_hex2bn(&mess,(const char) prova); > BN_set_word(k,K); > BN_mod(rem,mess,k,ctx); > strp=xmalloc(BN_num_bytes(mess)); sure strp isn't NULL? > strp = BN_bn2dec(mess); Writing to strp twice? Loosing the first value creates a memory leak! > res = BN_bn2dec(rem); > result=atoi((const char ) res); > _evp_hash(&hash2,message); > BN_dec2bn(&cmp,(const char) hash2.digest); > OPENSSL_free(strp); freeing something that hasn't been malloc-ed? (assuming OPENSSL_free() calls free() and BN_bn2dec() did not use malloc() to obtain memory) > OPENSSL_free(mess); > OPENSSL_free(rem); > OPENSSL_free(k); > OPENSSL_free(cmp); > BN_CTX_end(ctx); > return result; > } > int main(int argc,char** argv){ > int i,j; > char* prova; > char* speriamo="spero"; > prova=xmalloc(strlen(argv[1])+1+5); Sure argv[1] isn't NULL before the call? Sure prova isn't NULL after the all? Better check - Hide quoted text - > for(i=0;i<10;i++){ > printf("\n%d",_chooseTSK(argv[1],i)); > } > printf("\n"); > for(j=0;j<1;j++){ > for(i=0;i<1000;i++){ > sprintf( prova, "%s\|%d",argv[1],i); > printf("\n%d: %d",i,_chooseTSK(prova,i)); > prova="\0"; > } > } > free(prova); > return 0; > } > During the execution of this program i always obtain unpredictable > segmentation fault. After running it trough gdb debugger it tolds me > this: > Program received signal SIGSEGV, Segmentation fault. > 0x08048b84 in main (argc=1, argv=0xbff8ac34) at parm_utility.c:48 > 48 prova=xmalloc(strlen(argv[1])+1+5); > But i receive seg fault some time after 5 iteration sometime after 100 > iteration, > any suggestion? Bye, Jojo Andrea wrote: <snip> > But i receive seg fault some time after 5 iteration sometime after 100 > iteration, any suggestion? You have posted a couple of basic questions, now you pull in the OpenSSL library, which isn't really supposed to be used by a newbie. Even if multiple ppl here have used this library before, OpenSSL is off-topic. To improve your chances of getting help, you should post a minimal* example, illustrating your C problem, if any. If your problem is OpenSSL specific, sci.crypt is a better place to ask. A good start, is to post code that actually compile..! Your code was so ill-formated (hard to read), that it completely turned me off. $man indent -- Tor <torust [at] online [dot] no> Others have already mentioned several good suggestions, I have but one thing left to point out immediately (Yes I know this is at the top) Andrea wrote: > void * xmalloc (size_t size){ > register void value = OPENSSL_malloc(size); > if (value == 0) > printf("virtual memory exhausted"); > return value; > } The printf() statement contains a string with no newline, I am not completely sure this will be printed on the screen if there is no other output before the program crashes. A better handling IMO would be something like this: if (!value) { fprintf(stderr,"virtual memory exhausted\n"); exit(EXIT_FAILURE/or some other suitable error code/); } Making the output of something that is clearly an error message better go to stderr so it is always* visible even if the output is piped somewhere. Immediately terminate the program with a defined error code in a case where it surely does not continue to work anyway.