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POC program runs in Cygwin but not Linux (Malloc)
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copied!<p>I have a heap allocation error that I cant spot in my code that is picked up on vanguard/gdb on Linux but runs perfectly on a Windows cygwin environment. I understand that Linux could be tighter with its heap allocation than Windows but I would really like to have a response that discovers the issue/possible fix. I'm also aware that I shouldn't typecast malloc in C but it's a force of habit and doesn't change my problem from happening. My program actually compiles without error on both Linux & Windows but when I run it in Linux I get a scary looking result:</p> <blockquote> <p>malloc.c:3074: sYSMALLOc: Assertion `(old_top == (((mbinptr) (((char *) &((av)->bins[((1) - 1) * 2])) - __builtin_offsetof (struct malloc_chunk, fd)))) && old_size == 0) || ((unsigned long) (old_size) >= (unsigned long)((((__builtin_offsetof (struct malloc_chunk, fd_nextsize))+((2 * (sizeof(size_t))) - 1)) & ~((2 * (sizeof(size_t))) - 1))) && ((old_top)->size & 0x1) && ((unsigned long)old_end & pagemask) == 0)' failed. Aborted</p> </blockquote> <p>Attached snippet from my code that is being pointed to as the error for review:</p> <pre><code>/* Main */ int main(int argc, char * argv[]) { FILE *pFile; unsigned char *buffer; long int lSize; pFile = fopen ( argv[1] , "r" ); if (pFile==NULL) {fputs ("File error on arg[1]",stderr); return 1;} fseek (pFile , 0 , SEEK_END); lSize = ftell (pFile); rewind (pFile); buffer = (char*) malloc(sizeof(char) * lSize+1); if (buffer == NULL) {fputs ("Memory error",stderr); return 2;} bitpair * ppairs = (bitpair *) malloc(sizeof(bitpair) * (lSize+1)); //line 51 below calcpair(ppairs, (lSize+1)); /* irrelevant stuff */ fclose(pFile); free(buffer); free(ppairs); } typedef struct { long unsigned int a; //not actual variable names... Yes I need them to be long unsigned long unsigned int b; long unsigned int c; long unsigned int d; long unsigned int e; } bitpair; void calcpair(bitpair * ppairs, long int bits); void calcPairs(bitpair * ppairs, long int bits) { long int i, top, bot, var_1, var_2; int count = 0; for(i = 0; i < bits; i++) { top = 0; ppairs[top].e = 1; do { bot = count; count++; } while(ppairs[bot].e != 0); ppairs[bot].e = 1; var_1 = bot; var_2 = top; bitpair * bp = &ppairs[var_2]; bp->a = var_2; bp->b = var_1; bp->c = i; bp = &ppairs[var_1]; bp->a = var_2; bp->b = var_1; bp->c = i; } return; } </code></pre> <p>gdb reports: free(): invalid pointer: 0x0000000000603290 * </p> <p>valgrind reports the following message 5 times before exiting due to "VALGRIND INTERNAL ERROR" signal 11 (SIGSEGV):<br> Invalid read of size 8<br> ==2727== at 0x401043: calcPairs (in /home/user/Documents/5-3/ubuntu test/main)<br> ==2727== by 0x400C9A: main (main.c:51)<br> ==2727== Address 0x5a607a0 is not stack'd, malloc'd or (recently) free'd </p>

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