Heap Corruption Detected Error

here for a quick overview of the site Help Center Detailed answers to any questions you might have Meta Discuss the workings and policies of this site About Us Learn more about Stack Overflow heap corruption detected after normal block delete the company Business Learn more about hiring developers or posting ads with us Stack heap corruption detected after normal block free Overflow Questions Jobs Documentation Tags Users Badges Ask Question x Dismiss Join the Stack Overflow Community Stack Overflow is a community of c++ heap corruption detected when deleting 4.7 million programmers, just like you, helping each other. Join them; it only takes a minute: Sign up Heap Corruption Detected: after Normal block up vote 2 down vote favorite "CRT detected that the application wrote

Heap Corruption Detected After Normal Block C++

to memory end of heap buffer" error. It crashes when it arrives to free. Any help is appreciated. int messageFunction(char* message) { char* sPtr = strstr(message,"Subject:"); char* cPtr = strstr(message,"Content:"); char* messageSubject = (char*) malloc(cPtr - sPtr - strlen("Subject:")) char* messageContent = (char*) malloc(strlen(cPtr + strlen("Content:"))) strncpy(messageSubject, stPtr + strlen("Subject:"), cPtr - sPtr - strlen("Subject:")); messageSubject[cPtr - sPtr - strlen("Subject:")] = '\0'; strncpy(messageContent, cPtr + strlen("Content:"), strlen(cPtr + strlen("Content:"))); ... free(messageSubject); free(messageContent); crt detected that the application wrote to memory } void main() { char* message = "Subject:HelloWorldContent:MessageContent"; int result = messageFunction(message); } c visual-studio-2010 share|improve this question asked Oct 5 '13 at 23:01 user2653179 66215 add a comment| 2 Answers 2 active oldest votes up vote 4 down vote accepted You are allocating memory that is one byte too short. Your calculations are for the length of the data between e.g. "Subject:" and "Content:" but do not take into account the need for a null terminator in the string. Then when you manually add the null terminator you are invoking undefined behaviour by writing past the end of the array. Changing your code to the following should fix it. char* messageSubject = malloc(cPtr - sPtr - strlen("Subject:") + 1) char* messageContent = malloc(strlen(cPtr + strlen("Content:")) + 1) You also do not show the code in the "..." section, so you may have an unterminated string in there that if it is being processed by the string library routines could cause problems. share|improve this answer answered Oct 5 '13 at 23:16 tinman 4,51211529 Thank you sir, you save my day. I convert my code from char array to char pointer and as a mistake preserved the lenght of array, which has to be increased by 1. +1 for +1 (null terminator) heads-up. &ndas

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Heap Corruption Detected Crt Detected That The Application Wrote To Memory

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Crt Detected That The Application Wrote To Memory Before Start Of Heap Buffer

Jobs Documentation Tags Users Badges Ask Question x Dismiss Join the Stack Overflow Community Stack Overflow is a community of 4.7 million programmers, just like you, helping each other. http://stackoverflow.com/questions/19203604/heap-corruption-detected-after-normal-block Join them; it only takes a minute: Sign up Getting error while debugging “Debug Error .. Heap corruption detected” up vote 1 down vote favorite I am using Visual Studio 2005. While debugging code I am getting following error message and after that it is adding break, Debug Error ! Program :- Heap Corruption detected : after normal block http://stackoverflow.com/questions/5468245/getting-error-while-debugging-debug-error-heap-corruption-detected c#2368 at 0x01d21e30. CRT detected that the application wrote memory after end of heap buffer. Above error comes on the line delete values[i]; where values is a vector of (const wchar_t *). Anybody having idea where this error coming from? debugging visual-c++ exception visual-studio-2005 share|improve this question edited Mar 29 '11 at 5:44 Olli 1,0891127 asked Mar 29 '11 at 5:24 Sachin Doiphode 140519 2 how did you allocate values[i]? –Mat Mar 29 '11 at 5:26 add a comment| 1 Answer 1 active oldest votes up vote 0 down vote accepted This is for sure the result of a buffer write overflow. That means at some place you are writing more chars to a buffer than is allocated for it. You could use std::wstring instead of plain buffers which would eliminate the need for you to manage the buffers for you. Verify each write operation to the buffers. The overflow is detected on deletion as the heap manager then checks for some pattern at the beginning and the end of the buffers in debug

is a basic string class to help in the understanding of dynamic memory allocation and pointer arithmetic with char arrays. The class was given http://www.cplusplus.com/forum/general/94305/ to me in a very basic skeleton form with prototypes but no implementations, along with a test function to test my implementations. I CAN NOT use any C String functions in http://csweb.cs.wfu.edu/~torgerse/Kokua/More_SGI/007-2579-009/sgi_html/ch09.html this assignment. The part of the program which is troubling is the append function, which just appends a parameter string215 object to the end of the current string215 object. 1
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heap corruption // Add a suffix to the end of this string. Allocates and frees memory. void string215::append(const string215 &suffix) { int dataLength = str_len(data); char *output = new char[dataLength+suffix.length()+1]; char *outTemp = output; char *dataTemp = data; for(int x = 0; x < dataLength; x++) { *output = *dataTemp; output++; dataTemp++; } for(int y = 0; y < suffix.length(); y++) { *output heap corruption detected = suffix.getchar(y); output++; } *output = '\0'; data = outTemp; } Execution of this function causes a heap corruption: Debug Error! Program: [Source path] HEAP CORRUPTION DETECTED: after Normal block (#136) at 0x005C4CC0. CRT detected that the application wrote to memory after end of heap buffer. Here is the description of the append function: Add the suffix to the end of this string. Allocates a new, larger, array; copies the old contents, followed by the suffix, to the new array; then frees the old array and updates the pointer to the new one. I've stepped through my append function using the debugger and still can't seem to figure out what's wrong with it. The error changes to a Debug Assertion Failed as soon as I try and free up the memory I allocated for output. Adding: delete[] output; after I assign outTemp to data generates: Debug Assertion Failed! Program: [Source path]\dbgdel.cpp Line: 52 Expression: _BLOCK_TYPE_IS_VALID(pHead->nBlockUse) ... Abort || Retry || Ignore You can look at the entirety of my code here: (Updated append function is in this post) string215.cpp: http://pastebin.com/Xh2SvDKJ string215.h: http://pastebin.com/

detection and covers the following topics: "Typical Heap Corruption Problems" "Finding Heap Corruption Errors" "Heap Corruption Detection Tutorial" Typical Heap Corruption Problems Due to the dynamic nature of allocating and deallocating memory, the heap is vulnerable to the following typical corruption problems: boundary overrun: a program writes beyond the malloc region. boundary underrun: a program writes in front of the malloc region. access to uninitialized memory: a program attempts to read memory that has not yet been initialized. access to freed memory: a program attempts to read or write to memory that has been freed. double frees: a program frees some structure that it had already freed. In such a case, a subsequent reference can pick up a meaningless pointer, causing a segmentation violation. erroneous frees: a program calls free() on addresses that were not returned by malloc, such as static, global, or automatic variables, or other invalid expressions. See the malloc(3f) man page for more information. Finding Heap Corruption Errors To find heap corruption problems, you must relink your executable with the -lmalloc_ss library instead of the standard -lmalloc library. By default, the -lmalloc_ss library catches the following errors: malloc call failing (returning NULL) realloc call failing (returning NULL) realloc call with an address outside the range of heap addresses returned by malloc or memalign memalign call with an improper alignment free call with an address that is improperly aligned free call with an address outside the range of heap addresses returned by malloc or memalign If you also set the MALLOC_FASTCHK environment variable, you can catch these errors: free or realloc calls where the words prior to the user block have been corrupted free or realloc calls where the words following the user block have been corrupted free or realloc calls where the address is that of a block that has already been freed. This error may not always be detected if the area around the block is reallocated after it was first freed. Compiling with the Malloc Library You can compile your executable from scratch as follows: % cc -g -o targetprogram targetprogram.c -lmalloc_ssYou can also relink it by using: % ld -o targetprogram targetprogram.o -lmalloc_ss ...An alternative to rebuilding your executable is to use the _RLD_LIST environment variable to link the -lmalloc_ss library. See the rld(1) man page. Setting Environment Variables After compiling, invoke the Debugger with your executable