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Fixed heap corruption, extra byte for NULL termination symbol #8

merged 1 commit into from Apr 30, 2017


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@kykc kykc commented Apr 30, 2017

As stated here in general case we need to allocate N+1 bytes for string of length N in order to copy over NULL termination byte, otherwise we'll corrupt heap memory with strcpy call.

So, in this case we need to allocate strlen(color_str) bytes, as we're omitting first symbol.

Testcase which I used to test if I'm right about this:

#include <stdio.h>
#include <string.h>
#include <stdlib.h>

int main()
	const char* test = "[255;255;255]";

	printf("string length: %i\n", (int)strlen(test));

	char* test_dest = malloc(strlen(test) + 1);

	test_dest[strlen(test)] = 0xFF;

	printf("value before strcpy: %hhx\n", test_dest[strlen(test)]);

	strcpy(test_dest, test);

	printf("value after strcpy: %hhx\n", test_dest[strlen(test)]);


	return 0;

@Gibtnix Gibtnix merged commit 330aa1b into Gibtnix:master Apr 30, 2017
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Gibtnix commented Apr 30, 2017

Thanks for the PR, I just merged it; however I'll also set the last byte explicitly to 0 (cf. main.c), otherwise I think it might be possible that it is initialized with something different than 0.

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