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LibC: Stop stdio from adding null terminators out of bounds (#685)

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When using the bounded string operations (e.g. snprintf), the null
terminator was always being written even if there was no space for
it (or indeed any valid buffer at all)

This overwriting caused segmentation faults and memory corruption
This commit is contained in:
Vincent Sanders 2019-10-24 13:12:37 +01:00 • committed by Andreas Kling
parent bddabad3d9
commit 1be4c6e9cf
1 changed files with 3 additions and 3 deletions
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6
Libraries/LibC/stdio.cpp
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@ -395,7 +395,6 @@ int sprintf(char* buffer, const char* fmt, ...)
va_list ap;
va_start(ap, fmt);
int ret = vsprintf(buffer, fmt, ap);
buffer[ret] = '\0';
va_end(ap);
return ret;
}
@ -413,7 +412,9 @@ int vsnprintf(char* buffer, size_t size, const char* fmt, va_list ap)
{
__vsnprintf_space_remaining = size;
int ret = printf_internal(sized_buffer_putch, buffer, fmt, ap);
buffer[ret] = '\0';
if (__vsnprintf_space_remaining) {
buffer[ret] = '\0';
}
return ret;
}
@ -422,7 +423,6 @@ int snprintf(char* buffer, size_t size, const char* fmt, ...)
va_list ap;
va_start(ap, fmt);
int ret = vsnprintf(buffer, size, fmt, ap);
buffer[ret] = '\0';
va_end(ap);
return ret;
}