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Memory corruption occurs in a computer program when the contents of a memory location are modified due to programmatic behavior that exceeds the intention of the original programmer or program/language constructs; this is termed as violation of memory safety.
Right before the loop starts, T[0] will be fetched from memory into cache, its value updated. However, as the loop executes, because the number of data elements the loop references requires the whole cache to be filled to its capacity, the cache block containing T[0] has to be evicted.
An accidental overflow may result in data corruption or unexpected behavior by any process that accesses the affected memory area. On operating systems without memory protection, this could be any process on the system. For example, a Microsoft JPEG GDI+ buffer overflow vulnerability could allow remote execution of code on the affected machine. [1]
A guard page typically halts the program, preventing memory corruption, but functions with large stack frames may bypass the page, and kernel code may not have the benefit of guard pages. Heap exhaustion – the program tries to allocate more memory than the amount available. In some languages, this condition must be checked for manually after ...
Another frequent source of dangling pointers is a jumbled combination of malloc() and free() library calls: a pointer becomes dangling when the block of memory it points to is freed. As with the previous example one way to avoid this is to make sure to reset the pointer to null after freeing its reference—as demonstrated below.
Data corruption can occur at any level in a system, from the host to the storage medium. Modern systems attempt to detect corruption at many layers and then recover or correct the corruption; this is almost always successful but very rarely the information arriving in the systems memory is corrupted and can cause unpredictable results.
The BIOS in some computers, when matched with operating systems such as some versions of Linux, BSD, and Windows (Windows 2000 and later [13]), allows counting of detected and corrected memory errors, in part to help identify failing memory modules before the problem becomes catastrophic.
In flash memory, a single block on the chip is designed for longer life than the others so that the memory controller can store operational data with less chance of its corruption. [ 6 ] [ 7 ] Conventional file systems such as FAT , UFS , HFS / HFS+ , EXT , and NTFS were originally designed for magnetic disks and as such rewrite many of their ...