For a push operation causes the value in st0 to now

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Unformatted text preview: state stored on the stack gets corrupted by a write to an outof-bounds array element. When the program then tries to reload the register or execute a ret instruction with this corrupted state, things can go seriously wrong. A particularly common source of state corruption is known as buffer overflow. Typically some character array is allocated on the stack to hold a string, but the size of the string exceeds the space allocated for the array. This is demonstrated by the following program example. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 /* Implementation of library function gets() */ char *gets(char *s) { int c; char *dest = s; while ((c = getchar()) != ’\n’ && c != EOF) *dest++ = c; *dest++ = ’\0’; /* Terminate String */ if (c == EOF) return NULL; return s; } /* Read input line and write it back */ void echo() { char buf[4]; /* Way too small! */ gets(buf); puts(buf); } The above code shows an implementation of the library function gets to demonstrate a serious problem with this functio...
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This note was uploaded on 09/02/2010 for the course ELECTRICAL 360 taught by Professor Schultz during the Spring '10 term at BYU.

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