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A programmer wants to allocate a buffer of 100 bytes of memory while debugging. The system memory allocating routine will allocate 108 bytes instead, adding 4 leading and 4 trailing guard bytes, and return a pointer shifted by the 4 leading guard bytes to the right, hiding them from the programmer. The programmer should then work with the ...
Canaries or canary words or stack cookies are known values that are placed between a buffer and control data on the stack to monitor buffer overflows. When the buffer overflows, the first data to be corrupted will usually be the canary, and a failed verification of the canary data will therefore alert of an overflow, which can then be handled, for example, by invalidating the corrupted data.
Visualization of a software buffer overflow. Data is written into A, but is too large to fit within A, so it overflows into B.. In programming and information security, a buffer overflow or buffer overrun is an anomaly whereby a program writes data to a buffer beyond the buffer's allocated memory, overwriting adjacent memory locations.
More critically, with only a 1-byte buffer there is a genuine risk that a received byte will be overwritten if interrupt service delays occur. To overcome these shortcomings, the 16550 series UARTs incorporated a 16-byte FIFO buffer with a programmable interrupt trigger of 1, 4, 8, or 14 bytes.
For example, the Rust programming language implements a borrow checker to ensure memory safety, [12] while C and C++ provide no memory safety guarantees. The substantial amount of software written in C and C++ has motivated the development of external static analysis tools like Coverity , which offers static memory analysis for C. [ 13 ]
A NOP-sled is the oldest and most widely known technique for exploiting stack buffer overflows. [2] It solves the problem of finding the exact address of the buffer by effectively increasing the size of the target area. To do this, much larger sections of the stack are corrupted with the no-op machine instruction.
A security model may be founded upon a formal model of access rights, a model of computation, a model of distributed computing, or no particular theoretical grounding at all. A computer security model is implemented through a computer security policy. For a more complete list of available articles on specific security models, see Category ...
In computer security, a shadow stack is a mechanism for protecting a procedure's stored return address, [1] such as from a stack buffer overflow. The shadow stack itself is a second, separate stack that "shadows" the program call stack. In the function prologue, a function stores its return address to both the call stack and the shadow stack.