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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.
or rX,rX,rX with X=1,2,3,5,6,7 or 31 sets thread priority based on X. or r26,r26,r26 is a memory store writeback hint. xori r0,r0,0 is an explicitly unoptimized no-op for use in timing-loops. and rX,rX,rX with X=0,1 are performance-probe no-ops. ori r2,r2,0 is a "group ending NOP" in some POWER CPUs [9] PIC microcontroller: NOP: 12 bits ...
To do this, much larger sections of the stack are corrupted with the no-op machine instruction. At the end of the attacker-supplied data, after the no-op instructions, the attacker places an instruction to perform a relative jump to the top of the buffer where the shellcode is located. This collection of no-ops is referred to as the "NOP-sled ...
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.
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]
The NX bit (no-execute) is a technology used in CPUs to segregate areas of a virtual address space to store either data or processor instructions. An operating system with support for the NX bit may mark certain areas of an address space as non-executable.
In computer security and programming, a buffer over-read [1] [2] or out-of-bounds read [3] is an anomaly where a program, while reading data from a buffer, overruns the buffer's boundary and reads (or tries to read) adjacent memory.
Stack buffer overflow is a type of the more general programming malfunction known as buffer overflow (or buffer overrun). [1] Overfilling a buffer on the stack is more likely to derail program execution than overfilling a buffer on the heap because the stack contains the return addresses for all active function calls.