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Dirty COW (Dirty copy-on-write) is a computer security vulnerability of the Linux kernel that affected all Linux-based operating systems, including Android devices, that used older versions of the Linux kernel created before 2018.
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.
Copy-on-write (COW), also called implicit sharing [1] or shadowing, [2] is a resource-management technique [3] used in programming to manage shared data efficiently. Instead of copying data right away when multiple programs use it, the same data is shared between programs until one tries to modify it.
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.
Most buffer overflows overwrite memory from lower to higher memory addresses, so in order to overwrite the return pointer (and thus take control of the process) the canary value must also be overwritten. This value is checked to make sure it has not changed before a routine uses the return pointer on the stack. [2]
In computing, ".bak" is a filename extension commonly used to signify a backup copy of a file. When a program is about to overwrite an existing file (for example, when the user saves the document they are working on), the program may first make a copy of the existing file, with .bak appended to the filename.
If the memory has been reallocated to another process, then attempting to dereference the dangling pointer can cause segmentation faults (UNIX, Linux) or general protection faults (Windows). If the program has sufficient privileges to allow it to overwrite the bookkeeping data used by the kernel's memory allocator, the corruption can cause ...
The processor is made aware that no code exists in that part of memory and refuses to execute anything found in there. Use canaries, which are randomly placed values in a stack. At runtime, a canary is checked when a function returns. If a canary has been modified, the program stops execution and exits. This occurs on a failed Stack Overflow ...