Stack Protector buffer overflow detection


Linux Kernel Configuration
└─>General architecture-dependent options
└─>Stack Protector buffer overflow detection
In linux kernel since version 4.2 (release Date: 2015-08-30)  
This option turns on the "stack-protector" GCC feature. This
feature puts, at the beginning of functions, a canary value on
the stack just before the return address, and validates
the value just before actually returning. Stack based buffer
overflows (that need to overwrite this return address) now also
overwrite the canary, which gets detected and the attack is then
neutralized via a kernel panic.

Functions will have the stack-protector canary logic added if they
have an 8-byte or larger character array on the stack.

This feature requires gcc version 4.2 or above, or a distribution
gcc with the feature backported ("-fstack-protector").

On an x86 "defconfig" build, this feature adds canary checks to
about 3% of all kernel functions, which increases kernel code size
by about 0.3%.