17.14.1. CONFIG_FORTIFY_SOURCE
Detects buffer overflows for us:
./build-linux --config 'CONFIG_FORTIFY_SOURCE=y' --linux-build-id fortify ./build-modules --clean ./build-modules ./build-buildroot ./run --eval-after 'insmod strlen_overflow.ko' --linux-build-id fortify
Possible dmesg output:
strlen_overflow: loading out-of-tree module taints kernel. detected buffer overflow in strlen ------------[ cut here ]------------
followed by a trace.
You may not get this error because this depends on strlen overflowing at least until the next page: if a random \0 appears soon enough, it won’t blow up as desired.
TODO not always reproducible. Find a more reproducible failure. I could not observe it on:
insmod memcpy_overflow.ko
Source: kernel_modules/strlen_overflow.c
Bibliography: https://www.reddit.com/r/hacking/comments/8h4qxk/what_a_buffer_overflow_in_the_linux_kernel_looks/