On Thu, Jan 31, 2019 at 11:29 AM Thomas Garnier <thgar...@chromium.org> wrote: > > Add an off-by-default configuration option to use a global stack cookie > instead of the default TLS. This configuration option will only be used > with PIE binaries. > > For kernel stack cookie, the compiler uses the mcmodel=kernel to switch > between the fs segment to gs segment. A PIE binary does not use > mcmodel=kernel because it can be relocated anywhere, therefore the > compiler will default to the fs segment register. This is fixed on the > latest version of gcc.
I hate all these gcc-sucks-so-we-hack-it-and-change-nasty-semantics options. How about just preventing use of both stack protector and PIE unless the version of gcc in use is new enough. Also, does -mstack-protector-guard-reg not solve this? See https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81708. Or is there another bug? Or are you worried about gcc versions that don't have that feature yet?
