[RFC][AArch64] Add support for system register based stack protector canary access

Wilco Dijkstra Wilco.Dijkstra@arm.com
Tue Dec 4 03:51:00 GMT 2018


Hi,

Florian wrote:
> For userland, I would like to eventually copy the OpenBSD approach for
> architectures which have some form of PC-relative addressing: we can
> have multiple random canaries in (RELRO) .rodata in sufficiently close
> to the code that needs them (assuming that we have split .rodata).  At
> least for x86-64, I expect this to be a small win.  It's also a slight
> hardening improvement if the reference canary is not stored in writable
> memory.

On AArch64 hardware pointer signing already provides a free and more robust
implementation of stack canaries, so we could change -fstack-protector to
use that when pointer signing is enabled.

Wilco



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