[PATCH] powerpc/32s: Fix kuap_kernel_restore()

[Michael Ellerman]

On Wed, 15 Sep 2021 16:12:24 +0200, Christophe Leroy wrote:
> At interrupt exit, kuap_kernel_restore() calls kuap_unclok() with the
> value contained in regs->kuap. However, when regs->kuap contains
> 0xffffffff it means that KUAP was not unlocked so calling
> kuap_unlock() is unrelevant and results in jeopardising the contents
> of kernel space segment registers.
> 
> So check that regs->kuap doesn't contain KUAP_NONE before calling
> kuap_unlock(). In the meantime it also means that if KUAP has not
> been correcly locked back at interrupt exit, it must be locked
> before continuing. This is done by checking the content of
> current->thread.kuap which was returned by kuap_get_and_assert_locked()
> 
> [...]

Applied to powerpc/fixes.

[1/1] powerpc/32s: Fix kuap_kernel_restore()
      https://git.kernel.org/powerpc/c/d93f9e23744b7bf11a98b2ddb091d129482ae179

cheers