linux-kernel - Re: [PATCH] powerpc/mm: Fix lockup on kernel exec fault

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Date:   Tue, 06 Jul 2021 20:52:13 +1000
From:   Michael Ellerman <patch-notifications@...erman.id.au>
To:     npiggin@...il.com, Paul Mackerras <paulus@...ba.org>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Christophe Leroy <christophe.leroy@...roup.eu>,
        Michael Ellerman <mpe@...erman.id.au>
Cc:     linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org
Subject: Re: [PATCH] powerpc/mm: Fix lockup on kernel exec fault

On Thu, 1 Jul 2021 11:17:08 +0000 (UTC), Christophe Leroy wrote:
> The powerpc kernel is not prepared to handle exec faults from kernel.
> Especially, the function is_exec_fault() will return 'false' when an
> exec fault is taken by kernel, because the check is based on reading
> current->thread.regs->trap which contains the trap from user.
> 
> For instance, when provoking a LKDTM EXEC_USERSPACE test,
> current->thread.regs->trap is set to SYSCALL trap (0xc00), and
> the fault taken by the kernel is not seen as an exec fault by
> set_access_flags_filter().
> 
> [...]

Applied to powerpc/fixes.

[1/1] powerpc/mm: Fix lockup on kernel exec fault
      https://git.kernel.org/powerpc/c/cd5d5e602f502895e47e18cd46804d6d7014e65c

cheers