Re: [PATCH 4.9 3/8] arm64: fix for bad_mode() handler to always result in panic

Sasha Levin
2019-11-25T13:47:03Z

On Fri, Nov 22, 2019 at 10:52:48AM +0000, Lee Jones wrote:
>From: Hari Vyas <hari.vyas@broadcom.com>
>
>[ Upstream commit e4ba15debcfd27f60d43da940a58108783bff2a6 ]
>
>The bad_mode() handler is called if we encounter an uunknown exception,
>with the expectation that the subsequent call to panic() will halt the
>system. Unfortunately, if the exception calling bad_mode() is taken from
>EL0, then the call to die() can end up killing the current user task and
>calling schedule() instead of falling through to panic().
>
>Remove the die() call altogether, since we really want to bring down the
>machine in this "impossible" case.

Should this be in newer LTS kernels too? I don't see it in 4.14. We
can't take anything into older kernels if it's not in newer ones - we
don't want to break users who update their kernels.

--
Thanks,
Sasha