From: Sasha Levin <sashal@kernel.org>
To: gregkh@linuxfoundation.org
Cc: broonie@kernel.org, catalin.marinas@arm.com,
szabolcs.nagy@arm.com, stable@vger.kernel.org
Subject: Re: FAILED: patch "[PATCH] arm64: Always force a branch protection mode when the" failed to apply to 5.6-stable tree
Date: Wed, 15 Apr 2020 21:51:21 -0400 [thread overview]
Message-ID: <20200416015121.GV1068@sasha-vm> (raw)
In-Reply-To: <158694980415630@kroah.com>
On Wed, Apr 15, 2020 at 01:23:24PM +0200, gregkh@linuxfoundation.org wrote:
>
>The patch below does not apply to the 5.6-stable tree.
>If someone wants it applied there, or to any other stable or longterm
>tree, then please email the backport, including the original git commit
>id to <stable@vger.kernel.org>.
>
>thanks,
>
>greg k-h
>
>------------------ original commit in Linus's tree ------------------
>
>From b8fdef311a0bd9223f10754f94fdcf1a594a3457 Mon Sep 17 00:00:00 2001
>From: Mark Brown <broonie@kernel.org>
>Date: Tue, 31 Mar 2020 20:44:59 +0100
>Subject: [PATCH] arm64: Always force a branch protection mode when the
> compiler has one
>
>Compilers with branch protection support can be configured to enable it by
>default, it is likely that distributions will do this as part of deploying
>branch protection system wide. As well as the slight overhead from having
>some extra NOPs for unused branch protection features this can cause more
>serious problems when the kernel is providing pointer authentication to
>userspace but not built for pointer authentication itself. In that case our
>switching of keys for userspace can affect the kernel unexpectedly, causing
>pointer authentication instructions in the kernel to corrupt addresses.
>
>To ensure that we get consistent and reliable behaviour always explicitly
>initialise the branch protection mode, ensuring that the kernel is built
>the same way regardless of the compiler defaults.
>
>Fixes: 7503197562567 (arm64: add basic pointer authentication support)
>Reported-by: Szabolcs Nagy <szabolcs.nagy@arm.com>
>Signed-off-by: Mark Brown <broonie@kernel.org>
>Cc: stable@vger.kernel.org
>[catalin.marinas@arm.com: remove Kconfig option in favour of Makefile check]
>Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
I don't think that this is needed anywhere without 74afda4016a7 ("arm64:
compile the kernel with ptrauth return address signing")?
--
Thanks,
Sasha
next prev parent reply other threads:[~2020-04-16 1:51 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-15 11:23 FAILED: patch "[PATCH] arm64: Always force a branch protection mode when the" failed to apply to 5.6-stable tree gregkh
2020-04-16 1:51 ` Sasha Levin [this message]
2020-04-16 8:32 ` Catalin Marinas
2020-04-16 9:35 ` Mark Brown
2020-04-16 10:02 ` Mark Brown
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