From: Catalin Marinas <catalin.marinas@arm.com>
To: Pingfan Liu <kernelfans@gmail.com>
Cc: linux-arm-kernel@lists.infradead.org,
Will Deacon <will@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
Vincenzo Frascino <vincenzo.frascino@arm.com>,
Andrey Konovalov <andreyknvl@gmail.com>,
Arnd Bergmann <arnd@arndb.de>
Subject: Re: [PATCH 2/2] arm64: uaccess: disable preempt during uaccess PSTATE.{PAN,TCO}
Date: Wed, 22 Dec 2021 13:02:44 +0000 [thread overview]
Message-ID: <YcMh9F+6OPEyUmCa@arm.com> (raw)
In-Reply-To: <20211221134242.98877-2-kernelfans@gmail.com>
On Tue, Dec 21, 2021 at 09:42:42PM +0800, Pingfan Liu wrote:
> For the pair of
> uaccess_enable_privileged()/uaccess_disable_privileged(), if preemption
> happens, the exposure of the access to user space by another code piece
> is unexpected.
How can this happen? We set PAN on exception entry.
> For the pair of
> __uaccess_enable_tco_async()/__uaccess_disable_tco_async(), the change
> of PSTATE.TCO is exposed unexpectedly.
As above, we disable TCO on exception entry.
> For the two cases, simply disable preemption to fix the issue.
>
> Signed-off-by: Pingfan Liu <kernelfans@gmail.com>
> Cc: Catalin Marinas <catalin.marinas@arm.com>
> Cc: Will Deacon <will@kernel.org>
> Cc: Mark Rutland <mark.rutland@arm.com>
> Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
> Cc: Andrey Konovalov <andreyknvl@gmail.com>
> Cc: Arnd Bergmann <arnd@arndb.de>
> To: linux-arm-kernel@lists.infradead.org
> ---
> arch/arm64/include/asm/uaccess.h | 15 +++++++++++----
> 1 file changed, 11 insertions(+), 4 deletions(-)
>
> diff --git a/arch/arm64/include/asm/uaccess.h b/arch/arm64/include/asm/uaccess.h
> index 406888877bbd..37d5531f210d 100644
> --- a/arch/arm64/include/asm/uaccess.h
> +++ b/arch/arm64/include/asm/uaccess.h
> @@ -193,14 +193,18 @@ static inline void __uaccess_enable_tco(void)
> */
> static inline void __uaccess_disable_tco_async(void)
> {
> - if (system_uses_mte_async_or_asymm_mode())
> - __uaccess_disable_tco();
> + if (system_uses_mte_async_or_asymm_mode()) {
> + __uaccess_disable_tco();
> + preempt_enable();
> + }
> }
>
> static inline void __uaccess_enable_tco_async(void)
> {
> - if (system_uses_mte_async_or_asymm_mode())
> + if (system_uses_mte_async_or_asymm_mode()) {
> + preempt_disable();
> __uaccess_enable_tco();
> + }
> }
As with the previous patch, disabling preemption prior to a
might_sleep() is wrong.
--
Catalin
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2021-12-22 13:04 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-12-21 13:42 [PATCH 1/2] arm64: uaccess: disable preempt during uaccess through ttbr0 Pingfan Liu
2021-12-21 13:42 ` [PATCH 2/2] arm64: uaccess: disable preempt during uaccess PSTATE.{PAN, TCO} Pingfan Liu
2021-12-22 13:02 ` Catalin Marinas [this message]
2021-12-23 9:39 ` [PATCH 2/2] arm64: uaccess: disable preempt during uaccess PSTATE.{PAN,TCO} Pingfan Liu
2021-12-22 12:59 ` [PATCH 1/2] arm64: uaccess: disable preempt during uaccess through ttbr0 Catalin Marinas
2021-12-23 9:36 ` Pingfan Liu
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=YcMh9F+6OPEyUmCa@arm.com \
--to=catalin.marinas@arm.com \
--cc=andreyknvl@gmail.com \
--cc=arnd@arndb.de \
--cc=kernelfans@gmail.com \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=mark.rutland@arm.com \
--cc=vincenzo.frascino@arm.com \
--cc=will@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.