linux-pci.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Christoph Hellwig <hch@infradead.org>
To: Sami Tolvanen <samitolvanen@google.com>
Cc: Kees Cook <keescook@chromium.org>,
	Nathan Chancellor <nathan@kernel.org>,
	Nick Desaulniers <ndesaulniers@google.com>,
	Masahiro Yamada <masahiroy@kernel.org>,
	Will Deacon <will@kernel.org>, Jessica Yu <jeyu@kernel.org>,
	Arnd Bergmann <arnd@arndb.de>, Tejun Heo <tj@kernel.org>,
	bpf@vger.kernel.org, linux-hardening@vger.kernel.org,
	linux-arch@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
	linux-kbuild@vger.kernel.org, linux-pci@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH 06/17] kthread: cfi: disable callback pointer check with modules
Date: Fri, 12 Mar 2021 06:13:04 +0000	[thread overview]
Message-ID: <20210312061304.GA2321497@infradead.org> (raw)
In-Reply-To: <20210312004919.669614-7-samitolvanen@google.com>

On Thu, Mar 11, 2021 at 04:49:08PM -0800, Sami Tolvanen wrote:
> With CONFIG_CFI_CLANG, a callback function passed to
> __kthread_queue_delayed_work from a module points to a jump table
> entry defined in the module instead of the one used in the core
> kernel, which breaks function address equality in this check:
> 
>   WARN_ON_ONCE(timer->function != kthread_delayed_work_timer_fn);
> 
> Disable the warning when CFI and modules are enabled.
> 
> Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
> ---
>  kernel/kthread.c | 8 +++++++-
>  1 file changed, 7 insertions(+), 1 deletion(-)
> 
> diff --git a/kernel/kthread.c b/kernel/kthread.c
> index 1578973c5740..af5fee350586 100644
> --- a/kernel/kthread.c
> +++ b/kernel/kthread.c
> @@ -963,7 +963,13 @@ static void __kthread_queue_delayed_work(struct kthread_worker *worker,
>  	struct timer_list *timer = &dwork->timer;
>  	struct kthread_work *work = &dwork->work;
>  
> -	WARN_ON_ONCE(timer->function != kthread_delayed_work_timer_fn);
> +	/*
> +	 * With CFI, timer->function can point to a jump table entry in a module,

you keep spewing this comment line that has exactly 81 characters and
thus badly messes up read it with a normal termina everywhere.

Maybe instead of fixing that in ever duplication hide the whole check in
a well documented helper (which would have to be a macro due to the
typing involved).

  parent reply	other threads:[~2021-03-12  6:13 UTC|newest]

Thread overview: 42+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-12  0:49 [PATCH 00/17] Add support for Clang CFI Sami Tolvanen
2021-03-12  0:49 ` [PATCH 01/17] add " Sami Tolvanen
2021-03-12  2:39   ` Kees Cook
2021-03-12  0:49 ` [PATCH 02/17] cfi: add __cficanonical Sami Tolvanen
2021-03-12  2:40   ` Kees Cook
2021-03-12 20:28   ` Bjorn Helgaas
2021-03-12  0:49 ` [PATCH 03/17] mm: add generic __va_function and __pa_function macros Sami Tolvanen
2021-03-12  2:40   ` Kees Cook
2021-03-12  0:49 ` [PATCH 04/17] module: cfi: ensure __cfi_check alignment Sami Tolvanen
2021-03-12  2:39   ` Kees Cook
2021-03-16 20:03     ` Sami Tolvanen
2021-03-12  0:49 ` [PATCH 05/17] workqueue: cfi: disable callback pointer check with modules Sami Tolvanen
2021-03-12  2:43   ` Kees Cook
2021-03-12  0:49 ` [PATCH 06/17] kthread: " Sami Tolvanen
2021-03-12  2:43   ` Kees Cook
2021-03-12  6:13   ` Christoph Hellwig [this message]
2021-03-17 16:05     ` Sami Tolvanen
2021-03-12  0:49 ` [PATCH 07/17] kallsyms: cfi: strip hashes from static functions Sami Tolvanen
2021-03-12  2:45   ` Kees Cook
2021-03-16 20:33     ` Sami Tolvanen
2021-03-12  0:49 ` [PATCH 08/17] bpf: disable CFI in dispatcher functions Sami Tolvanen
2021-03-12  2:45   ` Kees Cook
2021-03-12  0:49 ` [PATCH 09/17] lib/list_sort: fix function type mismatches Sami Tolvanen
2021-03-12  2:45   ` Kees Cook
2021-03-12  0:49 ` [PATCH 10/17] lkdtm: use __va_function Sami Tolvanen
2021-03-12  2:45   ` Kees Cook
2021-03-12  0:49 ` [PATCH 11/17] psci: use __pa_function for cpu_resume Sami Tolvanen
2021-03-12  2:45   ` Kees Cook
2021-03-12  0:49 ` [PATCH 12/17] arm64: implement __va_function Sami Tolvanen
2021-03-12  2:46   ` Kees Cook
2021-03-12  0:49 ` [PATCH 13/17] arm64: use __pa_function Sami Tolvanen
2021-03-12  2:46   ` Kees Cook
2021-03-12  0:49 ` [PATCH 14/17] arm64: add __nocfi to functions that jump to a physical address Sami Tolvanen
2021-03-12  2:47   ` Kees Cook
2021-03-12  0:49 ` [PATCH 15/17] arm64: add __nocfi to __apply_alternatives Sami Tolvanen
2021-03-12  2:50   ` Kees Cook
2021-03-12  0:49 ` [PATCH 16/17] KVM: arm64: Disable CFI for nVHE Sami Tolvanen
2021-03-12  2:50   ` Kees Cook
2021-03-12  0:49 ` [PATCH 17/17] arm64: allow CONFIG_CFI_CLANG to be selected Sami Tolvanen
2021-03-12  2:51   ` Kees Cook
2021-03-16 20:44     ` Sami Tolvanen
2021-03-16 23:02       ` Kees Cook

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=20210312061304.GA2321497@infradead.org \
    --to=hch@infradead.org \
    --cc=arnd@arndb.de \
    --cc=bpf@vger.kernel.org \
    --cc=jeyu@kernel.org \
    --cc=keescook@chromium.org \
    --cc=linux-arch@vger.kernel.org \
    --cc=linux-arm-kernel@lists.infradead.org \
    --cc=linux-hardening@vger.kernel.org \
    --cc=linux-kbuild@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-pci@vger.kernel.org \
    --cc=masahiroy@kernel.org \
    --cc=nathan@kernel.org \
    --cc=ndesaulniers@google.com \
    --cc=samitolvanen@google.com \
    --cc=tj@kernel.org \
    --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 a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).