Re: [PATCH v2 4/6] panic: Consolidate open-coded panic_on_warn checks

From: Marco Elver <elver@google.com>
To: Kees Cook <keescook@chromium.org>
Cc: Jann Horn <jannh@google.com>, Dmitry Vyukov <dvyukov@google.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Juri Lelli <juri.lelli@redhat.com>,
	Vincent Guittot <vincent.guittot@linaro.org>,
	Dietmar Eggemann <dietmar.eggemann@arm.com>,
	Steven Rostedt <rostedt@goodmis.org>,
	Ben Segall <bsegall@google.com>, Mel Gorman <mgorman@suse.de>,
	Daniel Bristot de Oliveira <bristot@redhat.com>,
	Valentin Schneider <vschneid@redhat.com>,
	Andrey Ryabinin <ryabinin.a.a@gmail.com>,
	Alexander Potapenko <glider@google.com>,
	Andrey Konovalov <andreyknvl@gmail.com>,
	Vincenzo Frascino <vincenzo.frascino@arm.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Luis Chamberlain <mcgrof@kernel.org>,
	David Gow <davidgow@google.com>,
	tangmeng <tangmeng@uniontech.com>, Petr Mladek <pmladek@suse.com>,
	"Paul E. McKenney" <paulmck@kernel.org>,
	Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
	"Guilherme G. Piccoli" <gpiccoli@igalia.com>,
	Tiezhu Yang <yangtiezhu@loongson.cn>,
	kasan-dev@googlegroups.com, linux-mm@kvack.org,
	Greg KH <gregkh@linuxfoundation.org>,
	Linus Torvalds <torvalds@linuxfoundation.org>,
	Seth Jenkins <sethjenkins@google.com>,
	Andy Lutomirski <luto@kernel.org>,
	"Eric W. Biederman" <ebiederm@xmission.com>,
	Arnd Bergmann <arnd@arndb.de>, Jonathan Corbet <corbet@lwn.net>,
	Baolin Wang <baolin.wang@linux.alibaba.com>,
	"Jason A. Donenfeld" <Jason@zx2c4.com>,
	Eric Biggers <ebiggers@google.com>,
	Huang Ying <ying.huang@intel.com>,
	Anton Vorontsov <anton@enomsg.org>,
	Mauro Carvalho Chehab <mchehab+huawei@kernel.org>,
	Laurent Dufour <ldufour@linux.ibm.com>,
	Rob Herring <robh@kernel.org>,
	linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org,
	linux-hardening@vger.kernel.org
Subject: Re: [PATCH v2 4/6] panic: Consolidate open-coded panic_on_warn checks
Date: Mon, 14 Nov 2022 10:57:15 +0100	[thread overview]
Message-ID: <CANpmjNNrYDNrRR8i+8xAFnmSjZ0Rdp-P14Sf9d+dadfsik18QA@mail.gmail.com> (raw)
In-Reply-To: <20221109200050.3400857-4-keescook@chromium.org>

On Wed, 9 Nov 2022 at 21:00, Kees Cook <keescook@chromium.org> wrote:
>
> Several run-time checkers (KASAN, UBSAN, KFENCE, KCSAN, sched) roll
> their own warnings, and each check "panic_on_warn". Consolidate this
> into a single function so that future instrumentation can be added in
> a single location.
>
> Cc: Marco Elver <elver@google.com>
> Cc: Dmitry Vyukov <dvyukov@google.com>
> Cc: Peter Zijlstra <peterz@infradead.org>
> Cc: Juri Lelli <juri.lelli@redhat.com>
> Cc: Vincent Guittot <vincent.guittot@linaro.org>
> Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
> Cc: Steven Rostedt <rostedt@goodmis.org>
> Cc: Ben Segall <bsegall@google.com>
> Cc: Mel Gorman <mgorman@suse.de>
> Cc: Daniel Bristot de Oliveira <bristot@redhat.com>
> Cc: Valentin Schneider <vschneid@redhat.com>
> Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
> Cc: Alexander Potapenko <glider@google.com>
> Cc: Andrey Konovalov <andreyknvl@gmail.com>
> Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: Luis Chamberlain <mcgrof@kernel.org>
> Cc: David Gow <davidgow@google.com>
> Cc: tangmeng <tangmeng@uniontech.com>
> Cc: Jann Horn <jannh@google.com>
> Cc: Petr Mladek <pmladek@suse.com>
> Cc: "Paul E. McKenney" <paulmck@kernel.org>
> Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
> Cc: "Guilherme G. Piccoli" <gpiccoli@igalia.com>
> Cc: Tiezhu Yang <yangtiezhu@loongson.cn>
> Cc: kasan-dev@googlegroups.com
> Cc: linux-mm@kvack.org
> Signed-off-by: Kees Cook <keescook@chromium.org>
> ---
>  include/linux/panic.h | 1 +
>  kernel/kcsan/report.c | 3 +--
>  kernel/panic.c        | 9 +++++++--
>  kernel/sched/core.c   | 3 +--
>  lib/ubsan.c           | 3 +--
>  mm/kasan/report.c     | 4 ++--
>  mm/kfence/report.c    | 3 +--
>  7 files changed, 14 insertions(+), 12 deletions(-)
>
> diff --git a/include/linux/panic.h b/include/linux/panic.h
> index c7759b3f2045..1702aeb74927 100644
> --- a/include/linux/panic.h
> +++ b/include/linux/panic.h
> @@ -11,6 +11,7 @@ extern long (*panic_blink)(int state);
>  __printf(1, 2)
>  void panic(const char *fmt, ...) __noreturn __cold;
>  void nmi_panic(struct pt_regs *regs, const char *msg);
> +void check_panic_on_warn(const char *reason);
>  extern void oops_enter(void);
>  extern void oops_exit(void);
>  extern bool oops_may_print(void);
> diff --git a/kernel/kcsan/report.c b/kernel/kcsan/report.c
> index 67794404042a..e95ce7d7a76e 100644
> --- a/kernel/kcsan/report.c
> +++ b/kernel/kcsan/report.c
> @@ -492,8 +492,7 @@ static void print_report(enum kcsan_value_change value_change,
>         dump_stack_print_info(KERN_DEFAULT);
>         pr_err("==================================================================\n");
>
> -       if (panic_on_warn)
> -               panic("panic_on_warn set ...\n");
> +       check_panic_on_warn("KCSAN");
>  }
>
>  static void release_report(unsigned long *flags, struct other_info *other_info)
> diff --git a/kernel/panic.c b/kernel/panic.c
> index 129936511380..3afd234767bc 100644
> --- a/kernel/panic.c
> +++ b/kernel/panic.c
> @@ -201,6 +201,12 @@ static void panic_print_sys_info(bool console_flush)
>                 ftrace_dump(DUMP_ALL);
>  }
>
> +void check_panic_on_warn(const char *reason)
> +{
> +       if (panic_on_warn)
> +               panic("%s: panic_on_warn set ...\n", reason);
> +}
> +
>  /**
>   *     panic - halt the system
>   *     @fmt: The text string to print
> @@ -619,8 +625,7 @@ void __warn(const char *file, int line, void *caller, unsigned taint,
>         if (regs)
>                 show_regs(regs);
>
> -       if (panic_on_warn)
> -               panic("panic_on_warn set ...\n");
> +       check_panic_on_warn("kernel");

What is the reason "kernel" in this context? The real reason is a WARN
- so would the reason "WARNING" be more intuitive?