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References: <20231115203401.2495875-1-iii@linux.ibm.com> <20231115203401.2495875-29-iii@linux.ibm.com>
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From:   Alexander Potapenko <glider@google.com>
Date:   Thu, 16 Nov 2023 16:32:39 +0100
Message-ID: <CAG_fn=W2t61Y-ZTgmnu78mpcpPRCzB-hk9YZoD8RXXdaKHV0MQ@mail.gmail.com>
Subject: Re: [PATCH 28/32] s390/traps: Unpoison the kernel_stack_overflow()'s pt_regs
To:     Ilya Leoshkevich <iii@linux.ibm.com>
Cc:     Alexander Gordeev <agordeev@linux.ibm.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Christoph Lameter <cl@linux.com>,
        David Rientjes <rientjes@google.com>,
        Joonsoo Kim <iamjoonsoo.kim@lge.com>,
        Marco Elver <elver@google.com>,
        Masami Hiramatsu <mhiramat@kernel.org>,
        Pekka Enberg <penberg@kernel.org>,
        Steven Rostedt <rostedt@goodmis.org>,
        Vasily Gorbik <gor@linux.ibm.com>,
        Vlastimil Babka <vbabka@suse.cz>,
        Christian Borntraeger <borntraeger@linux.ibm.com>,
        Dmitry Vyukov <dvyukov@google.com>,
        Hyeonggon Yoo <42.hyeyoo@gmail.com>,
        kasan-dev@googlegroups.com, linux-kernel@vger.kernel.org,
        linux-mm@kvack.org, linux-s390@vger.kernel.org,
        linux-trace-kernel@vger.kernel.org,
        Mark Rutland <mark.rutland@arm.com>,
        Roman Gushchin <roman.gushchin@linux.dev>,
        Sven Schnelle <svens@linux.ibm.com>
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On Wed, Nov 15, 2023 at 9:35=E2=80=AFPM Ilya Leoshkevich <iii@linux.ibm.com=
> wrote:
>
> This is normally done by the generic entry code, but the
> kernel_stack_overflow() flow bypasses it.
>
> Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Reviewed-by: Alexander Potapenko <glider@google.com>

> ---
>  arch/s390/kernel/traps.c | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/arch/s390/kernel/traps.c b/arch/s390/kernel/traps.c
> index 1d2aa448d103..dd7362806dbb 100644
> --- a/arch/s390/kernel/traps.c
> +++ b/arch/s390/kernel/traps.c
> @@ -27,6 +27,7 @@
>  #include <linux/uaccess.h>
>  #include <linux/cpu.h>
>  #include <linux/entry-common.h>
> +#include <linux/kmsan.h>
>  #include <asm/asm-extable.h>
>  #include <asm/fpu/api.h>
>  #include <asm/vtime.h>
> @@ -260,6 +261,7 @@ static void monitor_event_exception(struct pt_regs *r=
egs)
>
>  void kernel_stack_overflow(struct pt_regs *regs)
>  {
> +       kmsan_unpoison_entry_regs(regs);

I suggest adding a comment here.