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From: Linus Walleij <linus.walleij@linaro.org>
Date: Thu, 11 Jan 2024 00:46:19 +0100
Message-ID: <CACRpkdZCtDvrWW6AL-sX71fY1_qa858+tCR9ke6pT5HPnA7mKg@mail.gmail.com>
Subject: Re: [PATCH] ARM: unwind: Add missing "Call trace:" line
To: Kees Cook <keescook@chromium.org>
Cc: Russell King <linux@armlinux.org.uk>, Mark Brown <broonie@kernel.org>, 
	Ard Biesheuvel <ardb@kernel.org>, Arnd Bergmann <arnd@arndb.de>, 
	Vladimir Murzin <vladimir.murzin@arm.com>, Zhen Lei <thunder.leizhen@huawei.com>, 
	Keith Packard <keithpac@amazon.com>, Haibo Li <haibo.li@mediatek.com>, 
	linux-arm-kernel@lists.infradead.org, 
	Matthias Brugger <matthias.bgg@gmail.com>, 
	AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>, 
	Alexandre Mergnat <amergnat@baylibre.com>, linux-kernel@vger.kernel.org, 
	linux-hardening@vger.kernel.org
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On Wed, Jan 10, 2024 at 10:56=E2=80=AFPM Kees Cook <keescook@chromium.org> =
wrote:

> Every other architecture in Linux includes the line "Call trace:" before
> backtraces. In some cases ARM would print "Backtrace:", but this was
> only via 1 specific call path, and wasn't included in CPU Oops nor things
> like KASAN, UBSAN, etc that called dump_stack(). Regularize this line
> so CI systems and other things (like LKDTM) that depend on parsing
> "Call trace:" out of dmesg will see it for ARM.
>
> Before this patch:
>
>         UBSAN: array-index-out-of-bounds in ../drivers/misc/lkdtm/bugs.c:=
376:16
>         index 8 is out of range for type 'char [8]'
>         CPU: 0 PID: 1402 Comm: cat Not tainted 6.7.0-rc2 #1
>         Hardware name: Generic DT based system
>          dump_backtrace from show_stack+0x20/0x24
>          r7:00000042 r6:00000000 r5:60070013 r4:80cf5d7c
>          show_stack from dump_stack_lvl+0x88/0x98
>          dump_stack_lvl from dump_stack+0x18/0x1c
>          r7:00000042 r6:00000008 r5:00000008 r4:80fab118
>          dump_stack from ubsan_epilogue+0x10/0x3c
>          ubsan_epilogue from __ubsan_handle_out_of_bounds+0x80/0x84
>         ...
>
> After this patch:
>
>         UBSAN: array-index-out-of-bounds in ../drivers/misc/lkdtm/bugs.c:=
376:16
>         index 8 is out of range for type 'char [8]'
>         CPU: 0 PID: 1402 Comm: cat Not tainted 6.7.0-rc2 #1
>         Hardware name: Generic DT based system
>         Call trace:
>          dump_backtrace from show_stack+0x20/0x24
>          r7:00000042 r6:00000000 r5:60070013 r4:80cf5d7c
>          show_stack from dump_stack_lvl+0x88/0x98
>          dump_stack_lvl from dump_stack+0x18/0x1c
>          r7:00000042 r6:00000008 r5:00000008 r4:80fab118
>          dump_stack from ubsan_epilogue+0x10/0x3c
>          ubsan_epilogue from __ubsan_handle_out_of_bounds+0x80/0x84
>         ...
>
> Reported-by: Mark Brown <broonie@kernel.org>
> Cc: Russell King <linux@armlinux.org.uk>
> Cc: Ard Biesheuvel <ardb@kernel.org>
> Cc: Arnd Bergmann <arnd@arndb.de>
> Cc: Linus Walleij <linus.walleij@linaro.org>
> Cc: Vladimir Murzin <vladimir.murzin@arm.com>
> Cc: Zhen Lei <thunder.leizhen@huawei.com>
> Cc: Keith Packard <keithpac@amazon.com>
> Cc: Haibo Li <haibo.li@mediatek.com>
> Cc: linux-arm-kernel@lists.infradead.org
> Signed-off-by: Kees Cook <keescook@chromium.org>

Makes sense.
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>

Yours,
Linus Walleij