linux-kernel - Re: [PATCH v2] kdb: Replace deprecated strcpy() with memmove() in vkdb

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Message-ID: <CAD=FV=VnvUUG7qE_RDKfos1H-baZUT8V5vKx2QNRX14OZ0QnwA@mail.gmail.com>
Date: Tue, 12 Aug 2025 09:24:55 -0700
From: Doug Anderson <dianders@...omium.org>
To: Thorsten Blum <thorsten.blum@...ux.dev>
Cc: Jason Wessel <jason.wessel@...driver.com>, Daniel Thompson <danielt@...nel.org>, 
	Justin Stitt <justinstitt@...gle.com>, linux-hardening@...r.kernel.org, 
	Daniel Thompson <daniel@...cstar.com>, kgdb-bugreport@...ts.sourceforge.net, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] kdb: Replace deprecated strcpy() with memmove() in vkdb_printf()

Hi,

On Tue, Aug 12, 2025 at 6:27 AM Thorsten Blum <thorsten.blum@...ux.dev> wrote:
>
> strcpy() is deprecated and its behavior is undefined when the source and
> destination buffers overlap. Use memmove() instead to avoid any
> undefined behavior.
>
> Adjust comments for clarity.
>
> Link: https://github.com/KSPP/linux/issues/88
> Signed-off-by: Thorsten Blum <thorsten.blum@...ux.dev>
> ---
> Changes in v2:
> - Use memmove() because of strcpy()'s undefined behavior with
>   overlapping buffers as suggested by Doug Anderson
> - Compile-tested only
> - Link to v1: https://lore.kernel.org/lkml/20250811170351.68985-1-thorsten.blum@linux.dev/
> ---
>  kernel/debug/kdb/kdb_io.c | 14 ++++++++------
>  1 file changed, 8 insertions(+), 6 deletions(-)

Much nicer, thank you!

Given that the old code was officially relying on undefined behavior
of strcpy() before, I'd personally even add:

Fixes: 5d5314d6795f ("kdb: core for kgdb back end (1 of 2)")

In any case:

Reviewed-by: Douglas Anderson <dianders@...omium.org>