linux-kernel - Re: [PATCH] sh: Replace all non-returning strlcpy with strscpy

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Message-ID: <63d247d3de5a0ca289c39dff930f83d7bbc7c4a5.camel@physik.fu-berlin.de>
Date:   Wed, 14 Jun 2023 21:22:31 +0200
From:   John Paul Adrian Glaubitz <glaubitz@...sik.fu-berlin.de>
To:     Azeem Shaikh <azeemshaikh38@...il.com>,
        Yoshinori Sato <ysato@...rs.sourceforge.jp>,
        Rich Felker <dalias@...c.org>
Cc:     linux-hardening@...r.kernel.org, linux-sh@...r.kernel.org,
        linux-kernel@...r.kernel.org, Randy Dunlap <rdunlap@...radead.org>
Subject: Re: [PATCH] sh: Replace all non-returning strlcpy with strscpy

On Tue, 2023-05-30 at 16:30 +0000, Azeem Shaikh wrote:
> strlcpy() reads the entire source buffer first.
> This read may exceed the destination size limit.
> This is both inefficient and can lead to linear read
> overflows if a source string is not NUL-terminated [1].
> In an effort to remove strlcpy() completely [2], replace
> strlcpy() here with strscpy().
> No return values were used, so direct replacement is safe.
> 
> [1] https://www.kernel.org/doc/html/latest/process/deprecated.html#strlcpy
> [2] https://github.com/KSPP/linux/issues/89
> 
> Signed-off-by: Azeem Shaikh <azeemshaikh38@...il.com>
> ---
>  arch/sh/drivers/dma/dma-api.c |    2 +-
>  arch/sh/kernel/setup.c        |    4 ++--
>  2 files changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/sh/drivers/dma/dma-api.c b/arch/sh/drivers/dma/dma-api.c
> index ab9170494dcc..89cd4a3b4cca 100644
> --- a/arch/sh/drivers/dma/dma-api.c
> +++ b/arch/sh/drivers/dma/dma-api.c
> @@ -198,7 +198,7 @@ int request_dma(unsigned int chan, const char *dev_id)
>  	if (atomic_xchg(&channel->busy, 1))
>  		return -EBUSY;
>  
> -	strlcpy(channel->dev_id, dev_id, sizeof(channel->dev_id));
> +	strscpy(channel->dev_id, dev_id, sizeof(channel->dev_id));
>  
>  	if (info->ops->request) {
>  		result = info->ops->request(channel);
> diff --git a/arch/sh/kernel/setup.c b/arch/sh/kernel/setup.c
> index af977ec4ca5e..e4f0f9a1d355 100644
> --- a/arch/sh/kernel/setup.c
> +++ b/arch/sh/kernel/setup.c
> @@ -304,9 +304,9 @@ void __init setup_arch(char **cmdline_p)
>  	bss_resource.end = virt_to_phys(__bss_stop)-1;
>  
>  #ifdef CONFIG_CMDLINE_OVERWRITE
> -	strlcpy(command_line, CONFIG_CMDLINE, sizeof(command_line));
> +	strscpy(command_line, CONFIG_CMDLINE, sizeof(command_line));
>  #else
> -	strlcpy(command_line, COMMAND_LINE, sizeof(command_line));
> +	strscpy(command_line, COMMAND_LINE, sizeof(command_line));
>  #ifdef CONFIG_CMDLINE_EXTEND
>  	strlcat(command_line, " ", sizeof(command_line));
>  	strlcat(command_line, CONFIG_CMDLINE, sizeof(command_line));

Tested-by: John Paul Adrian Glaubitz <glaubitz@...sik.fu-berlin.de>

-- 
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: :' :  Debian Developer
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