linux-hardening - Re: [PATCH] tracing/uprobe: Replace strlcpy() with strscpy()

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Message-Id: <20231201145129.30fcaf1b762a9b496ac44a2f@kernel.org>
Date: Fri, 1 Dec 2023 14:51:29 +0900
From: Masami Hiramatsu (Google) <mhiramat@...nel.org>
To: Kees Cook <keescook@...omium.org>
Cc: Steven Rostedt <rostedt@...dmis.org>, Masami Hiramatsu
 <mhiramat@...nel.org>, linux-trace-kernel@...r.kernel.org,
 linux-kernel@...r.kernel.org, linux-hardening@...r.kernel.org
Subject: Re: [PATCH] tracing/uprobe: Replace strlcpy() with strscpy()

On Thu, 30 Nov 2023 12:56:08 -0800
Kees Cook <keescook@...omium.org> 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].
> Additionally, it returns the size of the source string, not the
> resulting size of the destination string. In an effort to remove strlcpy()
> completely[2], replace strlcpy() here with strscpy().
> 
> The negative return value is already handled by this code so no new
> handling is needed here.
> 
> Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strlcpy [1]
> Link: https://github.com/KSPP/linux/issues/89 [2]
> Cc: Steven Rostedt <rostedt@...dmis.org>
> Cc: Masami Hiramatsu <mhiramat@...nel.org>
> Cc: linux-trace-kernel@...r.kernel.org
> Signed-off-by: Kees Cook <keescook@...omium.org>

Thanks for reporting! Let me pick this.

Thanks!

> ---
>  kernel/trace/trace_uprobe.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/kernel/trace/trace_uprobe.c b/kernel/trace/trace_uprobe.c
> index 99c051de412a..a84b85d8aac1 100644
> --- a/kernel/trace/trace_uprobe.c
> +++ b/kernel/trace/trace_uprobe.c
> @@ -151,7 +151,7 @@ fetch_store_string(unsigned long addr, void *dest, void *base)
>  		return -ENOMEM;
>  
>  	if (addr == FETCH_TOKEN_COMM)
> -		ret = strlcpy(dst, current->comm, maxlen);
> +		ret = strscpy(dst, current->comm, maxlen);
>  	else
>  		ret = strncpy_from_user(dst, src, maxlen);
>  	if (ret >= 0) {
> -- 
> 2.34.1
> 


-- 
Masami Hiramatsu (Google) <mhiramat@...nel.org>