linux-hardening - Re: [PATCH v3] drivers/edac/edac

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Date:   Sat, 07 Aug 2021 10:09:35 -0700
From:   Joe Perches <joe@...ches.com>
To:     Len Baker <len.baker@....com>, Borislav Petkov <bp@...en8.de>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Tony Luck <tony.luck@...el.com>,
        James Morse <james.morse@....com>,
        Robert Richter <rric@...nel.org>
Cc:     Kees Cook <keescook@...omium.org>, linux-hardening@...r.kernel.org,
        linux-edac@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3] drivers/edac/edac_mc: Remove all strcpy() uses

On Sat, 2021-08-07 at 17:59 +0200, Len Baker wrote:
> strcpy() performs no bounds checking on the destination buffer. This
> could result in linear overflows beyond the end of the buffer, leading
> to all kinds of misbehaviors. The safe replacement is strscpy().

Probably better to change the commit subject to something like
what is generally used by the subsystem.

Maybe:
	EDAC/mc: Convert strcpy to strscpy
or
	EDAC/mc: Prefer strscpy over strcpy

and also:

> diff --git a/drivers/edac/edac_mc.c b/drivers/edac/edac_mc.c
[]
> @@ -1113,11 +1115,11 @@ void edac_mc_handle_error(const enum hw_event_mc_err_type type,
>  			p = e->label;
>  			*p = '\0';
>  		} else {
> -			if (p != e->label) {
> -				strcpy(p, OTHER_LABEL);
> -				p += strlen(OTHER_LABEL);
> -			}
> -			strcpy(p, dimm->label);
> +			const char *text = (p != e->label) ? OTHER_LABEL :
> +				dimm->label;
> +
> +			strscpy(p, text, len);
> +			len -= strlen(p);
>  			p += strlen(p);

Perhaps this should use scnprintf rather than strscpy
Something like:
			n += scnprintf(buf + n, len - n, "%s",
				       p == e->label ? dim->label : OTHER_LABEL);