From: Len Baker <len.baker@gmx.com>
To: Joe Perches <joe@perches.com>
Cc: Len Baker <len.baker@gmx.com>, Borislav Petkov <bp@alien8.de>,
Mauro Carvalho Chehab <mchehab@kernel.org>,
Tony Luck <tony.luck@intel.com>,
James Morse <james.morse@arm.com>,
Robert Richter <rric@kernel.org>,
David Laight <David.Laight@ACULAB.COM>,
Kees Cook <keescook@chromium.org>,
linux-hardening@vger.kernel.org, linux-edac@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v5] EDAC/mc: Prefer strscpy or scnprintf over strcpy
Date: Fri, 3 Sep 2021 16:21:46 +0200 [thread overview]
Message-ID: <20210903142146.GA1998@titan> (raw)
In-Reply-To: <7b6dc45194f28db52740c2a604550f6879dafe36.camel@perches.com>
Hi,
On Sun, Aug 29, 2021 at 09:38:37AM -0700, Joe Perches wrote:
> On Sun, 2021-08-29 at 18:15 +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() [1].
> >
> > However, to simplify and clarify the code, to concatenate labels use
> > the scnprintf() function. This way it is not necessary to check the
> > return value of strscpy (-E2BIG if the parameter count is 0 or the src
> > was truncated) since the scnprintf returns always the number of chars
> > written into the buffer. This function returns always a nul-terminated
> > string even if it needs to be truncated.
> []
> > diff --git a/drivers/edac/edac_mc.c b/drivers/edac/edac_mc.c
> []
> > @@ -1113,12 +1116,11 @@ 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);
> > - p += strlen(p);
> > + const char *or = (p != e->label) ? OTHER_LABEL : "";
> > +
> > + n = scnprintf(p, len, "%s%s", or, dimm->label);
> > + len -= n;
> > + p += n;
>
> A very common and intelligible mechanism for this is:
>
> const char *prefix = "";
> int n = 0;
> ...
> n += scnprintf(e->label + n, sizeof(e->label) - n,
> "%s%s", prefix, dimm->label);
> prefix = " or ";
>
Ok, I will send a new version using this common mechanism. Thanks for the
advise.
Regards,
Len
prev parent reply other threads:[~2021-09-03 14:22 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-29 16:15 [PATCH v5] EDAC/mc: Prefer strscpy or scnprintf over strcpy Len Baker
2021-08-29 16:38 ` Joe Perches
2021-09-03 14:21 ` Len Baker [this message]
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