linux-kernel - Re: [PATCH] libbpf: Replace strcpy() with memcpy() in bpf_object_

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Message-ID: <2025071756-motor-slackness-ef0d@gregkh>
Date: Thu, 17 Jul 2025 19:09:26 +0200
From: Greg KH <gregkh@...uxfoundation.org>
To: Suchit K <suchitkarunakaran@...il.com>
Cc: Yonghong Song <yonghong.song@...ux.dev>, ast@...nel.org,
	daniel@...earbox.net, andrii@...nel.org, martin.lau@...ux.dev,
	eddyz87@...il.com, song@...nel.org, john.fastabend@...il.com,
	kpsingh@...nel.org, sdf@...ichev.me, haoluo@...gle.com,
	jolsa@...nel.org, bpf@...r.kernel.org, skhan@...uxfoundation.org,
	linux-kernel-mentees@...ts.linux.dev, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] libbpf: Replace strcpy() with memcpy() in
 bpf_object__new()

On Thu, Jul 17, 2025 at 10:29:50PM +0530, Suchit K wrote:
> On Thu, 17 Jul 2025 at 22:19, Yonghong Song <yonghong.song@...ux.dev> wrote:
> >
> >
> >
> > On 7/17/25 4:59 AM, Suchit Karunakaran wrote:
> > > Replace the unsafe strcpy() call with memcpy() when copying the path
> > > into the bpf_object structure. Since the memory is pre-allocated to
> > > exactly strlen(path) + 1 bytes and the length is already known, memcpy()
> > > is safer than strcpy().
> >
> > I don't understand in this particular context why strcpy()
> > is less safer than memcpy(). Both of them will achieve the
> > exactly same goal.
> >
> 
> Sorry, I meant that strcpy() is generally considered unsafe because it
> doesn't perform bounds checking. Its use is deprecated and
> discouraged, as noted in Documentation/process/deprecated.rst. I made
> this change with that in mind, although I'm not entirely certain
> whether it's actually unsafe in this specific context.
> 

Your change also did not do any bounds checking at all, so how is this
now safer?

confused,

greg k-h