linux-kernel - Re: [PATCH] cred: remove const qualifiers

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20080819003211.ba6b0ac5.akpm@linux-foundation.org>
Date:	Tue, 19 Aug 2008 00:32:11 -0700
From:	Andrew Morton <akpm@...ux-foundation.org>
To:	David Howells <dhowells@...hat.com>
Cc:	Harvey Harrison <harvey.harrison@...il.com>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] cred: remove const qualifiers

On Sun, 10 Aug 2008 11:58:36 +0100 David Howells <dhowells@...hat.com> wrote:

> Harvey Harrison <harvey.harrison@...il.com> wrote:
> 
> > get_new_cred clearly writes through the pointer, so const isn't
> > appropriate.  Sparse warns thusly:
> > 
> > include/linux/cred.h: In function ___get_cred___:
> > include/linux/cred.h:181: warning: passing argument 1 of ___get_new_cred___ discards qualifiers from pointer target type
> 
> Sparse is wrong in this instance, it failed to note the cast.  I know what I'm
> doing.

Nobody who reads the code will know what you were doing - the code
looks plain wrong.

> > -static inline const struct cred *get_cred(const struct cred *cred)
> > +static inline struct cred *get_cred(struct cred *cred)
> 
> That will break the compilation.  Please don't do that.
> 
> The point of my use of const in this instance is to stop people from trying to
> modify committed credentials directly, especially current->cred.  But we still
> have to be able to take a reference to it.  Unfortunately, C does not provide
> the necessary tools to do what I want.
> 
> Eventually, we can probably ditch the const marks on the pointers but not yet.

That information should have been included in a code comment.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/