linux-kernel - Re: [PATCH 42/88] exec: use -ELOOP for max recursion depth

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] [day] [month] [year] [list]

Date:	Tue, 26 Mar 2013 13:25:04 -0700
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	Ben Hutchings <ben@...adent.org.uk>
Cc:	linux-kernel@...r.kernel.org, stable@...r.kernel.org,
	kernel-team@...ts.ubuntu.com, Kees Cook <keescook@...omium.org>,
	halfdog <me@...fdog.net>, P J P <ppandit@...hat.com>,
	Alexander Viro <viro@...iv.linux.org.uk>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Luis Henriques <luis.henriques@...onical.com>
Subject: Re: [PATCH 42/88] exec: use -ELOOP for max recursion depth

On Tue, Mar 19, 2013 at 02:53:07AM +0000, Ben Hutchings wrote:
> On Thu, 2013-03-14 at 10:35 +0000, Luis Henriques wrote:
> > 3.5.7.8 -stable review patch.  If anyone has any objections, please let me know.
> > 
> > ------------------
> > 
> > From: Kees Cook <keescook@...omium.org>
> > 
> > commit d740269867021faf4ce38a449353d2b986c34a67 upstream.
> > 
> > To avoid an explosion of request_module calls on a chain of abusive
> > scripts, fail maximum recursion with -ELOOP instead of -ENOEXEC. As soon
> > as maximum recursion depth is hit, the error will fail all the way back
> > up the chain, aborting immediately.
> > 
> > This also has the side-effect of stopping the user's shell from attempting
> > to reexecute the top-level file as a shell script. As seen in the
> > dash source:
> > 
> >         if (cmd != path_bshell && errno == ENOEXEC) {
> >                 *argv-- = cmd;
> >                 *argv = cmd = path_bshell;
> >                 goto repeat;
> >         }
> > 
> > The above logic was designed for running scripts automatically that lacked
> > the "#!" header, not to re-try failed recursion. On a legitimate -ENOEXEC,
> > things continue to behave as the shell expects.
> > 
> > Additionally, when tracking recursion, the binfmt handlers should not be
> > involved. The recursion being tracked is the depth of calls through
> > search_binary_handler(), so that function should be exclusively responsible
> > for tracking the depth.
> > 
> > Signed-off-by: Kees Cook <keescook@...omium.org>
> > Cc: halfdog <me@...fdog.net>
> > Cc: P J P <ppandit@...hat.com>
> > Cc: Alexander Viro <viro@...iv.linux.org.uk>
> > Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
> > Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org>
> > [ luis: backport to 3.5 ]
> > Signed-off-by: Luis Henriques <luis.henriques@...onical.com>
> [...]
> 
> Greg, I also included this in 3.2.y (commit 511d07b) but it is missing
> from 3.0.y and 3.4.y.  I hope one or other of these backports will be
> suitable for them (it was just a context fix for 3.2.y).

Applied, thanks.

greg k-h
--
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/