linux-kernel - Re: [PATCH 1/3] setup_arg_pages: diagnose excessive argument size

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]

Date:	Thu,  9 Sep 2010 14:31:18 +0900 (JST)
From:	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
To:	Brad Spengler <spender@...ecurity.net>
Cc:	kosaki.motohiro@...fujitsu.com, Roland McGrath <roland@...hat.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org, oss-security@...ts.openwall.com,
	Solar Designer <solar@...nwall.com>,
	Kees Cook <kees.cook@...onical.com>,
	Al Viro <viro@...iv.linux.org.uk>,
	Oleg Nesterov <oleg@...hat.com>,
	Neil Horman <nhorman@...driver.com>,
	linux-fsdevel@...r.kernel.org, pageexec@...email.hu,
	"Brad Spengler <spender@...ecurity.net> Eugene Teo" 
	<eugene@...hat.com>
Subject: Re: [PATCH 1/3] setup_arg_pages: diagnose excessive argument size

> I still don't think this addresses the whole problem.  Without question,
> the rlimit / 4 check is bogus.  If nobody agrees with the intent of that 
> check, then it should be removed, but I think the better solution is to 
> fix the check so that it matches its original intent: let the initial 
> stack setup be up to 1/Xth of the min(rlimit, TASK_SIZE dependent upon 
> personality), which allows space for additional stack setup in the ELF 
> loader and then further growth once the process is live.  If that 
> amount is overstepped, then the exec will return an error to the calling 
> process instead of being terminated.
> 
> It might be useful to consult with the people who introduced/approved 
> the check in the first place, as they seemed to have reasons for 
> implementing it.

Brad, sorry, I have bad news. glibc sysconf(_SC_ARG_MAX) is implemented
by hard coded RLIMIT_STACK/4 heuristics. That said, at least _now_, we
can't change this even though you disliked. That said, we can't break
userland even though userland library is very crazy.

I don't dislike your "1/Xth of the min(rlimit, TASK_SIZE dependent upon 
> personality)" idea. however I think You and Roland haven't agreed this
point yet. he seems to want "unlimited" works as "unlimited". then, now
I don't make such patch. Instead, I would propose to insert 
__vm_enough_memory() check in execve() pass. It prevent almost argv attack.



--
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/