Date: Thu, 16 Sep 2010 14:51:55 +0900 (JST) From: KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com> To: Linus Torvalds <torvalds@...ux-foundation.org> Cc: kosaki.motohiro@...fujitsu.com, Roland McGrath <roland@...hat.com>, 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>, KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com> Subject: Re: [PATCH 2/2] execve: check the VM has enough memory at first > > On Wed, Sep 8, 2010 at 10:04 PM, KOSAKI Motohiro > > <kosaki.motohiro@...fujitsu.com> wrote: > > > > > > After this patch, execve() expand stack at first and receive to > > > check vm_enough_memory() properly. then, too long argument of > > > execve() than the machine memory return EFAULT properly. > > > > This is horrible. We don't want to walk the arguments one more time > > just for this. Let's just improve the checks that we do as we go > > along. > > > > Linus > > Okey. I'll consider new way in this night. After while thinking, I decided to just drop this idea. because 1) If one pass check is must, we can't reuse vm-overcommit check. 2) Glibc has the duplicated hueristic, then we can't change it nor introduce new hard limit. (Sh*t) 3) This is not must fix, it only mitigate a pain when accidental large argv case. Only OOM fixes enough care intended attack case. 4) distro can change default of rlim_max of RLIMIT_STACK. It protect from RLIM_INFINITY smash. Briefly says, to introduce new limit has bad benefit/risk balance. Sadly.
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