From: Oleg Nesterov <oleg@redhat.com>
To: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Michal Hocko <mhocko@suse.cz>, Sergey Dyasly <dserrg@gmail.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 4/4] proc: avoid ->f_pos overflows in proc_task_readdir() paths
Date: Tue, 4 Jun 2013 19:14:35 +0200 [thread overview]
Message-ID: <20130604171435.GA20416@redhat.com> (raw)
In-Reply-To: <877giarg81.fsf@xmission.com>
On 06/03, Eric W. Biederman wrote:
>
> Oleg Nesterov <oleg@redhat.com> writes:
>
> > 1. proc_task_readdir() truncates f_pos to long, this can lead
> > to wrong result on 32bit.
> >
> This won't compile on some 32bit architectures like x86-32.
>
> switch(unsigned long long) requires helpers that the kernel does not
> included. Or at least the kernel has not included because such code
> is a problem. In fact that is the reason Linus put the case to
> unsigned long in there.
Hmm, ee568b25, suprise... I am wondering if the kernel still supports
the compilers which needs __cmpdi2 in this case...
But this doesn't matter. The patch should not blindly revert ee568b25,
thanks!
> There is another bug in here as well that we may return really crazy
> things in the case of seek simultaneous with readdir.
i_mutex? both vfs_readdir() and default_llseek() take it... Anyway, this
is another issue.
> I think we really need to put f_pos
> in a local variable.
Heh. I swear, this is what I did initially. But I was afraid you will
blame this change as "overcomplicated" ;)
OK, I'll redo/resend this one later.
Oleg.
next prev parent reply other threads:[~2013-06-04 17:18 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-06-03 19:06 [PATCH v2 0/4] proc: first_tid() fix/cleanup Oleg Nesterov
2013-06-03 19:06 ` [PATCH v2 1/4] proc: first_tid: fix the potential use-after-free Oleg Nesterov
2013-06-03 19:07 ` [PATCH v2 2/4] proc: change first_tid() to use while_each_thread() Oleg Nesterov
2013-06-03 19:07 ` [PATCH v2 3/4] proc: simplify proc_task_readdir/first_tid paths Oleg Nesterov
2013-06-03 22:06 ` Eric W. Biederman
2013-06-03 19:07 ` [PATCH v2 4/4] proc: avoid ->f_pos overflows in proc_task_readdir() paths Oleg Nesterov
2013-06-03 22:18 ` Eric W. Biederman
2013-06-04 17:14 ` Oleg Nesterov [this message]
2013-06-04 17:39 ` Al Viro
2013-06-04 19:57 ` Oleg Nesterov
2013-06-04 21:06 ` Al Viro
2013-06-04 0:58 ` Al Viro
2013-06-04 17:35 ` Oleg Nesterov
2013-06-04 17:32 ` [PATCH v2 0/4] proc: first_tid() fix/cleanup Oleg Nesterov
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