From: Oleg Nesterov <oleg@redhat.com>
To: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Hugh Dickins <hugh@veritas.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
Andrew Morton <akpm@linux-foundation.org>,
Joe Malicki <jmalicki@metacarta.com>,
Michael Itz <mitz@metacarta.com>,
Kenneth Baker <bakerk@metacarta.com>,
Chris Wright <chrisw@sous-sol.org>,
David Howells <dhowells@redhat.com>,
Alexey Dobriyan <adobriyan@gmail.com>,
Greg Kroah-Hartman <gregkh@suse.de>,
linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: Q: check_unsafe_exec() races (Was: [PATCH 2/4] fix setuid sometimes doesn't)
Date: Mon, 30 Mar 2009 03:40:40 +0200 [thread overview]
Message-ID: <20090330014040.GA4807@redhat.com> (raw)
In-Reply-To: <20090330013612.GA4080@redhat.com>
On 03/30, Oleg Nesterov wrote:
>
> On 03/30, Al Viro wrote:
> >
> > On Mon, Mar 30, 2009 at 02:08:43AM +0100, Al Viro wrote:
> >
> > > So...
> > > * check_unsafe_exec() locks current->fs shared, goes through all
> > > threads comparing their ->fs with our, if the number doesn't match - bail
> > > out. Otherwise we mark it "under exec".
>
> Unless I missed something again, check_unsafe_exec() should check "under exec"
> after it takes fs->lock. If set - we are racing with sub-thread, return -EAGAIN.
>
> We can't proceed. If that another exec() fails, it will clear "under exec" at
> the end of do_execve(), before we kill other threads.
Or we need a counter to mark/unmark.
Oleg.
next prev parent reply other threads:[~2009-03-30 1:46 UTC|newest]
Thread overview: 50+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-03-28 23:16 [PATCH 1/4] compat_do_execve should unshare_files Hugh Dickins
2009-03-28 23:20 ` [PATCH 2/4] fix setuid sometimes doesn't Hugh Dickins
2009-03-29 0:53 ` Q: check_unsafe_exec() races (Was: [PATCH 2/4] fix setuid sometimes doesn't) Oleg Nesterov
2009-03-29 4:10 ` Al Viro
2009-03-29 4:14 ` Al Viro
2009-03-29 4:52 ` Oleg Nesterov
2009-03-29 5:55 ` Al Viro
2009-03-29 6:01 ` Al Viro
2009-03-29 21:36 ` Oleg Nesterov
2009-03-29 22:20 ` Al Viro
2009-03-29 23:56 ` Oleg Nesterov
2009-03-30 0:03 ` Oleg Nesterov
2009-03-30 1:08 ` Al Viro
2009-03-30 1:13 ` Al Viro
2009-03-30 1:36 ` Oleg Nesterov
2009-03-30 1:40 ` Oleg Nesterov [this message]
2009-03-30 12:31 ` Al Viro
2009-03-30 14:32 ` Hugh Dickins
2009-03-31 6:16 ` Al Viro
2009-04-01 0:28 ` Hugh Dickins
2009-04-01 2:38 ` Al Viro
2009-04-01 3:03 ` Al Viro
2009-04-01 11:25 ` Hugh Dickins
2009-04-06 15:31 ` Oleg Nesterov
2009-04-19 16:30 ` Hugh Dickins
2009-04-21 16:10 ` Oleg Nesterov
2009-04-21 16:31 ` Linus Torvalds
2009-04-21 17:15 ` Oleg Nesterov
2009-04-21 17:35 ` Linus Torvalds
2009-04-21 19:39 ` Hugh Dickins
2009-04-23 23:01 ` [PATCH 1/2] do_execve() must not clear fs->in_exec if it was set by another thread Oleg Nesterov
2009-04-23 23:18 ` Roland McGrath
2009-04-23 23:31 ` Al Viro
2009-04-24 11:57 ` [PATCH 3/2] check_unsafe_exec: rcu_read_unlock Hugh Dickins
2009-04-24 14:34 ` Oleg Nesterov
2009-04-24 4:20 ` [PATCH 1/2] do_execve() must not clear fs->in_exec if it was set by another thread Hugh Dickins
2009-04-23 23:02 ` [PATCH 2/2] check_unsafe_exec: s/lock_task_sighand/rcu_read_lock/ Oleg Nesterov
2009-04-23 23:18 ` Roland McGrath
2009-04-24 4:29 ` Hugh Dickins
2009-04-01 11:18 ` Q: check_unsafe_exec() races (Was: [PATCH 2/4] fix setuid sometimes doesn't) Hugh Dickins
2009-04-06 15:51 ` Oleg Nesterov
2009-04-19 16:44 ` Hugh Dickins
2009-04-21 16:39 ` Oleg Nesterov
2009-03-30 23:45 ` Serge E. Hallyn
2009-03-31 6:19 ` Al Viro
2009-03-28 23:21 ` [PATCH 3/4] fix setuid sometimes wouldn't Hugh Dickins
2009-03-29 11:19 ` Alexey Dobriyan
2009-03-29 21:48 ` Oleg Nesterov
2009-03-29 22:37 ` Al Viro
2009-03-28 23:23 ` [PATCH 4/4] Annotate struct fs_struct's usage count restriction Hugh Dickins
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