From: Oleg Nesterov <oleg@redhat.com>
Date: Tue, 23 Jun 2009 19:25:32 +0000 (+0200)
Subject: mm_for_maps: simplify, use ptrace_may_access()
X-Git-Tag: v2.6.31-rc6~23^2~2
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=13f0feafa6b8aead57a2a328e2fca6a5828bf286;p=pandora-kernel.git

mm_for_maps: simplify, use ptrace_may_access()

It would be nice to kill __ptrace_may_access(). It requires task_lock(),
but this lock is only needed to read mm->flags in the middle.

Convert mm_for_maps() to use ptrace_may_access(), this also simplifies
the code a little bit.

Also, we do not need to take ->mmap_sem in advance. In fact I think
mm_for_maps() should not play with ->mmap_sem at all, the caller should
take this lock.

With or without this patch, without ->cred_guard_mutex held we can race
with exec() and get the new ->mm but check old creds.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Reviewed-by: Serge Hallyn <serue@us.ibm.com>
Signed-off-by: James Morris <jmorris@namei.org>
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