From: Oleg Nesterov <oleg@redhat.com>
Date: Wed, 26 May 2010 21:42:53 +0000 (-0700)
Subject: ptrace: PTRACE_GETFDPIC: fix the unsafe usage of child->mm
X-Git-Tag: v2.6.35-rc1~185
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=e0129ef91ed758c06b6557c36124acfb2e1c7305;p=pandora-kernel.git

ptrace: PTRACE_GETFDPIC: fix the unsafe usage of child->mm

Now that Mike Frysinger unified the FDPIC ptrace code, we can fix the
unsafe usage of child->mm in ptrace_request(PTRACE_GETFDPIC).

We have the reference to task_struct, and ptrace_check_attach() verified
the tracee is stopped.  But nothing can protect from SIGKILL after that,
we must not assume child->mm != NULL.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Mike Frysinger <vapier.adi@gmail.com>
Acked-by: David Howells <dhowells@redhat.com>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: Greg Ungerer <gerg@snapgear.com>
Acked-by: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---

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