From: Oleg Nesterov <oleg@redhat.com>
Date: Fri, 26 Jul 2013 17:25:40 +0000 (+0200)
Subject: tracing: Change event_filter_read/write to verify i_private != NULL
X-Git-Tag: v3.11-rc5~28^2~14
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=e2912b091c26b8ea95e5e00a43a7ac620f6c94a6;p=pandora-kernel.git

tracing: Change event_filter_read/write to verify i_private != NULL

event_filter_read/write() are racy, ftrace_event_call can be already
freed by trace_remove_event_call() callers.

1. Shift mutex_lock(event_mutex) from print/apply_event_filter to
   the callers.

2. Change the callers, event_filter_read() and event_filter_write()
   to read i_private under this mutex and abort if it is NULL.

This fixes nothing, but now we can change debugfs_remove("filter")
callers to nullify ->i_private and fix the the problem.

Link: http://lkml.kernel.org/r/20130726172540.GA3619@redhat.com

Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---

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