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Revision 35a9393c95b31870a74f51a3e7455f33f5657b6f authored by Peter Zijlstra on 26 February 2015, 15:23:11 UTC, committed by Ingo Molnar on 23 March 2015, 09:49:07 UTC 
lockdep: Fix the module unload key range freeing logic
 
Module unload calls lockdep_free_key_range(), which removes entries
from the data structures. Most of the lockdep code OTOH assumes the
data structures are append only; in specific see the comments in
add_lock_to_list() and look_up_lock_class().

Clearly this has only worked by accident; make it work proper. The
actual scenario to make it go boom would involve the memory freed by
the module unlock being re-allocated and re-used for a lock inside of
a rcu-sched grace period. This is a very unlikely scenario, still
better plug the hole.

Use RCU list iteration in all places and ammend the comments.

Change lockdep_free_key_range() to issue a sync_sched() between
removal from the lists and returning -- which results in the memory
being freed. Further ensure the callers are placed correctly and
comment the requirements.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andrey Tsyvarev <tsyvarev@ispras.ru>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
1 parent bc465aa
Raw File
fips.c 
/*
 * FIPS 200 support.
 *
 * Copyright (c) 2008 Neil Horman <nhorman@tuxdriver.com>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the Free
 * Software Foundation; either version 2 of the License, or (at your option)
 * any later version.
 *
 */

#include "internal.h"

int fips_enabled;
EXPORT_SYMBOL_GPL(fips_enabled);

/* Process kernel command-line parameter at boot time. fips=0 or fips=1 */
static int fips_enable(char *str)
{
	fips_enabled = !!simple_strtol(str, NULL, 0);
	printk(KERN_INFO "fips mode: %s\n",
		fips_enabled ? "enabled" : "disabled");
	return 1;
}

__setup("fips=", fips_enable);
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