linux-kernel - [PATCH] sched: missing locking in sched

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-ID: <20080427211224.GA21830@osiris.boeblingen.de.ibm.com>
Date:	Sun, 27 Apr 2008 23:12:24 +0200
From:	Heiko Carstens <heiko.carstens@...ibm.com>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Gautham R Shenoy <ego@...ibm.com>, Ingo Molnar <mingo@...e.hu>,
	Paul Jackson <pj@....com>, linux-kernel@...r.kernel.org
Subject: [PATCH] sched: missing locking in sched_domains code

From: Heiko Carstens <heiko.carstens@...ibm.com>

Concurrent calls to detach_destroy_domains and arch_init_sched_domains
were prevented by the old scheduler subsystem cpu hotplug mutex. When
this got converted to get_online_cpus() the locking got broken.
Unlike before now several processes can concurrently enter the critical
sections that were protected by the old lock.

So add a new sched_domains_mutex which protects these sections again.

Cc: Gautham R Shenoy <ego@...ibm.com>
Cc: Ingo Molnar <mingo@...e.hu>
Cc: Paul Jackson <pj@....com>
Signed-off-by: Heiko Carstens <heiko.carstens@...ibm.com>
---
 include/linux/sched.h |    2 ++
 kernel/cpuset.c       |    2 ++
 kernel/sched.c        |   11 +++++++++++
 3 files changed, 15 insertions(+)

Index: linux-2.6/kernel/sched.c
===================================================================
--- linux-2.6.orig/kernel/sched.c
+++ linux-2.6/kernel/sched.c
@@ -7807,14 +7807,23 @@ match2:
 	unlock_doms_cur();
 }
 
+/*
+ * Protects against concurrent calls to detach_destroy_domains
+ * and arch_init_sched_domains.
+ */
+DEFINE_MUTEX(sched_domains_mutex);
+
 #if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
 int arch_reinit_sched_domains(void)
 {
+	static DEFINE_MUTEX(arch_reinit_sched_domains_mutex);
 	int err;
 
 	get_online_cpus();
+	mutex_lock(&sched_domains_mutex);
 	detach_destroy_domains(&cpu_online_map);
 	err = arch_init_sched_domains(&cpu_online_map);
+	mutex_unlock(&sched_domains_mutex);
 	put_online_cpus();
 
 	return err;
@@ -7932,10 +7941,12 @@ void __init sched_init_smp(void)
 	BUG_ON(sched_group_nodes_bycpu == NULL);
 #endif
 	get_online_cpus();
+	mutex_lock(&sched_domains_mutex);
 	arch_init_sched_domains(&cpu_online_map);
 	cpus_andnot(non_isolated_cpus, cpu_possible_map, cpu_isolated_map);
 	if (cpus_empty(non_isolated_cpus))
 		cpu_set(smp_processor_id(), non_isolated_cpus);
+	mutex_unlock(&sched_domains_mutex);
 	put_online_cpus();
 	/* XXX: Theoretical race here - CPU may be hotplugged now */
 	hotcpu_notifier(update_sched_domains, 0);
Index: linux-2.6/include/linux/sched.h
===================================================================
--- linux-2.6.orig/include/linux/sched.h
+++ linux-2.6/include/linux/sched.h
@@ -809,6 +809,8 @@ struct sched_domain {
 #endif
 };
 
+extern struct mutex sched_domains_mutex;
+
 extern void partition_sched_domains(int ndoms_new, cpumask_t *doms_new,
 				    struct sched_domain_attr *dattr_new);
 extern int arch_reinit_sched_domains(void);
Index: linux-2.6/kernel/cpuset.c
===================================================================
--- linux-2.6.orig/kernel/cpuset.c
+++ linux-2.6/kernel/cpuset.c
@@ -684,7 +684,9 @@ restart:
 rebuild:
 	/* Have scheduler rebuild sched domains */
 	get_online_cpus();
+	mutex_lock(&sched_domains_mutex);
 	partition_sched_domains(ndoms, doms, dattr);
+	mutex_unlock(&sched_domains_mutex);
 	put_online_cpus();
 
 done:
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/