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247bc03742
linux/kernel
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Rafael J. Wysocki 247bc03742 PM / Sleep: Mitigate race between the freezer and request_firmware() 
There is a race condition between the freezer and request_firmware()
such that if request_firmware() is run on one CPU and
freeze_processes() is run on another CPU and usermodehelper_disable()
called by it succeeds to grab umhelper_sem for writing before
usermodehelper_read_trylock() called from request_firmware()
acquires it for reading, the request_firmware() will fail and
trigger a WARN_ON() complaining that it was called at a wrong time.
However, in fact, it wasn't called at a wrong time and
freeze_processes() simply happened to be executed simultaneously.

To avoid this race, at least in some cases, modify
usermodehelper_read_trylock() so that it doesn't fail if the
freezing of tasks has just started and hasn't been completed yet.
Instead, during the freezing of tasks, it will try to freeze the
task that has called it so that it can wait until user space is
thawed without triggering the scary warning.

For this purpose, change usermodehelper_disabled so that it can
take three different values, UMH_ENABLED (0), UMH_FREEZING and
UMH_DISABLED.  The first one means that usermode helpers are
enabled, the last one means "hard disable" (i.e. the system is not
ready for usermode helpers to be used) and the second one
is reserved for the freezer.  Namely, when freeze_processes() is
started, it sets usermodehelper_disabled to UMH_FREEZING which
tells usermodehelper_read_trylock() that it shouldn't fail just
yet and should call try_to_freeze() if woken up and cannot
return immediately.  This way all freezable tasks that happen
to call request_firmware() right before freeze_processes() is
started and lose the race for umhelper_sem with it will be
frozen and will sleep until thaw_processes() unsets
usermodehelper_disabled.  [For the non-freezable callers of
request_firmware() the race for umhelper_sem against
freeze_processes() is unfortunately unavoidable.]

Reported-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: stable@vger.kernel.org
2012-03-28 23:30:28 +02:00
..
debug Fixes: 2012-03-23 09:29:44 -07:00
events Merge branch 'for-3.4' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup 2012-03-20 18:11:21 -07:00
gcov gcov: disable CONSTRUCTORS for UML 2011-07-26 16:49:45 -07:00
irq Generialize powerpc's irq_host as irq_domain 2012-03-21 10:27:19 -07:00
power PM / Sleep: Mitigate race between the freezer and request_firmware() 2012-03-28 23:30:28 +02:00
sched Merge branch 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security 2012-03-21 13:25:04 -07:00
time Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input 2012-03-22 20:20:18 -07:00
trace Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2012-03-21 13:36:41 -07:00
.gitignore
acct.c Merge branch 'for-linus2' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2012-01-08 12:19:57 -08:00
async.c kernel/async: remove redundant declaration. 2012-01-13 09:32:18 +10:30
audit_tree.c audit_tree,rcu: Convert call_rcu(__put_tree) to kfree_rcu() 2011-07-20 14:10:11 -07:00
audit_watch.c
audit.c constify path argument of audit_log_d_path() 2012-03-20 21:29:40 -04:00
audit.h audit: remove AUDIT_SETUP_CONTEXT as it isn't used 2012-01-17 16:16:57 -05:00
auditfilter.c audit: allow interfield comparison in audit rules 2012-01-17 16:17:01 -05:00
auditsc.c kernel-doc: fix new warnings in auditsc.c 2012-01-23 08:44:53 -08:00
backtracetest.c
bounds.c memcg: remove direct page_cgroup-to-page pointer 2011-03-23 19:46:28 -07:00
capability.c Revert "capabitlies: ns_capable can use the cap helpers rather than lsm call" 2012-01-17 10:19:41 -08:00
cgroup_freezer.c cgroup: remove cgroup_subsys argument from callbacks 2012-02-02 09:20:22 -08:00
cgroup.c Merge branch 'akpm' (Andrew's patch-bomb) 2012-03-22 09:04:48 -07:00
compat.c kernel: Fix files explicitly needing EXPORT_SYMBOL infrastructure 2011-10-31 19:30:05 -04:00
configs.c kernel/configs.c: include MODULE_*() when CONFIG_IKCONFIG_PROC=n 2011-07-25 20:57:15 -07:00
cpu_pm.c cpu_pm: call notifiers during suspend 2011-09-23 12:05:29 +05:30
cpu.c Merge branch 'pm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm 2012-01-08 13:10:57 -08:00
cpuset.c cpuset: mm: reduce large amounts of memory barrier related damage v3 2012-03-21 17:54:59 -07:00
crash_dump.c Merge branch 'modsplit-Oct31_2011' of git://git.kernel.org/pub/scm/linux/kernel/git/paulg/linux 2011-11-06 19:44:47 -08:00
cred.c security: trim security.h 2012-02-14 10:45:42 +11:00
delayacct.c KVM: Steal time implementation 2011-07-14 12:59:14 +03:00
dma.c kernel: Map most files to use export.h instead of module.h 2011-10-31 09:20:12 -04:00
elfcore.c
exec_domain.c
exit.c kernel/exit.c: if init dies, log a signal which killed it, if any 2012-03-23 16:58:32 -07:00
extable.c extable, core_kernel_data(): Make sure all archs define _sdata 2011-05-20 08:56:56 +02:00
fork.c prctl: add PR_{SET,GET}_CHILD_SUBREAPER to allow simple process supervision 2012-03-23 16:58:32 -07:00
freezer.c PM / Freezer: Remove references to TIF_FREEZE in comments 2012-03-04 23:08:54 +01:00
futex_compat.c userns: user namespaces: convert several capable() calls 2011-03-23 19:47:08 -07:00
futex.c Merge branch 'core-locking-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2012-03-19 17:11:15 -07:00
groups.c kernel: Map most files to use export.h instead of module.h 2011-10-31 09:20:12 -04:00
hrtimer.c Merge branch 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2011-11-28 08:43:52 -08:00
hung_task.c hung_task: fix the broken rcu_lock_break() logic 2012-03-05 15:49:42 -08:00
irq_work.c kernel: fix two implicit header assumptions in irq_work.c 2011-10-31 09:20:12 -04:00
itimer.c [S390] cputime: add sparse checking and cleanup 2011-12-15 14:56:19 +01:00
jump_label.c static keys: Inline the static_key_enabled() function 2012-02-28 20:01:08 +01:00
kallsyms.c Merge branch 'core-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2011-03-25 17:52:22 -07:00
Kconfig.freezer
Kconfig.hz
Kconfig.locks arch:Kconfig.locks Remove unused config option. 2011-04-10 17:01:05 +02:00
Kconfig.preempt sched: Isolate preempt counting in its own config option 2011-06-10 15:15:40 +02:00
kexec.c PM / Sleep: Introduce "late suspend" and "early resume" of devices 2012-01-29 20:38:29 +01:00
kfifo.c kernel: Map most files to use export.h instead of module.h 2011-10-31 09:20:12 -04:00
kmod.c PM / Sleep: Mitigate race between the freezer and request_firmware() 2012-03-28 23:30:28 +02:00
kprobes.c kprobes: return proper error code from register_kprobe() 2012-03-05 15:49:42 -08:00
ksysfs.c kernel: ksysfs.c is implicitly using stat.h 2011-10-31 09:20:13 -04:00
kthread.c freezer: kill unused set_freezable_with_signal() 2011-11-23 09:28:17 -08:00
latencytop.c kernel: Map most files to use export.h instead of module.h 2011-10-31 09:20:12 -04:00
lockdep_internals.h
lockdep_proc.c kernel: Map most files to use export.h instead of module.h 2011-10-31 09:20:12 -04:00
lockdep_states.h
lockdep.c lockdep: Add CPU-idle/offline warning to lockdep-RCU splat 2012-02-21 09:06:06 -08:00
Makefile sysctl: Move the implementation into fs/proc/proc_sysctl.c 2012-01-24 16:37:54 -08:00
module.c error: implicit declaration of function 'module_flags_taint' 2012-01-15 16:21:07 -08:00
mutex-debug.c kernel: Map most files to use export.h instead of module.h 2011-10-31 09:20:12 -04:00
mutex-debug.h mutex: Use p->on_cpu for the adaptive spin 2011-04-14 08:52:33 +02:00
mutex.c sched/rt: Use schedule_preempt_disabled() 2012-03-01 10:28:03 +01:00
mutex.h mutex: Use p->on_cpu for the adaptive spin 2011-04-14 08:52:33 +02:00
notifier.c kernel: Map most files to use export.h instead of module.h 2011-10-31 09:20:12 -04:00
nsproxy.c kernel: Map most files to use export.h instead of module.h 2011-10-31 09:20:12 -04:00
padata.c padata: Fix race on sequence number wrap 2012-03-14 17:25:56 +08:00
panic.c panic: don't print redundant backtraces on oops 2012-01-12 20:13:11 -08:00
params.c includecheck: delete any duplicate instances of module.h 2012-02-28 19:31:56 -05:00
pid_namespace.c signal: zap_pid_ns_processes: s/SEND_SIG_NOINFO/SEND_SIG_FORCED/ 2012-03-23 16:58:41 -07:00
pid.c vfs: fix panic in __d_lookup() with high dentry hashtable counts 2012-02-13 20:45:38 -05:00
posix-cpu-timers.c [S390] cputime: add sparse checking and cleanup 2011-12-15 14:56:19 +01:00
posix-timers.c kernel: Map most files to use export.h instead of module.h 2011-10-31 09:20:12 -04:00
printk.c Merge branch 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2012-03-20 10:31:44 -07:00
profile.c kernel: Map most files to use export.h instead of module.h 2011-10-31 09:20:12 -04:00
ptrace.c ptrace: remove PTRACE_SEIZE_DEVEL bit 2012-03-23 16:58:41 -07:00
range.c range: fix bogus misuse of module.h to get printk() 2011-10-31 09:20:11 -04:00
rcu.h rcu: Allow nesting of rcu_idle_enter() and rcu_idle_exit() 2012-02-21 09:06:12 -08:00
rcupdate.c rcu: Check for illegal use of RCU from offlined CPUs 2012-02-21 09:06:03 -08:00
rcutiny_plugin.h rcu: Simplify unboosting checks 2012-02-21 09:03:43 -08:00
rcutiny.c rcu: Add RCU_NONIDLE() for idle-loop RCU read-side critical sections 2012-02-21 09:06:13 -08:00
rcutorture.c PTR_ERR should be called before its argument is cleared. 2012-02-21 09:06:10 -08:00
rcutree_plugin.h rcu: Hold off RCU_FAST_NO_HZ after timer posted 2012-02-21 09:42:30 -08:00
rcutree_trace.c rcu: Rework detection of use of RCU by offline CPUs 2012-02-21 09:06:07 -08:00
rcutree.c rcu: Stop spurious warnings from synchronize_sched_expedited 2012-02-21 15:33:34 -08:00
rcutree.h rcu: Rework detection of use of RCU by offline CPUs 2012-02-21 09:06:07 -08:00
relay.c relay: prevent integer overflow in relay_open() 2012-02-10 09:04:49 +01:00
res_counter.c net: introduce res_counter_charge_nofail() for socket allocations 2012-01-22 15:08:46 -05:00
resource.c kernel/resource.c: move EXPORT_SYMBOL right after definition 2012-02-03 23:37:07 +01:00
rtmutex_common.h
rtmutex-debug.c lockdep, rtmutex, bug: Show taint flags on error 2011-12-06 08:16:49 +01:00
rtmutex-debug.h
rtmutex-tester.c rtmutex-tester: convert sysdev_class to a regular subsystem 2011-12-14 14:54:22 -08:00
rtmutex.c Revert "rcu: Permit rt_mutex_unlock() with irqs disabled" 2011-12-11 10:33:18 -08:00
rtmutex.h
rwsem.c kernel: Map most files to use export.h instead of module.h 2011-10-31 09:20:12 -04:00
seccomp.c seccomp: audit abnormal end to a process due to seccomp 2012-01-17 16:16:55 -05:00
semaphore.c kernel: Map most files to use export.h instead of module.h 2011-10-31 09:20:12 -04:00
signal.c signal: cosmetic, s/from_ancestor_ns/force/ in prepare_signal() paths 2012-03-23 16:58:41 -07:00
smp.c kernel: Map most files to use export.h instead of module.h 2011-10-31 09:20:12 -04:00
softirq.c Merge branch 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2012-03-20 10:32:09 -07:00
spinlock.c kernel: Map most files to use export.h instead of module.h 2011-10-31 09:20:12 -04:00
srcu.c rcu: Call out dangers of expedited RCU primitives 2012-02-21 09:06:08 -08:00
stacktrace.c kernel: Map most files to use export.h instead of module.h 2011-10-31 09:20:12 -04:00
stop_machine.c Merge branch 'modsplit-Oct31_2011' of git://git.kernel.org/pub/scm/linux/kernel/git/paulg/linux 2011-11-06 19:44:47 -08:00
sys_ni.c Cross Memory Attach 2011-10-31 17:30:44 -07:00
sys.c prctl: add PR_{SET,GET}_CHILD_SUBREAPER to allow simple process supervision 2012-03-23 16:58:32 -07:00
sysctl_binary.c binary_sysctl(): fix memory leak 2011-12-20 10:25:04 -08:00
sysctl.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/sysctl 2012-03-23 18:08:58 -07:00
taskstats.c Make TASKSTATS require root access 2011-09-19 17:04:37 -07:00
test_kprobes.c
time.c kernel: Map most files to use export.h instead of module.h 2011-10-31 09:20:12 -04:00
timeconst.pl
timer.c Merge branch 'core-debugobjects-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2012-01-06 07:53:34 -08:00
tracepoint.c static keys: Introduce 'struct static_key', static_key_true()/false() and static_key_slow_[inc|dec]() 2012-02-24 10:05:59 +01:00
tsacct.c [S390] cputime: add sparse checking and cleanup 2011-12-15 14:56:19 +01:00
uid16.c userns: user namespaces: convert several capable() calls 2011-03-23 19:47:08 -07:00
up.c kernel: Map most files to use export.h instead of module.h 2011-10-31 09:20:12 -04:00
user_namespace.c kernel: Map most files to use export.h instead of module.h 2011-10-31 09:20:12 -04:00
user-return-notifier.c kernel: Map most files to use export.h instead of module.h 2011-10-31 09:20:12 -04:00
user.c kernel: Map most files to use export.h instead of module.h 2011-10-31 09:20:12 -04:00
utsname_sysctl.c Merge branch 'modsplit-Oct31_2011' of git://git.kernel.org/pub/scm/linux/kernel/git/paulg/linux 2011-11-06 19:44:47 -08:00
utsname.c kernel: Map most files to use export.h instead of module.h 2011-10-31 09:20:12 -04:00
wait.c lockdep/waitqueues: Add better annotation 2011-12-21 10:07:39 +01:00
watchdog.c kernel/watchdog.c: add comment to watchdog() exit path 2012-03-23 16:58:32 -07:00
workqueue_sched.h
workqueue.c Merge branch 'for-3.4' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq 2012-03-20 18:13:22 -07:00