From 8f5bc2abfd4240b1f55425a3d36b6e6c391bc148 Mon Sep 17 00:00:00 2001 From: Jiri Slaby Date: Tue, 1 Mar 2011 17:41:10 +0100 Subject: [CPUFREQ] fix BUG on cpufreq policy init failure cpufreq_register_driver sets cpufreq_driver to a structure owned (and placed) in the caller's memory. If cpufreq policy fails in its ->init function, sysdev_driver_register returns nonzero in cpufreq_register_driver. Now, cpufreq_register_driver returns an error without setting cpufreq_driver back to NULL. Usually cpufreq policy modules are unloaded because they propagate the error to the module init function and return that. So a later access to any member of cpufreq_driver causes bugs like: BUG: unable to handle kernel paging request at ffffffffa00270a0 IP: [] cpufreq_cpu_get+0x53/0xe0 PGD 1805067 PUD 1809063 PMD 1c3f90067 PTE 0 Oops: 0000 [#1] SMP last sysfs file: /sys/devices/virtual/net/tun0/statistics/collisions CPU 0 Modules linked in: ... Pid: 5677, comm: thunderbird-bin Tainted: G W 2.6.38-rc4-mm1_64+ #1389 To be filled by O.E.M./To Be Filled By O.E.M. RIP: 0010:[] [] cpufreq_cpu_get+0x53/0xe0 RSP: 0018:ffff8801aec37d98 EFLAGS: 00010086 RAX: 0000000000000202 RBX: 0000000000000000 RCX: 0000000000000001 RDX: ffffffffa00270a0 RSI: 0000000000001000 RDI: ffffffff8199ece8 ... Call Trace: [] cpufreq_quick_get+0x10/0x30 [] show_cpuinfo+0x2ab/0x300 [] seq_read+0xf2/0x3f0 [] ? __strncpy_from_user+0x33/0x60 [] proc_reg_read+0x6d/0xa0 [] vfs_read+0xc3/0x180 [] sys_read+0x4c/0x90 [] system_call_fastpath+0x16/0x1b ... It's all cause by weird fail path handling in cpufreq_register_driver. To fix that, shuffle the code to do proper handling with gotos. Signed-off-by: Jiri Slaby Signed-off-by: Dave Jones --- drivers/cpufreq/cpufreq.c | 27 +++++++++++++++------------ 1 file changed, 15 insertions(+), 12 deletions(-) (limited to 'drivers/cpufreq') diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c index 1109f68..5cb4d09 100644 --- a/drivers/cpufreq/cpufreq.c +++ b/drivers/cpufreq/cpufreq.c @@ -1919,8 +1919,10 @@ int cpufreq_register_driver(struct cpufreq_driver *driver_data) ret = sysdev_driver_register(&cpu_sysdev_class, &cpufreq_sysdev_driver); + if (ret) + goto err_null_driver; - if ((!ret) && !(cpufreq_driver->flags & CPUFREQ_STICKY)) { + if (!(cpufreq_driver->flags & CPUFREQ_STICKY)) { int i; ret = -ENODEV; @@ -1935,21 +1937,22 @@ int cpufreq_register_driver(struct cpufreq_driver *driver_data) if (ret) { dprintk("no CPU initialized for driver %s\n", driver_data->name); - sysdev_driver_unregister(&cpu_sysdev_class, - &cpufreq_sysdev_driver); - - spin_lock_irqsave(&cpufreq_driver_lock, flags); - cpufreq_driver = NULL; - spin_unlock_irqrestore(&cpufreq_driver_lock, flags); + goto err_sysdev_unreg; } } - if (!ret) { - register_hotcpu_notifier(&cpufreq_cpu_notifier); - dprintk("driver %s up and running\n", driver_data->name); - cpufreq_debug_enable_ratelimit(); - } + register_hotcpu_notifier(&cpufreq_cpu_notifier); + dprintk("driver %s up and running\n", driver_data->name); + cpufreq_debug_enable_ratelimit(); + return 0; +err_sysdev_unreg: + sysdev_driver_unregister(&cpu_sysdev_class, + &cpufreq_sysdev_driver); +err_null_driver: + spin_lock_irqsave(&cpufreq_driver_lock, flags); + cpufreq_driver = NULL; + spin_unlock_irqrestore(&cpufreq_driver_lock, flags); return ret; } EXPORT_SYMBOL_GPL(cpufreq_register_driver); -- cgit v1.1