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authorSrinivas Pandruvada <srinivas.pandruvada@linux.intel.com>2015-10-07 13:50:43 -0700
committerRafael J. Wysocki <rafael.j.wysocki@intel.com>2015-10-08 21:47:13 +0200
commite25303676e18a7947185a34e26dd08cf0c0ea573 (patch)
tree807d723d722280a5fed31539de17e3b17cb844e8 /drivers/cpufreq/acpi-cpufreq.c
parent049e6dde7e57f0054fdc49102e7ef4830c698b46 (diff)
downloadleg-kernel-e25303676e18a7947185a34e26dd08cf0c0ea573.tar.gz
cpufreq: acpi_cpufreq: prevent crash on reading freqdomain_cpus
When freqdomain_cpus attribute is read from an offlined cpu, it will cause crash. This change prevents calling cpufreq_show_cpus when policy driver_data is NULL. Crash info: [ 170.814949] BUG: unable to handle kernel NULL pointer dereference at 0000000000000018 [ 170.814990] IP: [<ffffffff813b2490>] _find_next_bit.part.0+0x10/0x70 [ 170.815021] PGD 227d30067 PUD 229e56067 PMD 0 [ 170.815043] Oops: 0000 [#2] SMP [ 170.816022] CPU: 3 PID: 3121 Comm: cat Tainted: G D OE 4.3.0-rc3+ #33 ... ... [ 170.816657] Call Trace: [ 170.816672] [<ffffffff813b2505>] ? find_next_bit+0x15/0x20 [ 170.816696] [<ffffffff8160e47c>] cpufreq_show_cpus+0x5c/0xd0 [ 170.816722] [<ffffffffa031a409>] show_freqdomain_cpus+0x19/0x20 [acpi_cpufreq] [ 170.816749] [<ffffffff8160e65b>] show+0x3b/0x60 [ 170.816769] [<ffffffff8129b31c>] sysfs_kf_seq_show+0xbc/0x130 [ 170.816793] [<ffffffff81299be3>] kernfs_seq_show+0x23/0x30 [ 170.816816] [<ffffffff81240f2c>] seq_read+0xec/0x390 [ 170.816837] [<ffffffff8129a64a>] kernfs_fop_read+0x10a/0x160 [ 170.816861] [<ffffffff8121d9b7>] __vfs_read+0x37/0x100 [ 170.816883] [<ffffffff813217c0>] ? security_file_permission+0xa0/0xc0 [ 170.816909] [<ffffffff8121e2e3>] vfs_read+0x83/0x130 [ 170.816930] [<ffffffff8121f035>] SyS_read+0x55/0xc0 ... ... [ 170.817185] ---[ end trace bc6eadf82b2b965a ]--- Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Cc: 4.2+ <stable@vger.kernel.org> # 4.2+ Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Diffstat (limited to 'drivers/cpufreq/acpi-cpufreq.c')
-rw-r--r--drivers/cpufreq/acpi-cpufreq.c3
1 files changed, 3 insertions, 0 deletions
diff --git a/drivers/cpufreq/acpi-cpufreq.c b/drivers/cpufreq/acpi-cpufreq.c
index 798277227de7..cec1ee2d2f74 100644
--- a/drivers/cpufreq/acpi-cpufreq.c
+++ b/drivers/cpufreq/acpi-cpufreq.c
@@ -149,6 +149,9 @@ static ssize_t show_freqdomain_cpus(struct cpufreq_policy *policy, char *buf)
{
struct acpi_cpufreq_data *data = policy->driver_data;
+ if (unlikely(!data))
+ return -ENODEV;
+
return cpufreq_show_cpus(data->freqdomain_cpus, buf);
}