• Srinivas Pandruvada's avatar
    cpufreq: acpi_cpufreq: prevent crash on reading freqdomain_cpus · e2530367
    Srinivas Pandruvada authored
    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: default avatarSrinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
    Acked-by: default avatarViresh Kumar <viresh.kumar@linaro.org>
    Cc: 4.2+ <stable@vger.kernel.org> # 4.2+
    Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
    e2530367
acpi-cpufreq.c 24.3 KB