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drivers/cpufreq/pcc-cpufreq.c: avoid NULL pointer dereference

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per_cpu(processors, n) can be NULL, resulting in:

  Loading CPUFreq modules[  437.661360] BUG: unable to handle kernel NULL pointer dereference at (null)
  IP: [<ffffffffa0434314>] pcc_cpufreq_cpu_init+0x74/0x220 [pcc_cpufreq]

It's better to avoid the oops by failing the driver, and allowing the
system to boot.

Signed-off-by: Naga Chumbalkar <nagananda.chumbalkar@hp.com>
Cc: Dave Jones <davej@codemonkey.org.uk>
Cc: Len Brown <lenb@kernel.org>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Naga Chumbalkar 2011-09-14 16:22:23 -07:00 committed by Linus Torvalds
parent 88cee8fd77
commit e71f5cc402
1 changed files with 3 additions and 0 deletions
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3
drivers/cpufreq/pcc-cpufreq.c
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@ -261,6 +261,9 @@ static int pcc_get_offset(int cpu)
pr = per_cpu(processors, cpu); pr = per_cpu(processors, cpu);
pcc_cpu_data = per_cpu_ptr(pcc_cpu_info, cpu); pcc_cpu_data = per_cpu_ptr(pcc_cpu_info, cpu);
if (!pr)
return -ENODEV;
status = acpi_evaluate_object(pr->handle, "PCCP", NULL, &buffer); status = acpi_evaluate_object(pr->handle, "PCCP", NULL, &buffer);
if (ACPI_FAILURE(status)) if (ACPI_FAILURE(status))
return -ENODEV; return -ENODEV;