| Date | Wed, 28 Sep 2011 15:01:31 -0700 | From | Greg KH <> | Subject | [127/244] drivers/cpufreq/pcc-cpufreq.c: avoid NULL pointer dereference |
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3.0-stable review patch. If anyone has any objections, please let us know.
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From: Naga Chumbalkar <nagananda.chumbalkar@hp.com>
commit e71f5cc402ecb42b407ae52add7b173bf1c53daa upstream.
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> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
--- drivers/cpufreq/pcc-cpufreq.c | 3 +++ 1 file changed, 3 insertions(+)
--- a/drivers/cpufreq/pcc-cpufreq.c +++ b/drivers/cpufreq/pcc-cpufreq.c @@ -261,6 +261,9 @@ static int pcc_get_offset(int cpu) pr = per_cpu(processors, cpu); pcc_cpu_data = per_cpu_ptr(pcc_cpu_info, cpu); + if (!pr) + return -ENODEV; + status = acpi_evaluate_object(pr->handle, "PCCP", NULL, &buffer); if (ACPI_FAILURE(status)) return -ENODEV;
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