Messages in this thread Patch in this message | | | From | Naga Chumbalkar <> | Subject | [PATCH] cpufreq: pcc-cpufreq: sanity check to prevent a NULL pointer dereference | Date | Wed, 31 Aug 2011 20:08:45 +0000 (UTC) |
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If, for whatever reason, "pr" ends up being NULL we would end up in a PANIC as seen below:
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 prevent the PANIC by failing the driver, and allowing the system to boot.
Signed-off-by: Naga Chumbalkar <nagananda.chumbalkar@hp.com> Cc: stable@kernel.org
diff --git a/drivers/cpufreq/pcc-cpufreq.c b/drivers/cpufreq/pcc-cpufreq.c index 7b0603e..cdc02ac 100644 --- 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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