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Subject[PATCH] cpufreq: powernow-k8: avoid use after free issue in cpufreq_notify_transition()
Date
From: chenqiwu <chenqiwu@xiaomi.com>

There is a potential UAF issue in cpufreq_notify_transition() that the
cpufreq of current cpu has been released before using it. So we should
make a judgement and avoid it.

Signed-off-by: chenqiwu <chenqiwu@xiaomi.com>
---
drivers/cpufreq/powernow-k8.c | 5 +++++
1 file changed, 5 insertions(+)

diff --git a/drivers/cpufreq/powernow-k8.c b/drivers/cpufreq/powernow-k8.c
index 2db2f17..7391eb0 100644
--- a/drivers/cpufreq/powernow-k8.c
+++ b/drivers/cpufreq/powernow-k8.c
@@ -913,6 +913,11 @@ static int transition_frequency_fidvid(struct powernow_k8_data *data,
freqs.new = find_khz_freq_from_fid(fid);

policy = cpufreq_cpu_get(smp_processor_id());
+ if (!policy) {
+ pr_debug("cpu %d: CPUFreq policy not found\n",
+ smp_processor_id());
+ return 1;
+ }
cpufreq_cpu_put(policy);

cpufreq_freq_transition_begin(policy, &freqs);
--
1.9.1
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