[6.1.y] cpufreq: amd-pstate: add check for cpufreq_cpu_get's return value

Commit Message

Ren, Jianqi (Jacky) (CN) Dec. 9, 2024, 4:19 a.m. UTC

From: Anastasia Belova <[e-mail]>

[ Upstream commit 5493f9714e4cdaf0ee7cec15899a231400cb1a9f ]

cpufreq_cpu_get may return NULL. To avoid NULL-dereference check it
and return in case of error.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Signed-off-by: Anastasia Belova <[e-mail]>
Reviewed-by: Perry Yuan <[e-mail]>
Signed-off-by: Viresh Kumar <[e-mail]>
Signed-off-by: Jianqi Ren <[e-mail]>
---
 drivers/cpufreq/amd-pstate.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

Comments

Anastasia Belova Dec. 9, 2024, 10:07 a.m. UTC | #1

Hi!

If I'm not mistaken, backport should be accepted to a newer stable 
version 6.6 first.

Also I’ve already sent it [1]. However, I haven't received an answer yet.

[1] 
https://lore.kernel.org/lkml/[e-mail]/

Anastasia Belova

Patch

diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
index 90dcf26f0973..106aef210003 100644
--- a/drivers/cpufreq/amd-pstate.c
+++ b/drivers/cpufreq/amd-pstate.c
@@ -309,9 +309,14 @@  static void amd_pstate_adjust_perf(unsigned int cpu,
 	unsigned long max_perf, min_perf, des_perf,
 		      cap_perf, lowest_nonlinear_perf, max_freq;
 	struct cpufreq_policy *policy = cpufreq_cpu_get(cpu);
-	struct amd_cpudata *cpudata = policy->driver_data;
+	struct amd_cpudata *cpudata;
 	unsigned int target_freq;
 
+	if (!policy)
+		return;
+
+	cpudata = policy->driver_data;
+
 	cap_perf = READ_ONCE(cpudata->highest_perf);
 	lowest_nonlinear_perf = READ_ONCE(cpudata->lowest_nonlinear_perf);
 	max_freq = READ_ONCE(cpudata->max_freq);