bpf: mark a NULL kfunc argument precisegrafted

check_kfunc_arg() allows bpf_register_is_null() for nullable arguments
w/o marking the underlying scalar register precise. Hence a checkpoint
created on such a path would prune against arbitrary scalar value.

Fixes: 3bda08b63670 ("bpf: Allow NULL buffers in bpf_dynptr_slice(_rw)")
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20260904-register-is-null-precise-fixes-v1-5-0f5a360ff15d@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

1 files changed, 39 insertions, 0 deletions

diff --git a/drivers/cpufreq/cpufreq_powersave.c b/drivers/cpufreq/cpufreq_powersave.c
new file mode 100644
index 000000000..8d830d860
--- /dev/null
+++ b/drivers/cpufreq/cpufreq_powersave.c
@@ -0,0 +1,39 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * linux/drivers/cpufreq/cpufreq_powersave.c
+ *
+ * Copyright (C) 2002 - 2003 Dominik Brodowski <linux@brodo.de>
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/cpufreq.h>
+#include <linux/init.h>
+#include <linux/module.h>
+
+static void cpufreq_gov_powersave_limits(struct cpufreq_policy *policy)
+{
+	pr_debug("setting to %u kHz\n", policy->min);
+	__cpufreq_driver_target(policy, policy->min, CPUFREQ_RELATION_L);
+}
+
+static struct cpufreq_governor cpufreq_gov_powersave = {
+	.name		= "powersave",
+	.limits		= cpufreq_gov_powersave_limits,
+	.owner		= THIS_MODULE,
+	.flags		= CPUFREQ_GOV_STRICT_TARGET,
+};
+
+MODULE_AUTHOR("Dominik Brodowski <linux@brodo.de>");
+MODULE_DESCRIPTION("CPUfreq policy governor 'powersave'");
+MODULE_LICENSE("GPL");
+
+#ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_POWERSAVE
+struct cpufreq_governor *cpufreq_default_governor(void)
+{
+	return &cpufreq_gov_powersave;
+}
+#endif
+
+cpufreq_governor_init(cpufreq_gov_powersave);
+cpufreq_governor_exit(cpufreq_gov_powersave);