From d923782b041218ef3804b2fed87619b5b1a497f3 Mon Sep 17 00:00:00 2001 From: Beata Michalska Date: Fri, 31 Jan 2025 15:58:42 +0000 Subject: [PATCH] arm64: amu: Delay allocating cpumask for AMU FIE support For the time being, the amu_fie_cpus cpumask is being exclusively used by the AMU-related internals of FIE support and is guaranteed to be valid on every access currently made. Still the mask is not being invalidated on one of the error handling code paths, which leaves a soft spot with theoretical risk of UAF for CPUMASK_OFFSTACK cases. To make things sound, delay allocating said cpumask (for CPUMASK_OFFSTACK) avoiding otherwise nasty sanitising case failing to register the cpufreq policy notifications. Signed-off-by: Beata Michalska Reviewed-by: Prasanna Kumar T S M Reviewed-by: Sumit Gupta Reviewed-by: Sudeep Holla Link: https://lore.kernel.org/r/20250131155842.3839098-1-beata.michalska@arm.com Signed-off-by: Will Deacon --- arch/arm64/kernel/topology.c | 22 ++++++++++------------ 1 file changed, 10 insertions(+), 12 deletions(-) diff --git a/arch/arm64/kernel/topology.c b/arch/arm64/kernel/topology.c index 1a2c72f3e7f8..cb180684d10d 100644 --- a/arch/arm64/kernel/topology.c +++ b/arch/arm64/kernel/topology.c @@ -194,12 +194,19 @@ static void amu_fie_setup(const struct cpumask *cpus) int cpu; /* We are already set since the last insmod of cpufreq driver */ - if (unlikely(cpumask_subset(cpus, amu_fie_cpus))) + if (cpumask_available(amu_fie_cpus) && + unlikely(cpumask_subset(cpus, amu_fie_cpus))) return; - for_each_cpu(cpu, cpus) { + for_each_cpu(cpu, cpus) if (!freq_counters_valid(cpu)) return; + + if (!cpumask_available(amu_fie_cpus) && + !zalloc_cpumask_var(&amu_fie_cpus, GFP_KERNEL)) { + WARN_ONCE(1, "Failed to allocate FIE cpumask for CPUs[%*pbl]\n", + cpumask_pr_args(cpus)); + return; } cpumask_or(amu_fie_cpus, amu_fie_cpus, cpus); @@ -237,17 +244,8 @@ static struct notifier_block init_amu_fie_notifier = { static int __init init_amu_fie(void) { - int ret; - - if (!zalloc_cpumask_var(&amu_fie_cpus, GFP_KERNEL)) - return -ENOMEM; - - ret = cpufreq_register_notifier(&init_amu_fie_notifier, + return cpufreq_register_notifier(&init_amu_fie_notifier, CPUFREQ_POLICY_NOTIFIER); - if (ret) - free_cpumask_var(amu_fie_cpus); - - return ret; } core_initcall(init_amu_fie);