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arm64: amu: Delay allocating cpumask for AMU FIE support

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[ Upstream commit d923782b041218ef3804b2fed87619b5b1a497f3 ]

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 <beata.michalska@arm.com>
Reviewed-by: Prasanna Kumar T S M <ptsm@linux.microsoft.com>
Reviewed-by: Sumit Gupta <sumitg@nvidia.com>
Reviewed-by: Sudeep Holla <sudeep.holla@arm.com>
Link: https://lore.kernel.org/r/20250131155842.3839098-1-beata.michalska@arm.com
Signed-off-by: Will Deacon <will@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Beata Michalska
2025-01-31 15:58:42 +00:00
committed by Greg Kroah-Hartman
parent 8aa4c89378
commit aa3b0ea474
1 changed files with 10 additions and 12 deletions
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22
arch/arm64/kernel/topology.c
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@@ -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);