linux-kernel - Re: [PATCH v3 2/3] perf: add arm64 smmuv3 pmu driver

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <2b4a53bc-7839-6826-44ed-6099c732a31a@arm.com>
Date:   Wed, 3 Oct 2018 11:37:07 +0100
From:   Robin Murphy <robin.murphy@....com>
To:     Shameer Kolothum <shameerali.kolothum.thodi@...wei.com>,
        lorenzo.pieralisi@....com
Cc:     will.deacon@....com, mark.rutland@....com, guohanjun@...wei.com,
        john.garry@...wei.com, pabba@...eaurora.org,
        vkilari@...eaurora.org, rruigrok@...eaurora.org,
        linux-acpi@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linuxarm@...wei.com,
        neil.m.leeder@...il.com
Subject: Re: [PATCH v3 2/3] perf: add arm64 smmuv3 pmu driver

On 21/09/18 16:08, Shameer Kolothum wrote:
[...]
> +
> +	err = cpuhp_state_add_instance_nocalls(cpuhp_state_num,
> +					       &smmu_pmu->node);

In theory a hotplug event could happen as soon as the instance is 
registered...

> +	if (err) {
> +		dev_err(dev, "Error %d registering hotplug, PMU @%pa\n",
> +			err, &res_0->start);
> +		return err;
> +	}
> +
> +	/* Pick one CPU to be the preferred one to use */
> +	smmu_pmu->on_cpu = get_cpu();

...so this looks too late, i.e. a race here can result in a bogus call 
to perf_pmu_migrate_context() with an uninitialised pmu.

Robin.

> +	WARN_ON(irq_set_affinity(smmu_pmu->irq, cpumask_of(smmu_pmu->on_cpu)));
> +
> +	err = perf_pmu_register(&smmu_pmu->pmu, name, -1);
> +	if (err) {
> +		dev_err(dev, "Error %d registering PMU @%pa\n",
> +			err, &res_0->start);
> +		goto out_unregister;
> +	}
> +
> +	put_cpu();