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Date: Tue, 7 Feb 2023 12:55:54 +0000
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Subject: Re: [RFC PATCH 06/28] arm64: RME: ioctls to create and configure
 realms
To: Jean-Philippe Brucker <jean-philippe@linaro.org>,
 Steven Price <steven.price@arm.com>
Cc: kvm@vger.kernel.org, kvmarm@lists.linux.dev,
 Catalin Marinas <catalin.marinas@arm.com>, Marc Zyngier <maz@kernel.org>,
 Will Deacon <will@kernel.org>, James Morse <james.morse@arm.com>,
 Oliver Upton <oliver.upton@linux.dev>, Zenghui Yu <yuzenghui@huawei.com>,
 linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
 Joey Gouly <joey.gouly@arm.com>, Alexandru Elisei
 <alexandru.elisei@arm.com>, Christoffer Dall <christoffer.dall@arm.com>,
 Fuad Tabba <tabba@google.com>, linux-coco@lists.linux.dev
References: <20230127112248.136810-1-suzuki.poulose@arm.com>
 <20230127112932.38045-1-steven.price@arm.com>
 <20230127112932.38045-7-steven.price@arm.com> <Y+JDNkMpk9Y8ReWM@myrica>
From: Suzuki K Poulose <suzuki.poulose@arm.com>
In-Reply-To: <Y+JDNkMpk9Y8ReWM@myrica>
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On 07/02/2023 12:25, Jean-Philippe Brucker wrote:
> On Fri, Jan 27, 2023 at 11:29:10AM +0000, Steven Price wrote:
>> +static int kvm_rme_config_realm(struct kvm *kvm, struct kvm_enable_cap *cap)
>> +{
>> +	struct kvm_cap_arm_rme_config_item cfg;
>> +	struct realm *realm = &kvm->arch.realm;
>> +	int r = 0;
>> +
>> +	if (kvm_realm_state(kvm) != REALM_STATE_NONE)
>> +		return -EBUSY;
> 
> This should also check kvm_is_realm() (otherwise we dereference a NULL
> realm).

Correct, I think this should be done way up in the stack at :

kvm_vm_ioctl_enable_cap() for KVM_CAP_ARM_RME.

> 
> I was wondering about fuzzing the API to find more of this kind of issue,
> but don't know anything about it. Is there a recommended way to fuzz KVM?

Not sure either. kselftests is one possible way to drive these test at 
least for unit-testing the new ABIs. This is something we plan to add.

Thanks for catching this.

Suzuki



> Thanks,
> Jean
>