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Date:   Mon, 30 Oct 2023 17:41:06 +0100
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Subject: Re: [PATCH v13 08/35] KVM: Introduce KVM_SET_USER_MEMORY_REGION2
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To:     Sean Christopherson <seanjc@google.com>,
        Marc Zyngier <maz@kernel.org>,
        Oliver Upton <oliver.upton@linux.dev>,
        Huacai Chen <chenhuacai@kernel.org>,
        Michael Ellerman <mpe@ellerman.id.au>,
        Anup Patel <anup@brainfault.org>,
        Paul Walmsley <paul.walmsley@sifive.com>,
        Palmer Dabbelt <palmer@dabbelt.com>,
        Albert Ou <aou@eecs.berkeley.edu>,
        Alexander Viro <viro@zeniv.linux.org.uk>,
        Christian Brauner <brauner@kernel.org>,
        "Matthew Wilcox (Oracle)" <willy@infradead.org>,
        Andrew Morton <akpm@linux-foundation.org>
Cc:     kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
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        David Matlack <dmatlack@google.com>,
        Yu Zhang <yu.c.zhang@linux.intel.com>,
        Isaku Yamahata <isaku.yamahata@intel.com>,
        =?UTF-8?B?TWlja2HDq2wgU2FsYcO8?= =?UTF-8?Q?n?= <mic@digikod.net>,
        Vlastimil Babka <vbabka@suse.cz>,
        Vishal Annapurve <vannapurve@google.com>,
        Ackerley Tng <ackerleytng@google.com>,
        Maciej Szmigiero <mail@maciej.szmigiero.name>,
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        Wang <wei.w.wang@intel.com>,
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        Isaku Yamahata <isaku.yamahata@gmail.com>,
        "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>
References: <20231027182217.3615211-1-seanjc@google.com>
 <20231027182217.3615211-9-seanjc@google.com>
From:   Paolo Bonzini <pbonzini@redhat.com>
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In-Reply-To: <20231027182217.3615211-9-seanjc@google.com>
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On 10/27/23 20:21, Sean Christopherson wrote:
> 
> +		if (ioctl == KVM_SET_USER_MEMORY_REGION)
> +			size = sizeof(struct kvm_userspace_memory_region);

This also needs a memset(&mem, 0, sizeof(mem)), otherwise the 
out-of-bounds access of the commit message becomes a kernel stack read.

Probably worth adding a check on valid flags here.

Paolo

> +		else
> +			size = sizeof(struct kvm_userspace_memory_region2);
> +
> +		/* Ensure the common parts of the two structs are identical. */
> +		SANITY_CHECK_MEM_REGION_FIELD(slot);
> +		SANITY_CHECK_MEM_REGION_FIELD(flags);
> +		SANITY_CHECK_MEM_REGION_FIELD(guest_phys_addr);
> +		SANITY_CHECK_MEM_REGION_FIELD(memory_size);
> +		SANITY_CHECK_MEM_REGION_FIELD(userspace_addr);
>