linux-kernel - Re: [PATCH tip] KVM: nSVM: avoid freeing uninitialized pointers in svm_set_nested

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Message-ID: <2acc6da1-4160-c717-d890-b667cfd8c99f@amd.com>
Date:   Mon, 14 Sep 2020 11:03:28 -0500
From:   Tom Lendacky <thomas.lendacky@....com>
To:     Vitaly Kuznetsov <vkuznets@...hat.com>, x86@...nel.org
Cc:     kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
        Borislav Petkov <bp@...en8.de>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Sean Christopherson <sean.j.christopherson@...el.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <jroedel@...e.de>,
        Dan Carpenter <dan.carpenter@...cle.com>,
        Colin King <colin.king@...onical.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>
Subject: Re: [PATCH tip] KVM: nSVM: avoid freeing uninitialized pointers in
 svm_set_nested_state()

On 9/14/20 8:37 AM, Vitaly Kuznetsov wrote:
> The save and ctl pointers are passed uninitialized to kfree() when
> svm_set_nested_state() follows the 'goto out_set_gif' path. While
> the issue could've been fixed by initializing these on-stack varialbles
> to NULL, it seems preferable to eliminate 'out_set_gif' label completely
> as it is not actually a failure path and duplicating a single svm_set_gif()
> call doesn't look too bad.
> 
> Fixes: 6ccbd29ade0d ("KVM: SVM: nested: Don't allocate VMCB structures on stack")
> Addresses-Coverity: ("Uninitialized pointer read")
> Reported-by: Dan Carpenter <dan.carpenter@...cle.com>
> Reported-by: Joerg Roedel <jroedel@...e.de>
> Reported-by: Colin King <colin.king@...onical.com>
> Signed-off-by: Vitaly Kuznetsov <vkuznets@...hat.com>

Tested-by: Tom Lendacky <thomas.lendacky@....com>