linux-kernel - Re: [PATCH 1/7] KVM: Grab a reference to KVM for VM and vCPU stats file descriptors

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Message-ID: <202307121303.85C768B3BD@keescook>
Date:   Wed, 12 Jul 2023 13:04:48 -0700
From:   Kees Cook <keescook@...omium.org>
To:     Sean Christopherson <seanjc@...gle.com>
Cc:     Paolo Bonzini <pbonzini@...hat.com>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Zheng Zhang <zheng.zhang@...il.ucr.edu>
Subject: Re: [PATCH 1/7] KVM: Grab a reference to KVM for VM and vCPU stats
 file descriptors

On Tue, Jul 11, 2023 at 04:01:25PM -0700, Sean Christopherson wrote:
> Grab a reference to KVM prior to installing VM and vCPU stats file
> descriptors to ensure the underlying VM and vCPU objects are not freed
> until the last reference to any and all stats fds are dropped.
> 
> Note, the stats paths manually invoke fd_install() and so don't need to
> grab a reference before creating the file.
> 
> Fixes: ce55c049459c ("KVM: stats: Support binary stats retrieval for a VCPU")
> Fixes: fcfe1baeddbf ("KVM: stats: Support binary stats retrieval for a VM")
> Reported-by: Zheng Zhang <zheng.zhang@...il.ucr.edu>
> Closes: https://lore.kernel.org/all/CAC_GQSr3xzZaeZt85k_RCBd5kfiOve8qXo7a81Cq53LuVQ5r=Q@mail.gmail.com
> Cc: stable@...r.kernel.org
> Cc: Kees Cook <keescook@...omium.org>
> Signed-off-by: Sean Christopherson <seanjc@...gle.com>

Thanks for preparing this! Looks like the common get/put code pattern,
so I can review this patch, unlike the rest of the series. :)

Reviewed-by: Kees Cook <keescook@...omium.org>

-- 
Kees Cook