linux-kernel - Re: [PATCH] KVM: Protect vcpu->pid dereference via debugfs with RCU

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Message-ID: <168512525398.2749591.3621689713936978562.b4-ty@google.com>
Date:   Thu,  1 Jun 2023 18:20:56 -0700
From:   Sean Christopherson <seanjc@...gle.com>
To:     Sean Christopherson <seanjc@...gle.com>,
        Paolo Bonzini <pbonzini@...hat.com>
Cc:     kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] KVM: Protect vcpu->pid dereference via debugfs with RCU

On Sat, 11 Feb 2023 01:07:19 +0000, Sean Christopherson wrote:
> Wrap the vcpu->pid dereference in the debugfs hook vcpu_get_pid() with
> proper RCU read (un)lock.  Unlike the code in kvm_vcpu_ioctl(),
> vcpu_get_pid() is not a simple access; the pid pointer is passed to
> pid_nr() and fully dereferenced if the pointer is non-NULL.
> 
> Failure to acquire RCU could result in use-after-free of the old pid if
> a different task invokes KVM_RUN and puts the last reference to the old
> vcpu->pid between vcpu_get_pid() reading the pointer and dereferencing it
> in pid_nr().
> 
> [...]

Applied to kvm-x86 generic, thanks!

[1/1] KVM: Protect vcpu->pid dereference via debugfs with RCU
      https://github.com/kvm-x86/linux/commit/76021e96d781

--
https://github.com/kvm-x86/linux/tree/next
https://github.com/kvm-x86/linux/tree/fixes