linux-kernel - [PATCH 4.19 STABLE v2 0/2] KVM: VMX: Fix null pointer dereference

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Message-Id: <20200512002815.2708-1-sean.j.christopherson@intel.com>
Date:   Mon, 11 May 2020 17:28:13 -0700
From:   Sean Christopherson <sean.j.christopherson@...el.com>
To:     stable@...r.kernel.org,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Ben Hutchings <ben.hutchings@...ethink.co.uk>,
        Sasha Levin <sashal@...nel.org>
Cc:     Paolo Bonzini <pbonzini@...hat.com>, linux-kernel@...r.kernel.org,
        Tobias Urdin <tobias.urdin@...ero.com>
Subject: [PATCH 4.19 STABLE v2 0/2] KVM: VMX: Fix null pointer dereference

A simple fix for a null pointer dereference in vmx_vcpu_run() with an
ugly-but-safe prereq patch.

The even uglier ASM_CALL_CONSTRAINT is gone in v2 as I finally figured
out why vmx_return was undefined: GCC dropped the entire asm blob because
all outputs were deemed unused.

v2:
  - Document why there is no exact upstream commit for the fix, with
    --verbose. [Greg]
  - Tag the asm blob as volatile and drop the ASM_CALL_CONSTRAINT hack.

Sean Christopherson (2):
  KVM: VMX: Explicitly reference RCX as the vmx_vcpu pointer in asm
    blobs
  KVM: VMX: Mark RCX, RDX and RSI as clobbered in vmx_vcpu_run()'s asm
    blob

 arch/x86/kvm/vmx.c | 91 +++++++++++++++++++++++++---------------------
 1 file changed, 50 insertions(+), 41 deletions(-)

-- 
2.26.0