From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793211769; b=tQHver8QRWxVLfAjjEwMhlRCWRiSEVK6oqJ1RwAu4PyKWKJw1Ph+EnsrNKeN+Rme2fMB 59uOV51J+JuXeOJ4TLPbeq/6e0zqD8RYuSD1Kcj3y9xpPAg/ALG+FflEzVw2R6VVdEaAI S85ZIBm8t/Mb2PVmtF9EOlN/28MjFVSBovlTUjF9M0S5dDO4S8+vpnPGYFUQPdgBdfTtb Ff3wT3T3X/qGs1mxKXDn0sv0xGwJij2bjGXzkZ0gm6Ra/wipidIuANRQSbN16ru1Nu1Up WSEj/Enege7CtONmNftH+qLt5h8ay2goA0XJ888SKjUozmto6O6LaoGmswhbXULQ62g== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793211769; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:User-Agent:X-stable:X-Patchwork-Hint: MIME-Version:Content-Transfer-Encoding; bh=hL2bLvFMqqRrUiUNHWlqVTlTJqqHabfIP8RXRZyKMMk=; b=1NBZL3ilGWPZBWCtMVn9AfNHdaxgO77/885F8d+n9TNArs+hNDMCzzmnSlqHcJEltslh SLDEJPO/x4D4/iG77UIFv6bN8l2U+VQ3TUuPgTcg3d2mDxRQdKjUI/K+yjRlkhS57i/q2 V8zK955LGDaNZQXq+NwUooQxHnhbEYKF6mj9hBkMNCjXcq/CExrPyS7nqIOqugnKQsaK3 oxQHYoNqmZf3ucwpSS0+0KET6Xet5TSY1p451RAx7A36RkmVIZei8Gr6lqsOyb8GOKh7q fE68lQhSuR/jXNAEtsFB3kAGTof6pe06+y2sDALLdVLUpx6F5vWvFZWs9cxRwjydxUA== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=cfoMvnKs; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 8F699606A32D; Wed, 28 Oct 2026 18:22:49 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key, unprotected) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=cfoMvnKs Received: by smtp.kernel.org (Postfix) with ESMTPSA id DF7441F01825; Wed, 28 Oct 2026 18:22:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1793211769; bh=hL2bLvFMqqRrUiUNHWlqVTlTJqqHabfIP8RXRZyKMMk=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=cfoMvnKsI3ur1cSINkywnKnfofJEec1tecQx5Jl7hgeK+ryjP3M6lAh9iGsCNtKbT wp+w0KF+ZftHzw6ia7Gf9SFn1Pe2lokifg6/2dDh9LKL+Auj/gyISlHAPq8RrQft22 8Tf2JYIMqCxDszLXSIvA7v+79ZsC0fllrWRBttnA= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, David Woodhouse , Amirmohammad Eftekhar , Sean Christopherson , Paolo Bonzini Subject: [PATCH 5.15 493/571] KVM: nVMX: Reset MMU back to the root MMU if loading L2 state fails for !VM-Entry Date: Wed, 28 Oct 2026 18:00:40 +0100 Message-ID: <20261028170019.725638399@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261028170008.009143722@linuxfoundation.org> References: <20261028170008.009143722@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore X-Mailing-List: patches@lists.linux.dev List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 5.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Amirmohammad Eftekhar commit c8f4cfe1cf93bce924e27f2abead7a4c4a487505 upstream. Reset the vCPU's MMU pointer back to the root MMU if loading L2 state fails in the "not from VM-Entry" case, i.e. when emulating RSM or handling KVM_SET_NESTED_STATE. Failure to unwind the MMU pointer results in KVM trying to run L1 with a nested MMU, and is especially problematic if the vCPU manages to free its nested state before the VM crashes. Constructing the root for a nested EPT MMU goes through vmcs12, which is dynamically allocated/freed when nVMX is enabled/disabled. And so if the nested state is freed with the MMU still pointing at the nested MMU, KVM will hit a NULL pointer deref when attempting to get L1=>L2 EPTP. BUG: kernel NULL pointer dereference, address: 0000000000000078 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page PGD 114a2d067 P4D 111743067 PUD 11141f067 PMD 0 Oops: Oops: 0000 [#1] SMP CPU: 20 UID: 1000 PID: 1272 Comm: nested_tdp_faul Not tainted 7.3.0-rc4-8c89f11d1a99b-sink-vm #1914 PREEMPTLAZY Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015 RIP: 0010:nested_ept_get_eptp+0xb/0x10 [kvm_intel] Call Trace: kvm_mmu_load+0xcd/0x870 [kvm] kvm_arch_vcpu_ioctl_run+0x18f5/0x1f80 [kvm] kvm_vcpu_ioctl+0x2c7/0x970 [kvm] __x64_sys_ioctl+0x90/0xd0 do_syscall_64+0x9c/0x4d0 entry_SYSCALL_64_after_hwframe+0x4b/0x53 RIP: 0033:0x47491b Modules linked in: kvm_intel kvm irqbypass CR2: 0000000000000078 ---[ end trace 0000000000000000 ]--- RIP: 0010:nested_ept_get_eptp+0xb/0x10 [kvm_intel] Cc: David Woodhouse Fixes: 72e9cbdb4338 ("KVM: nVMX: fix SMI injection in guest mode") Fixes: 8fcc4b5923af ("kvm: nVMX: Introduce KVM_CAP_NESTED_STATE") Cc: stable@vger.kernel.org Signed-off-by: Amirmohammad Eftekhar [sean: write changelog] Signed-off-by: Sean Christopherson Link: https://patch.msgid.link/20261001214356.3825100-2-seanjc@google.com Signed-off-by: Paolo Bonzini Signed-off-by: Greg Kroah-Hartman --- arch/x86/kvm/vmx/nested.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) --- a/arch/x86/kvm/vmx/nested.c +++ b/arch/x86/kvm/vmx/nested.c @@ -3538,8 +3538,10 @@ vmentry_fail_vmexit_guest_mode: vmentry_fail_vmexit: vmx_switch_vmcs(vcpu, &vmx->vmcs01); - if (!from_vmentry) + if (!from_vmentry) { + nested_ept_uninit_mmu_context(vcpu); return NVMX_VMENTRY_VMEXIT; + } load_vmcs12_host_state(vcpu, vmcs12); vmcs12->vm_exit_reason = exit_reason.full;