From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 8858D39B4A5; Sat, 22 Aug 2026 07:28:21 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787383702; cv=none; b=E7gkQvUUz8Nof8W9MmnRSThD+ceNX1F063/Y8rrk1ZekQ8NPtXITOzFhAmNJrBAA4cgLrMMDwVqLt/0hFupnUo2Z4pzH/IT40xqjliZRpu4ipXGA5iHT3Yt/qBDuMQxvrLPEUFyoFKc5dG1cr6b4ND3XDiXyOCp3RjAuvbHbLIQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787383702; c=relaxed/simple; bh=7EH6nkAv68Ysc/kGnsAbrQ1JTNu6PdTSsRyUlPbTung=; h=Date:Message-ID:From:To:Cc:Subject:In-Reply-To:References: MIME-Version:Content-Type; b=iqTIPbI+ynrOsVsqoo2UnP9aNkygOJ4xJIldip7P6CSN0bL2TtqAyXLfInRFoOIrOyYktIJCK7wwjZ5qe/XmMHgI6UHq7bIuwmOXaOLwOt/eOC7R/i6AGnC5hZAesqklvnraKx4SQgjaEy8/AyiVhYZFQfEVHK+IIKiwP5z/Jfw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=l0tRulmt; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="l0tRulmt" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 34A3A1F000E9; Sat, 22 Aug 2026 07:28:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1787383701; bh=m7jzBL8B5ahaWiykmUYf8brzyElxeR4aRjpZhqmQmkA=; h=Date:From:To:Cc:Subject:In-Reply-To:References; b=l0tRulmt1MoVU5RU1dY7WA9U7n0oBzm3xOu69YnYEKh8HhLEGYX8ffF4BOylvRDJt Kesmpgqiq7BeOifrZ1k80ZqjPUFpyK7t90ViDT2dchCKkkjYjsdhFGvbUUJKAiTcIW DDv2KVOdM4uj2EZ3AnYzogg2lBH7e/eMbqEXA3LvytHy99ktqlBGKgKpiDcuOJcAt7 +Mv71mgjfkKXhc4LcTunzYPUm4nvcwJWo8A+1G3So0XU3UjhXzVyNZYgZu+UqDBhWP PoXxqO+VzgoP2O+hy8LkfP7XXj8GPsQnKNhBSRXuQuNyn44TmtSZF3GobqWdw79VsF 8oGEvsGDCaeyw== Received: from sofa.misterjones.org ([185.219.108.64] helo=goblin-girl.misterjones.org) by disco-boy.misterjones.org with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.98.2) (envelope-from ) id 1wxg9L-00000000DYv-0gMu; Sat, 22 Aug 2026 07:28:19 +0000 Date: Sat, 22 Aug 2026 08:28:18 +0100 Message-ID: <86zeye4nsd.wl-maz@kernel.org> From: Marc Zyngier To: "Lorenzo Stoakes (ARM)" Cc: sashiko-reviews@lists.linux.dev, kvmarm@lists.linux.dev, Oliver Upton Subject: Re: [PATCH 2/2] KVM: arm64: nv: Fix null ptr deref in kvm_nested_s2_unmap() on S2 teardown In-Reply-To: References: <20260812-kvm-arm-nested-virt-fix-v1-0-4ad883f1b6a5@kernel.org> <20260812-kvm-arm-nested-virt-fix-v1-2-4ad883f1b6a5@kernel.org> <20260812140101.D77AC1F000E9@smtp.kernel.org> User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI-EPG/1.14.7 (Harue) FLIM-LB/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL-LB/10.8 EasyPG/1.0.0 Emacs/30.1 (aarch64-unknown-linux-gnu) MULE/6.0 (HANACHIRUSATO) Precedence: bulk X-Mailing-List: kvmarm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue") Content-Type: text/plain; charset=US-ASCII X-SA-Exim-Connect-IP: 185.219.108.64 X-SA-Exim-Rcpt-To: ljs@kernel.org, sashiko-reviews@lists.linux.dev, kvmarm@lists.linux.dev, oupton@kernel.org X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false On Thu, 13 Aug 2026 16:56:02 +0100, "Lorenzo Stoakes (ARM)" wrote: > > On Wed, Aug 12, 2026 at 02:01:01PM +0000, sashiko-bot@kernel.org wrote: > > Thank you for your contribution! Sashiko AI review found 3 potential issue(s) to consider: > > > > Pre-existing issues: > > - [Critical] Use-After-Free on `kvm->arch.nested_mmus` array due to concurrent teardown. > > Addressed by Marc's changes + discussed over there. > > > - [Critical] Incomplete Fix: `kvm_nested_s2_wp()` is vulnerable to the same NULL pointer dereference and UAF. > > OK interesting! Will you respin this series with kvm_nested_s2_wp() fixed in a similar way? Something like below. Thanks, M. diff --git a/arch/arm64/kvm/nested.c b/arch/arm64/kvm/nested.c index 00580ba6e8ba0..ebc4f4dc47836 100644 --- a/arch/arm64/kvm/nested.c +++ b/arch/arm64/kvm/nested.c @@ -1262,6 +1262,14 @@ void kvm_handle_s1e2_tlbi(struct kvm_vcpu *vcpu, u32 inst, u64 val) invalidate_vncr_va(vcpu->kvm, &scope); } +static void kvm_invalidate_vncr_ipa_all(struct kvm *kvm) +{ + lockdep_assert_held_write(&kvm->mmu_lock); + + if (kvm->arch.mmu.pgt) + kvm_invalidate_vncr_ipa(kvm, 0, BIT(kvm->arch.mmu.pgt->ia_bits)); +} + void kvm_nested_s2_wp(struct kvm *kvm) { int i; @@ -1278,7 +1286,7 @@ void kvm_nested_s2_wp(struct kvm *kvm) kvm_stage2_wp_range(mmu, 0, kvm_phys_size(mmu)); } - kvm_invalidate_vncr_ipa(kvm, 0, BIT(kvm->arch.mmu.pgt->ia_bits)); + kvm_invalidate_vncr_ipa_all(kvm); } void kvm_nested_s2_unmap(struct kvm *kvm, bool may_block) @@ -1297,7 +1305,7 @@ void kvm_nested_s2_unmap(struct kvm *kvm, bool may_block) kvm_stage2_unmap_range(mmu, 0, kvm_phys_size(mmu), may_block); } - kvm_invalidate_vncr_ipa(kvm, 0, BIT(kvm->arch.mmu.pgt->ia_bits)); + kvm_invalidate_vncr_ipa_all(kvm); } void kvm_nested_s2_flush(struct kvm *kvm) -- Without deviation from the norm, progress is not possible.