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=1794365669; b=iqbGgUJu9cJG5/kVlzGm2y0xU0K91sWpxNgLOmtdlcSLXjK87HkXtmtFUMnIudUs82y3 j8v0/KVb5Osv5vZrlcMDdHQ09w4I6UVZyr135kYUa7oPNeexoFMoop8L0WD9uibyWp6x4 L2Q3ffzagvr83zH3LqBnNxv/L7kXVcf9YMc78iCQSqrNVmS8tHv2OoPQGQiajE7EWLpq0 Y+Aa7voAr9XyJ52pBQARevOgK5dmAI3xInEFNuF8r++nNlYeochx7lBZLMUfOvibnRdz9 CD81N6B0puvzTBmjH7USvlsotljYN6owGp8ueWb8jix010Q+Rzl8FWmRomFvSNRF7hw== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794365669; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:MIME-Version:Content-Transfer-Encoding; bh=Z1DTqUxKGtgSlkjsnQi5QxSE4E0JKyNWCtvRQDTXwwI=; b=bvuSgZRquOkyzQM5e3Dxp9duimiFsiAm58T+u9Wf7hYTVB3nWfNh0dF3Xyn0n/nTsJCH ZH0mMRPvCJaLYcmLYvgCxTiUhuIGyPtgmdisBy0XCjcrJIaQvV3/JvlLuN4PZHBoPvZPM aPlkXqidRlXHHITCS3quTxTTO4c/KRHZBQCwzuqXVIbqSkCA/ieA0j7RCDUUPfz0t5x1f MVqmHJVYv9v4G+ElfcDkOhOuZ81U10Y9fqF0HpCu2mBdbyWRG0geXDJNIZrBLsUIAw4sh LsH68WU4ACAiW1AFnDfMVVe8B9y8qmp0+EAF4TY7q+Nj1K0yzXnClEQPZMyLyFqrrYw== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=iDJT4k2d; 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 F3871606A320 for ; Wed, 11 Nov 2026 02:54:28 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=iDJT4k2d Received: by smtp.kernel.org (Postfix) with ESMTPSA id DA84B1F0089F; Wed, 11 Nov 2026 02:54:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794365668; bh=Z1DTqUxKGtgSlkjsnQi5QxSE4E0JKyNWCtvRQDTXwwI=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=iDJT4k2dowDiPHPvv1o+v0qKaEkuf19y9K2Q5mJSR8qq6YWvQJ422qkobbcccQNtI NccFYysUJWxdxqI3F9zWSyvRw9h+tAOuCDyRuB8WtEA0hGrJaTTyovbqnHHWumlx0k bWhCIYDXQJhpIe8rRluctaRknRiJglqEHAtr8f2uSLp1SpuwU0mBhkMSQ5cslXye9L DdYGTc3BN7GekGnWLAG4fQJOkhJiZG5Z7McbDKWoP5I/UaLHRPxPixeOkNKYart6ax x0gk4QQYcX112JCXZua/y+kN2nkfVcaQyWBnRPh4moDq/6pgQWRtzYNel+wqohVJR1 j3cdyqe+0akmQ== From: Sasha Levin To: stable@vger.kernel.org Cc: David Woodhouse , sashiko-bot@kernel.org, Paul Durrant , Paolo Bonzini , Sasha Levin Subject: [PATCH 6.1.y] KVM: x86/xen: Enforce 4-byte alignment of vcpu_info registration Date: Tue, 10 Nov 2026 21:54:26 -0500 Message-ID: <20261111025313.769639-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20261107054109-failed-6.1-eacdb76c5f04@kernel.org> References: <20261107054109-failed-6.1-eacdb76c5f04@kernel.org> X-Mailing-List: stable@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: David Woodhouse [ Upstream commit eacdb76c5f04956035c5d7f7e1973028f30684a2 ] Xen's map_guest_area() enforces that vcpu_info is aligned to sizeof(xen_ulong_t). KVM has no such check, allowing a guest to register vcpu_info at an arbitrary byte alignment. Enforce unconditional 4-byte alignment regardless of the current shinfo mode. This is sufficient because subsequent commits ensure that all locked atomic operations on vcpu_info fields use at most 32-bit accesses. Return -ENXIO on failure, matching Xen's map_guest_area() behaviour for unaligned requests. Originally observed in review of an unrelated patch: https://lore.kernel.org/all/20260604193554.1BA311F00893@smtp.kernel.org/ Cc: stable@vger.kernel.org Fixes: 73e69a86347a ("KVM: x86/xen: register vcpu info") Reported-by: sashiko-bot@kernel.org Closes: https://lore.kernel.org/all/20260604193554.1BA311F00893@smtp.kernel.org Assisted-by: Kiro:claude-opus-4.6-1m Signed-off-by: David Woodhouse Reviewed-by: Paul Durrant Link: https://patch.msgid.link/20260831213632.81023-7-dwmw2@infradead.org Signed-off-by: Paolo Bonzini [ sashal: Omitted the HVA alignment check because only GPA registration is supported. ] Signed-off-by: Sasha Levin --- arch/x86/kvm/xen.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/arch/x86/kvm/xen.c b/arch/x86/kvm/xen.c index baa0c6d180962..e2900e5b0bedb 100644 --- a/arch/x86/kvm/xen.c +++ b/arch/x86/kvm/xen.c @@ -569,6 +569,10 @@ int kvm_xen_vcpu_set_attr(struct kvm_vcpu *vcpu, struct kvm_xen_vcpu_attr *data) break; } + r = -ENXIO; + if (!IS_ALIGNED(data->u.gpa, sizeof(u32))) + break; + r = kvm_gpc_activate(vcpu->kvm, &vcpu->arch.xen.vcpu_info_cache, NULL, KVM_HOST_USES_PFN, data->u.gpa, -- 2.53.0