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=1793829131; b=Rgoea7j45JmgmCy52HsKMmFqibu0EFTBYkkoIO607B3TGPsQhl9a0GcAcCIS+bvIki3/ VzsnDRL1v3ZWFZ080zjfc2bOzITyYYXXo1SUI019OK1reF78z7sDI26GOwL3/0tGKL3SX +R4aLvbX+lTD4Qykbx6zPGDVCck12Hri6KEOvCL2mokOevQ/7pZfya5hMC2IE5lASc1YP eTOf13MnJJUjuSLULttTfreX+rjhUonuvxdc9LkYfD/5BKjSN+iwddAUZMWvucHFRo3dR I7INxELgxl2N5ZEDnzof8RZfdWMqobDoERr05a5qkSdMNdBKQ590sQsbhEHXG8NSfYw== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793829131; 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=mau3CLExpV4JMNzOIHN8AQNLsGkVGuLlVnRj7/ULmWk=; b=vhFeIXGz3vhh4vNROsF2Wv385BkAswVKA4CWpJIoA3ptjKtsqxbZVCZSw4yZYaZZDYrF 1PxZ8BZqqc55QuIEqeTTXTj3wVP7Y5yzXNV7FrKlvaZxacPPQ+XyDi8mysRlB2MOGEYtF iVb7Uk/LUTnlWBYbBk/QQK74QweQ0uypJ9rzf0x2YS0ueMaFBKNfV9DykCV8oltxH1g02 NsiT7AfKpuVk1G7Vb5pnEtlIaNgl0168DPWeHxT2ureJsPQgdUgNox9FUxfLo2LUanjau +6cRrtQHEsur+WO5UT1JZ0/F1DWU13eLSU6ufGCFX02ephGilTRDX49lE77pKsALBlg== 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=qw8qgQ2u; 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 29F66607350D; Wed, 4 Nov 2026 21:52:11 +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=qw8qgQ2u Received: by smtp.kernel.org (Postfix) with ESMTPSA id BEAC91F00919; Wed, 4 Nov 2026 21:52:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1793829131; bh=mau3CLExpV4JMNzOIHN8AQNLsGkVGuLlVnRj7/ULmWk=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=qw8qgQ2uc1xMimEF10S5AikgD5bQDkDSqU5fAlPcOCiS7yaPLy05XV4u01hS+SD7q 3C4mBHDlAcpzzRduHq8UpV16OJQc09ayw6D2OvfvSBir4ShP46bUVVGdHn8t9FNwai 7rnfPlgX9ppKjXQGwFgcUvas9ba5D/OxTnkWGVCY= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, sashiko-bot@kernel.org, David Woodhouse , Paul Durrant , Paolo Bonzini Subject: [PATCH 7.3 465/547] KVM: x86/xen: Enforce 4-byte alignment of vcpu_info registration Date: Wed, 4 Nov 2026 16:10:49 -0500 Message-ID: <20261104211051.565461144@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261104211038.406938024@linuxfoundation.org> References: <20261104211038.406938024@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 7.3-stable review patch. If anyone has any objections, please let me know. ------------------ From: David Woodhouse commit eacdb76c5f04956035c5d7f7e1973028f30684a2 upstream. 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 Signed-off-by: Greg Kroah-Hartman --- arch/x86/kvm/xen.c | 8 ++++++++ 1 file changed, 8 insertions(+) --- a/arch/x86/kvm/xen.c +++ b/arch/x86/kvm/xen.c @@ -941,6 +941,10 @@ int kvm_xen_vcpu_set_attr(struct kvm_vcp break; } + r = -ENXIO; + if (!IS_ALIGNED(data->u.gpa, sizeof(u32))) + break; + r = kvm_gpc_activate(&vcpu->arch.xen.vcpu_info_cache, data->u.gpa, sizeof(struct vcpu_info)); } else { @@ -950,6 +954,10 @@ int kvm_xen_vcpu_set_attr(struct kvm_vcp break; } + r = -ENXIO; + if (!IS_ALIGNED(data->u.hva, sizeof(u32))) + break; + r = kvm_gpc_activate_hva(&vcpu->arch.xen.vcpu_info_cache, data->u.hva, sizeof(struct vcpu_info)); }