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=1794061761; b=hL7bLG0072FuieU1ukKrznZIAn5KGKCQP9XEie4SLw5M6CbjWPuLzS29ojlsq/63YNly pN5ePRD3qLUE/LElaB40YyI96Zprp32Lu5NIdcrR8SbtAjJG06OFkpMLrrn0yAWM4KTQx 92nxXF9w//KLwDJFq4rolzA+vUpW+sapL3ONRyAp0cCv+bRvh1hPy8g8NpZOB+s/JPx8V /BdhgTNrwpAQBDlUwaQ5t/ZjQgjCE+LX1D5BcM7bz/G3lhWZJVuz4KhatUp7OIeObFXWZ 2NESGHoEAw/ti4fZAXK1w3kQ9l4hkwwFxzLNkVd1axxCxdMqaxIvLFFUtlFCjKgvyAA== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794061761; 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=DHXjAZWaVb40SIbkl7vGPrsVF+1/T3e3L4xszKq1TkM=; b=YxFrmzDHi0mDfFf0irwWzwVk21Zpz15ElO/TqSRKG/fc3GmwfrKQv4YJxSCMOBCk3q2f 9pjG6isHUrMHxv7CD7V2CAlx47TGA+Rzv0jA8Ed9CYuee5hsVOCuCH6Q6qsJtvjLv1ehn HkfaqRmSCLBz5EL14ZMmq4b9amaaoBMxJnV/jUb0ANfdn9EtOmZJhuDJ0TbHDwbbkvTnv feIi1dJa9IWTUMtga7/8XIq+Jgbas6oxf2zNmLuaK0hxK/2+vOI2JzIhDNJvG0cgaqwRf 0sIOCszwbci2RE7Gdc7ZonPL8zaafJ/kWKc6UEzxSFaH2zNuhRNzSNumMH6hs4q2/jw== 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=bUImgxm2; 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 C5A8A606A326; Sat, 7 Nov 2026 14:29:20 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=bUImgxm2 Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7318B1F0089F; Sat, 7 Nov 2026 14:29:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1794061760; bh=DHXjAZWaVb40SIbkl7vGPrsVF+1/T3e3L4xszKq1TkM=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=bUImgxm2Pn5PWYbMZ3XomwCnPpO7G97SOgPV26eCnC53ycTSZWS7zTPgDFleczOzZ 1zG0d30R7s3jqSJV37vYkPw19HS10NLIMq3q7lG+kHLPpw0V3bdH4kToR0BAEp7X6e HQg6A0kX8yuBrTDdbk+KNKjar6vc3tbbkkkiXaKc= 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 6.12 0798/1536] KVM: x86/xen: Enforce 4-byte alignment of vcpu_info registration Date: Sat, 7 Nov 2026 08:46:54 -0500 Message-ID: <20261107135019.961173788@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261107134957.653319350@linuxfoundation.org> References: <20261107134957.653319350@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore 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 6.12-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 @@ -878,6 +878,10 @@ 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 { @@ -887,6 +891,10 @@ 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)); }