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=1793831823; b=M07qC90Z4bK+x6rhLuGN6TPh6gjt/4H8Psa1F1646N8zoeoD+/eRevrcEx0hSh6P4yrv OiJvNhh+Mbvd8YudkC+KFdlrjY7FjaaL3JAfwr28Qf+AmOA3x/nEnBNJyiuq8P+EiQMhl MFruYSRhgDs72VcSsKJmi9KB7a3WNd+gnnE7ADrACaEu2NorQGCTRchJsqb/hSfOmku5R XGTY68PJlXO1dpLH4cGXMunVtxOCUPMYwUrnemHVY+kBH0nmNk1TZVvEw0PhwRoX9uvIC PO3qXHSP1UAqu8eQWdJm6j7Nhets8eu7492N5kWbEhJlLkJzHRasTSPiicp/geD0OBQ== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793831823; 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=5/hQFq3fYpaqb9UYsZ/cWyfcZNHxh0s4IXFVrGiVWXo=; b=GHOc9ugvO0Xd7bvfPcZSrXQmVQciH7OwJJW8JDGJCcUemBI3QQtX++Bmflt+iWatDmOp VD3ke8rWWQcBAXHTQXvyuiLZcmcCGOsl8tKm19f4MpNXvRDs27QJsOyOHbgiVgxAUjZV+ Yi2ORxstMWojwlBUHoof8NRdBMpkUA/lSzczcpWzZuUY+ijapvQd57QM1C1iop0eCRMmz NX599JXEeM23xQLlJwrFwJlOO8WD9E1eVbI1KON0wZYgtuqncfQD5UsjLYj7IHsT/mVY8 6E+fibWOMF2OLSlgatOraYMfBq3o60quDUqz6lcagBe4lif4KPlGu3Wj4M05DeQWgEg== 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="R214D/OZ"; 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 DC2A0606A852; Wed, 4 Nov 2026 22:37:02 +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=R214D/OZ Received: by smtp.kernel.org (Postfix) with ESMTPSA id 478901F000C1; Wed, 4 Nov 2026 22:37:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1793831822; bh=5/hQFq3fYpaqb9UYsZ/cWyfcZNHxh0s4IXFVrGiVWXo=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=R214D/OZIQsKMdh1GQONpRoJH3x6SPKT50Cz/V5R5/8T24qI1NT9ABvUgumYCvGEF F1A7dcWCgeNAIOROV2C4jwZbXviMH1hycWnu2jIxOu3J0EViIdqXdUrPUNK1v8L8iU GmYh5TJNY3LD54I1JWHt2TpecvGR3I358XWMF33w= 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 6.18 0933/1005] KVM: x86/xen: Enforce 4-byte alignment of vcpu_info registration Date: Wed, 4 Nov 2026 16:11:06 -0500 Message-ID: <20261104211109.265445840@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261104211043.516122098@linuxfoundation.org> References: <20261104211043.516122098@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 6.18-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 @@ -926,6 +926,10 @@ 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 { @@ -935,6 +939,10 @@ 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)); }