From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id BB87BC433FE for ; Wed, 2 Nov 2022 02:51:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230488AbiKBCvX (ORCPT ); Tue, 1 Nov 2022 22:51:23 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40632 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230378AbiKBCvW (ORCPT ); Tue, 1 Nov 2022 22:51:22 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8EDD321E1B for ; Tue, 1 Nov 2022 19:51:21 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id DB812B82063 for ; Wed, 2 Nov 2022 02:51:19 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id B78D7C433D6; Wed, 2 Nov 2022 02:51:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1667357478; bh=GdGLe9uqOO2Oj8Z421tuQludSHEJRy8nxD4k0b7fgW0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=RYT8K+LFju9W3gFc7pJTlIN5Pb4YBjm2+FDvgKGZT6A2diX+s61lqaHw1rshdmv8g PnzB9nBlCGv8vbTvDYDYR/nwJj7KiaEYIB69jgSYJaU5+SZhsDh7a3JJCL/LoJVYsh TjZtR4oJsveP/zT/7AmCn4EVA0wSdI5pV8OOEnUA= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Yuan Yao , Dave Hansen , "Chang S. Bae" , Dave Hansen , Sasha Levin Subject: [PATCH 6.0 176/240] x86/fpu: Fix copy_xstate_to_uabi() to copy init states correctly Date: Wed, 2 Nov 2022 03:32:31 +0100 Message-Id: <20221102022115.368113314@linuxfoundation.org> X-Mailer: git-send-email 2.38.1 In-Reply-To: <20221102022111.398283374@linuxfoundation.org> References: <20221102022111.398283374@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Chang S. Bae [ Upstream commit 471f0aa7fa64e23766a1473b32d9ec3f0718895a ] When an extended state component is not present in fpstate, but in init state, the function copies from init_fpstate via copy_feature(). But, dynamic states are not present in init_fpstate because of all-zeros init states. Then retrieving them from init_fpstate will explode like this: BUG: kernel NULL pointer dereference, address: 0000000000000000 ... RIP: 0010:memcpy_erms+0x6/0x10 ? __copy_xstate_to_uabi_buf+0x381/0x870 fpu_copy_guest_fpstate_to_uabi+0x28/0x80 kvm_arch_vcpu_ioctl+0x14c/0x1460 [kvm] ? __this_cpu_preempt_check+0x13/0x20 ? vmx_vcpu_put+0x2e/0x260 [kvm_intel] kvm_vcpu_ioctl+0xea/0x6b0 [kvm] ? kvm_vcpu_ioctl+0xea/0x6b0 [kvm] ? __fget_light+0xd4/0x130 __x64_sys_ioctl+0xe3/0x910 ? debug_smp_processor_id+0x17/0x20 ? fpregs_assert_state_consistent+0x27/0x50 do_syscall_64+0x3f/0x90 entry_SYSCALL_64_after_hwframe+0x63/0xcd Adjust the 'mask' to zero out the userspace buffer for the features that are not available both from fpstate and from init_fpstate. The dynamic features depend on the compacted XSAVE format. Ensure it is enabled before reading XCOMP_BV in init_fpstate. Fixes: 2308ee57d93d ("x86/fpu/amx: Enable the AMX feature in 64-bit mode") Reported-by: Yuan Yao Suggested-by: Dave Hansen Signed-off-by: Chang S. Bae Signed-off-by: Dave Hansen Tested-by: Yuan Yao Link: https://lore.kernel.org/lkml/BYAPR11MB3717EDEF2351C958F2C86EED95259@BYAPR11MB3717.namprd11.prod.outlook.com/ Link: https://lkml.kernel.org/r/20221021185844.13472-1-chang.seok.bae@intel.com Signed-off-by: Sasha Levin --- arch/x86/kernel/fpu/xstate.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c index e77cabfa802f..59e543b95a3c 100644 --- a/arch/x86/kernel/fpu/xstate.c +++ b/arch/x86/kernel/fpu/xstate.c @@ -1125,6 +1125,15 @@ void __copy_xstate_to_uabi_buf(struct membuf to, struct fpstate *fpstate, */ mask = fpstate->user_xfeatures; + /* + * Dynamic features are not present in init_fpstate. When they are + * in an all zeros init state, remove those from 'mask' to zero + * those features in the user buffer instead of retrieving them + * from init_fpstate. + */ + if (fpu_state_size_dynamic()) + mask &= (header.xfeatures | xinit->header.xcomp_bv); + for_each_extended_xfeature(i, mask) { /* * If there was a feature or alignment gap, zero the space -- 2.35.1