From nobody Mon Feb 9 21:03:16 2026 Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.15]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 35C813B1AA; Mon, 29 Apr 2024 10:51:54 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=192.198.163.15 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1714387915; cv=none; b=RD3n3UF1jjv/ZDZQO8y3VJJ7D+4jUlJtEGj5EoXW4SWMoNu2jtkt+lHXofI1/pGAqZBrOUHIBuenw3eeqNICrDww6HbWAUgxDrqM7zRPVejALd/SRzGL/izj+6k0xW9xKz9evsqgifPWH9mmr1mY0I6V5TGT4FNoryddvpsZnpM= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1714387915; c=relaxed/simple; bh=SPji/tPmFFHL8U+kFt+PeP/ts0wBsLsJIjNj7rxU1N4=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version:Content-Type; b=eol/wdbGdHbzhvs4d10tDxL0Ouuzzo0q8FbafMz7xQUksS+xiCKFbE8TawfnpvgIxgyJAB9BalLMow8SEuSnyFzIeZdN9peC/kJfoL1w7zVRQSYrpcPLBOW3TipXlHbfXtralr/II3kxtMo1hvQYpevYy2W6GnwJRyOaxcyfB1U= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com; spf=pass smtp.mailfrom=intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=EBcBjgMh; arc=none smtp.client-ip=192.198.163.15 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="EBcBjgMh" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1714387914; x=1745923914; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=SPji/tPmFFHL8U+kFt+PeP/ts0wBsLsJIjNj7rxU1N4=; b=EBcBjgMhea4o7vwWMNU+i63fvv/ZJiZZzdU3Ze5gWPVj+YoQYTJA8ksP JqdtwceLRyG2ACG7dGQDecn/N4+7C5rSyw7NNh2VpLpHqd88k9uG8JJ6Y ZB+jfYCLoZ8sseYWBvMdXZo7shp7kz47zUvdaqxn/rW3O23eEiRipgU4F vreyhkeZ4Yjh0gQNHwz/eeDemlKs0CkcOWCSrLIdc+Fto/zap40LsyFqz V/nypoeq/2LvJ8PSsCtw21DmZYQn7L/I68tcbJ2aAY6rsC1XAavZnGB7l CHBZFj/Ww1fntt4nK9ubgcn7bSjcl++NY6i3dWGKcEiigc7AowOO8md2O w==; X-CSE-ConnectionGUID: a7fQyHSGTvSsWkGxjdeSSA== X-CSE-MsgGUID: AyjNIbhTQq+TqGAditUk7Q== X-IronPort-AV: E=McAfee;i="6600,9927,11057"; a="10202099" X-IronPort-AV: E=Sophos;i="6.07,239,1708416000"; d="scan'208";a="10202099" Received: from orviesa007.jf.intel.com ([10.64.159.147]) by fmvoesa109.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 29 Apr 2024 03:51:52 -0700 X-CSE-ConnectionGUID: T52XsUMzQROgQuy3XeVlng== X-CSE-MsgGUID: JduiRfhfSNCMK0T8ykORiQ== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.07,239,1708416000"; d="scan'208";a="26590746" Received: from mehlow-prequal01.jf.intel.com ([10.54.102.156]) by orviesa007-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 29 Apr 2024 03:51:52 -0700 From: Dmitrii Kuvaiskii To: dave.hansen@linux.intel.com, jarkko@kernel.org, kai.huang@intel.com, haitao.huang@linux.intel.com, reinette.chatre@intel.com, linux-sgx@vger.kernel.org, linux-kernel@vger.kernel.org Cc: mona.vij@intel.com, kailun.qin@intel.com, stable@vger.kernel.org, =?UTF-8?q?Marcelina=20Ko=C5=9Bcielnicka?= Subject: [PATCH 1/2] x86/sgx: Resolve EAUG race where losing thread returns SIGBUS Date: Mon, 29 Apr 2024 03:43:29 -0700 Message-Id: <20240429104330.3636113-2-dmitrii.kuvaiskii@intel.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20240429104330.3636113-1-dmitrii.kuvaiskii@intel.com> References: <20240429104330.3636113-1-dmitrii.kuvaiskii@intel.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Organization: Intel Deutschland GmbH - Registered Address: Am Campeon 10, 85579 Neubiberg, Germany Content-Transfer-Encoding: quoted-printable Two enclave threads may try to access the same non-present enclave page simultaneously (e.g., if the SGX runtime supports lazy allocation). The threads will end up in sgx_encl_eaug_page(), racing to acquire the enclave lock. The winning thread will perform EAUG, set up the page table entry, and insert the page into encl->page_array. The losing thread will then get -EBUSY on xa_insert(&encl->page_array) and proceed to error handling path. This error handling path contains two bugs: (1) SIGBUS is sent to userspace even though the enclave page is correctly installed by another thread, and (2) sgx_encl_free_epc_page() is called that performs EREMOVE even though the enclave page was never intended to be removed. The first bug is less severe because it impacts only the user space; the second bug is more severe because it also impacts the OS state by ripping the page (added by the winning thread) from the enclave. Fix these two bugs (1) by returning VM_FAULT_NOPAGE to the generic Linux fault handler so that no signal is sent to userspace, and (2) by replacing sgx_encl_free_epc_page() with sgx_free_epc_page() so that no EREMOVE is performed. Fixes: 5a90d2c3f5ef ("x86/sgx: Support adding of pages to an initialized en= clave") Cc: stable@vger.kernel.org Reported-by: Marcelina Ko=C5=9Bcielnicka Suggested-by: Reinette Chatre Signed-off-by: Dmitrii Kuvaiskii --- arch/x86/kernel/cpu/sgx/encl.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/arch/x86/kernel/cpu/sgx/encl.c b/arch/x86/kernel/cpu/sgx/encl.c index 279148e72459..41f14b1a3025 100644 --- a/arch/x86/kernel/cpu/sgx/encl.c +++ b/arch/x86/kernel/cpu/sgx/encl.c @@ -382,8 +382,11 @@ static vm_fault_t sgx_encl_eaug_page(struct vm_area_st= ruct *vma, * If ret =3D=3D -EBUSY then page was created in another flow while * running without encl->lock */ - if (ret) + if (ret) { + if (ret =3D=3D -EBUSY) + vmret =3D VM_FAULT_NOPAGE; goto err_out_shrink; + } =20 pginfo.secs =3D (unsigned long)sgx_get_epc_virt_addr(encl->secs.epc_page); pginfo.addr =3D encl_page->desc & PAGE_MASK; @@ -419,7 +422,7 @@ static vm_fault_t sgx_encl_eaug_page(struct vm_area_str= uct *vma, err_out_shrink: sgx_encl_shrink(encl, va_page); err_out_epc: - sgx_encl_free_epc_page(epc_page); + sgx_free_epc_page(epc_page); err_out_unlock: mutex_unlock(&encl->lock); kfree(encl_page); --=20 2.34.1