From patchwork Thu Dec 5 18:12:58 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Catalin Marinas X-Patchwork-Id: 11275303 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 4DAE4112B for ; Thu, 5 Dec 2019 18:13:11 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 2699424249 for ; Thu, 5 Dec 2019 18:13:11 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="oCmftWxa" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 2699424249 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:Message-Id:Date:Subject:To :From:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:In-Reply-To:References: List-Owner; bh=NMIc2dQZumnr/P6JxIVPhdJzJ10ciGYkcrZWyT+Op/I=; b=oCmftWxaTBDXOU 1ZK8zLIg23M6g3EFi7OyQDNYHtTuhZZvgodcGPpvCnIZHMYg7HJjHz1RpYU/ZN4BlCVon/NjTiZBl b0NQrEpr73uXa3aq+DnlJ/XknrfxUSPM4XiTWp90QllkFa/4/bdZkVrCfvhxiGfuMXGy7dFUG2FJ1 xrjmO29D96f1PZkeKx9eOYsJkHT8D4c7CF+LfX3vTSMlm6g+sQVMdVccyREcQ/Lg9ChTSF97Vmws9 WfjfW8oj8No5ku9SyovaqgILwX0Kz2Z6ltJnsQLyFcoBJI+kjZv9Ihk6SEjd29CruaGKAWNqE5qkM wW1BpsgbuiOJX3V1abkA==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1icvci-0006CS-Gv; Thu, 05 Dec 2019 18:13:08 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1icvcf-00069w-Dp for linux-arm-kernel@lists.infradead.org; Thu, 05 Dec 2019 18:13:06 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id A6F4D31B; Thu, 5 Dec 2019 10:13:02 -0800 (PST) Received: from arrakis.cambridge.arm.com (usa-sjc-imap-foss1.foss.arm.com [10.121.207.14]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 00DC53F718; Thu, 5 Dec 2019 10:13:01 -0800 (PST) From: Catalin Marinas To: linux-arm-kernel@lists.infradead.org Subject: [PATCH] arm64: Validate tagged addresses in access_ok() called from kernel threads Date: Thu, 5 Dec 2019 18:12:58 +0000 Message-Id: <20191205181258.27334-1-catalin.marinas@arm.com> X-Mailer: git-send-email 2.23.0 MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20191205_101305_508393_429F4C29 X-CRM114-Status: GOOD ( 11.90 ) X-Spam-Score: 0.0 (/) X-Spam-Report: SpamAssassin version 3.4.2 on bombadil.infradead.org summary: Content analysis details: (0.0 points) pts rule name description ---- ---------------------- -------------------------------------------------- 0.0 SPF_HELO_NONE SPF: HELO does not publish an SPF Record -0.0 SPF_PASS SPF: sender matches SPF record X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Will Deacon , Evgenii Stepanov Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org __range_ok(), invoked from access_ok(), clears the tag of the user address only if CONFIG_ARM64_TAGGED_ADDR_ABI is enabled and the thread opted in to the relaxed ABI. The latter sets the TIF_TAGGED_ADDR thread flag. In the case of asynchronous I/O (e.g. io_submit()), the access_ok() may be called from a kernel thread. Since kernel threads don't have TIF_TAGGED_ADDR set, access_ok() will fail for valid tagged user addresses. Example from the ffs_user_copy_worker() thread: use_mm(io_data->mm); ret = ffs_copy_to_iter(io_data->buf, ret, &io_data->data); unuse_mm(io_data->mm); Relax the __range_ok() check to always untag the user address if called in the context of a kernel thread. The user pointers would have already been checked via aio_setup_rw() -> import_{single_range,iovec}() at the time of the asynchronous I/O request. Fixes: 63f0c6037965 ("arm64: Introduce prctl() options to control the tagged user addresses ABI") Cc: # 5.4.x- Cc: Will Deacon Reported-by: Evgenii Stepanov Signed-off-by: Catalin Marinas Tested-by: Evgenii Stepanov --- arch/arm64/include/asm/uaccess.h | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/arch/arm64/include/asm/uaccess.h b/arch/arm64/include/asm/uaccess.h index 097d6bfac0b7..cccb03e1ab1f 100644 --- a/arch/arm64/include/asm/uaccess.h +++ b/arch/arm64/include/asm/uaccess.h @@ -62,8 +62,13 @@ static inline unsigned long __range_ok(const void __user *addr, unsigned long si { unsigned long ret, limit = current_thread_info()->addr_limit; + /* + * Asynchronous I/O running in a kernel thread does not have the + * TIF_TAGGED_ADDR flag of the process owning the mm, so always untag + * the user address before checking. + */ if (IS_ENABLED(CONFIG_ARM64_TAGGED_ADDR_ABI) && - test_thread_flag(TIF_TAGGED_ADDR)) + (current->flags & PF_KTHREAD || test_thread_flag(TIF_TAGGED_ADDR))) addr = untagged_addr(addr); __chk_user_ptr(addr);