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 X-Spam-Level: X-Spam-Status: No, score=-19.7 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 00685C4338F for ; Tue, 24 Aug 2021 17:02:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DF5CB615E1 for ; Tue, 24 Aug 2021 17:02:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238752AbhHXRDF (ORCPT ); Tue, 24 Aug 2021 13:03:05 -0400 Received: from mail.kernel.org ([198.145.29.99]:38844 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239155AbhHXQ75 (ORCPT ); Tue, 24 Aug 2021 12:59:57 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id A938861526; Tue, 24 Aug 2021 16:57:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1629824259; bh=t9PR/H7wvG4e7/Fr0tXfCJv5YNn3aDJuvhOk40BNd9c=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=kM7xaFPGES+3jKcgXntOtcvfjLP2tMtjTDWV/Px2ptCZvM5Zwit2WodRYx6s8wgww Tm7uBAIiwaMmXLN1iiPdy07SDmURQ+5GvuNlRcrsMQiDkXyT0FaDu6To2lDaZqJ5HL tDfY7e6I7T2ZW6vSjh0SZyk/2K0llBoIAOzef+W9HAf/HUSGAdWMgwRMMZa3jr5G5W Bfc0AILdNegVXdwG/oSAglJfXXuZWDwI7o6Pn/VAC2Q4cGm590cdnuT3R8zPTFsrIz WWemfpK00YHe9RQUP+qHcONMU9+yXQ4LBywQ2okPdnk22Rn9tOb1x0fd1A7OfsLr5j vXVc7A5vOJ5tg== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Elliot Berman , Sami Tolvanen , Kees Cook , Sasha Levin Subject: [PATCH 5.13 092/127] cfi: Use rcu_read_{un}lock_sched_notrace Date: Tue, 24 Aug 2021 12:55:32 -0400 Message-Id: <20210824165607.709387-93-sashal@kernel.org> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20210824165607.709387-1-sashal@kernel.org> References: <20210824165607.709387-1-sashal@kernel.org> MIME-Version: 1.0 X-KernelTest-Patch: http://kernel.org/pub/linux/kernel/v5.x/stable-review/patch-5.13.13-rc1.gz X-KernelTest-Tree: git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable-rc.git X-KernelTest-Branch: linux-5.13.y X-KernelTest-Patches: git://git.kernel.org/pub/scm/linux/kernel/git/stable/stable-queue.git X-KernelTest-Version: 5.13.13-rc1 X-KernelTest-Deadline: 2021-08-26T16:55+00:00 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Elliot Berman [ Upstream commit 14c4c8e41511aa8fba7fb239b20b6539b5bce201 ] If rcu_read_lock_sched tracing is enabled, the tracing subsystem can perform a jump which needs to be checked by CFI. For example, stm_ftrace source is enabled as a module and hooks into enabled ftrace events. This can cause an recursive loop where find_shadow_check_fn -> rcu_read_lock_sched -> (call to stm_ftrace generates cfi slowpath) -> find_shadow_check_fn -> rcu_read_lock_sched -> ... To avoid the recursion, either the ftrace codes needs to be marked with __no_cfi or CFI should not trace. Use the "_notrace" in CFI to avoid tracing so that CFI can guard ftrace. Signed-off-by: Elliot Berman Reviewed-by: Sami Tolvanen Cc: stable@vger.kernel.org Fixes: cf68fffb66d6 ("add support for Clang CFI") Signed-off-by: Kees Cook Link: https://lore.kernel.org/r/20210811155914.19550-1-quic_eberman@quicinc.com Signed-off-by: Sasha Levin --- kernel/cfi.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/kernel/cfi.c b/kernel/cfi.c index e17a56639766..9594cfd1cf2c 100644 --- a/kernel/cfi.c +++ b/kernel/cfi.c @@ -248,9 +248,9 @@ static inline cfi_check_fn find_shadow_check_fn(unsigned long ptr) { cfi_check_fn fn; - rcu_read_lock_sched(); + rcu_read_lock_sched_notrace(); fn = ptr_to_check_fn(rcu_dereference_sched(cfi_shadow), ptr); - rcu_read_unlock_sched(); + rcu_read_unlock_sched_notrace(); return fn; } @@ -269,11 +269,11 @@ static inline cfi_check_fn find_module_check_fn(unsigned long ptr) cfi_check_fn fn = NULL; struct module *mod; - rcu_read_lock_sched(); + rcu_read_lock_sched_notrace(); mod = __module_address(ptr); if (mod) fn = mod->cfi_check; - rcu_read_unlock_sched(); + rcu_read_unlock_sched_notrace(); return fn; } -- 2.30.2