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=-9.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham 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 EA814C04AAF for ; Thu, 16 May 2019 11:40:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B3EB12166E for ; Thu, 16 May 2019 11:40:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1558006816; bh=KJF1ohD+GanVF7AGlDAg7a2PMSbc/5DsGZC2yHEZO0g=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=R2a7UFeTBOqz9rOHfNmwd8bxH1sHtajvyGTU4LHqV6OHXbqht8///905SzQRBKK0c 1ZvEK1B383hfrpPO7Ai/vMQAbaDZ+mFk9xfKNiUZD40t7WKNX2t6/Aqhszhp3ofc0J LIDkyKUDut+tG/bx/BoPI2l3FI0kIW+VRq6CkVsE= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727633AbfEPLkL (ORCPT ); Thu, 16 May 2019 07:40:11 -0400 Received: from mail.kernel.org ([198.145.29.99]:48114 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727572AbfEPLkE (ORCPT ); Thu, 16 May 2019 07:40:04 -0400 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id AD9A020862; Thu, 16 May 2019 11:40:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1558006803; bh=KJF1ohD+GanVF7AGlDAg7a2PMSbc/5DsGZC2yHEZO0g=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Uq+B5EM+bhZb70rts1oQMAu/fYkg1fUE1yHH9cjFSypxsCeS9uUNndXiwa5YbjTq6 8gLD/VIS8ikr8QRQ9R+vCBPQMRzskQocqKDrkziVnzLRvoZ2S73E3o2UHXg0uP07BF qfd4RRAd/GJPCRDQjmOT7fHwa4jmevukLVjr8S8Q= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Peter Zijlstra , Roman Gushchin , Alexei Starovoitov , Daniel Borkmann , Sasha Levin , netdev@vger.kernel.org, bpf@vger.kernel.org Subject: [PATCH AUTOSEL 5.0 23/34] bpf: Fix preempt_enable_no_resched() abuse Date: Thu, 16 May 2019 07:39:20 -0400 Message-Id: <20190516113932.8348-23-sashal@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190516113932.8348-1-sashal@kernel.org> References: <20190516113932.8348-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Peter Zijlstra [ Upstream commit 0edd6b64d1939e9e9168ff27947995bb7751db5d ] Unless the very next line is schedule(), or implies it, one must not use preempt_enable_no_resched(). It can cause a preemption to go missing and thereby cause arbitrary delays, breaking the PREEMPT=y invariant. Cc: Roman Gushchin Cc: Alexei Starovoitov Cc: Daniel Borkmann Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Alexei Starovoitov Signed-off-by: Sasha Levin --- include/linux/bpf.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/include/linux/bpf.h b/include/linux/bpf.h index e734f163bd0b9..1fbd7672e4b37 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -455,7 +455,7 @@ int bpf_prog_array_copy(struct bpf_prog_array __rcu *old_array, } \ _out: \ rcu_read_unlock(); \ - preempt_enable_no_resched(); \ + preempt_enable(); \ _ret; \ }) -- 2.20.1