From patchwork Tue Jun 7 16:11:12 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Masami Hiramatsu (Google)" X-Patchwork-Id: 12872126 X-Patchwork-Delegate: bpf@iogearbox.net 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 AA152C43334 for ; Tue, 7 Jun 2022 16:11:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1344918AbiFGQLa (ORCPT ); Tue, 7 Jun 2022 12:11:30 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50502 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1344889AbiFGQLZ (ORCPT ); Tue, 7 Jun 2022 12:11:25 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5E657F5070; Tue, 7 Jun 2022 09:11:18 -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 dfw.source.kernel.org (Postfix) with ESMTPS id ED366617C5; Tue, 7 Jun 2022 16:11:17 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5F0F5C385A5; Tue, 7 Jun 2022 16:11:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1654618277; bh=fMhk/18pmmnDcqEOb0reql1pDujGd2QhKD4ugwhr/VY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=dhwnhMMITGHny83aSk9t14jqUCSH9AmezMjMuVRFdJbPy93LeAgL9+b2f6UnraR1B U4o4bENjO40cbgbXiG51dStQZKs6cmjnkMHpN0FJ26Ml5meLWwaElejmeYT9OAAN5I ESsERD8FX0Wtohk2iWlLwNrdqB38Hg2Z99zNEG8hjhSTMIvZaZZJeu6Bic7OduibRR u959e5smm26vQilkM9Ae24fovWn46VY/mtAWi3goUDtRDEfeZ+9doZYgAMBSypzumr 8mSVmCbH3K+4/EkJa5OnTZKL8TuP6GGyfp+3O97St1vOxNLEzMhK9+hO49EjIu/y65 TsTfnT8UpHsug== From: "Masami Hiramatsu (Google)" To: Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko Cc: Masami Hiramatsu , Jiri Olsa , Steven Rostedt , linux-kernel@vger.kernel.org, netdev@vger.kernel.org, bpf@vger.kernel.org Subject: [PATCH bpf v2 2/2] rethook: Reject getting a rethook if RCU is not watching Date: Wed, 8 Jun 2022 01:11:12 +0900 Message-Id: <165461827269.280167.7379263615545598958.stgit@devnote2> X-Mailer: git-send-email 2.25.1 In-Reply-To: <165461825202.280167.12903689442217921817.stgit@devnote2> References: <165461825202.280167.12903689442217921817.stgit@devnote2> User-Agent: StGit/0.19 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org X-Patchwork-Delegate: bpf@iogearbox.net From: Masami Hiramatsu (Google) Since the rethook_recycle() will involve the call_rcu() for reclaiming the rethook_instance, the rethook must be set up at the RCU available context (non idle). This rethook_recycle() in the rethook trampoline handler is inevitable, thus the RCU available check must be done before setting the rethook trampoline. This adds a rcu_is_watching() check in the rethook_try_get() so that it will return NULL if it is called when !rcu_is_watching(). Fixes: 54ecbe6f1ed5 ("rethook: Add a generic return hook") Signed-off-by: Masami Hiramatsu (Google) Acked-by: Steven Rostedt (Google) --- kernel/trace/rethook.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/kernel/trace/rethook.c b/kernel/trace/rethook.c index b56833700d23..c69d82273ce7 100644 --- a/kernel/trace/rethook.c +++ b/kernel/trace/rethook.c @@ -154,6 +154,15 @@ struct rethook_node *rethook_try_get(struct rethook *rh) if (unlikely(!handler)) return NULL; + /* + * This expects the caller will set up a rethook on a function entry. + * When the function returns, the rethook will eventually be reclaimed + * or released in the rethook_recycle() with call_rcu(). + * This means the caller must be run in the RCU-availabe context. + */ + if (unlikely(!rcu_is_watching())) + return NULL; + fn = freelist_try_get(&rh->pool); if (!fn) return NULL;