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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 57BE0C25B08 for ; Sat, 20 Aug 2022 11:18:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231132AbiHTLSd (ORCPT ); Sat, 20 Aug 2022 07:18:33 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54642 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S241192AbiHTLSc (ORCPT ); Sat, 20 Aug 2022 07:18:32 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2EB7217585; Sat, 20 Aug 2022 04:18:30 -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 BF628611B6; Sat, 20 Aug 2022 11:18:29 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id E52CAC433D6; Sat, 20 Aug 2022 11:18:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1660994309; bh=kELYW5Oc9wfTfaOtjKzFb+oTCYYXKgWBwjVIEpvSZzo=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=OKXpMSJ9vYjGxuMUK4WJCfaAgKUhsdFoXl0ESYoKwLeALqiPaBRqsnKgNy1y5tfVP POuAAe/pRp8raThz+MWKIPZRQrOyQB+ALR/sYsTCh7ob5Ljs8mWQIA8CcPVFMf5UFO qPhDg/8ih9B8aOMwhyWY6ohhs4p04ONPQAGpi4y0z9i/3tdZimjcpPS7keVMAFSpnZ 7NIeYCwSXRNaLAat5bRKCDrVVFnhFvbJxEc6MoC1+f6ERSgarAks05rB54cL/UyB6f PXtDQniCITsSOKNxr4Cxr/oMF/1P3tvLOGpKwn7OhzEUOpsUdfh8q8tWfRbV6c5XZK vZ52Htn66kgHw== Date: Sat, 20 Aug 2022 20:18:24 +0900 From: Masami Hiramatsu (Google) To: Steven Rostedt Cc: linux-kernel@vger.kernel.org, Ingo Molnar , Andrew Morton , Masami Hiramatsu , Tzvetomir Stoyanov , Tom Zanussi , stable@vger.kernel.org Subject: Re: [PATCH 2/4] tracing/eprobes: Do not hardcode $comm as a string Message-Id: <20220820201824.5637c4feff4a7674aebde60a@kernel.org> In-Reply-To: <20220820014833.035925907@goodmis.org> References: <20220820014035.531145719@goodmis.org> <20220820014833.035925907@goodmis.org> X-Mailer: Sylpheed 3.7.0 (GTK+ 2.24.32; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org On Fri, 19 Aug 2022 21:40:37 -0400 Steven Rostedt wrote: > From: "Steven Rostedt (Google)" > > The variable $comm is hard coded as a string, which is true for both > kprobes and uprobes, but for event probes (eprobes) it is a field name. In > most cases the "comm" field would be a string, but there's no guarantee of > that fact. > > Do not assume that comm is a string. Not to mention, it currently forces > comm fields to fault, as string processing for event probes is currently > broken. Indeed. There should be an event argument which names "comm". Eprobe might refer it. BTW, does eprobe use any special common fields? I originally introduced "$" variable for such special variables. Thank you, > > Cc: stable@vger.kernel.org > Fixes: 7491e2c44278 ("tracing: Add a probe that attaches to trace events") > Signed-off-by: Steven Rostedt (Google) > --- > kernel/trace/trace_probe.c | 5 +++-- > 1 file changed, 3 insertions(+), 2 deletions(-) > > diff --git a/kernel/trace/trace_probe.c b/kernel/trace/trace_probe.c > index dec657af363c..23dcd52ad45c 100644 > --- a/kernel/trace/trace_probe.c > +++ b/kernel/trace/trace_probe.c > @@ -622,9 +622,10 @@ static int traceprobe_parse_probe_arg_body(const char *argv, ssize_t *size, > > /* > * Since $comm and immediate string can not be dereferenced, > - * we can find those by strcmp. > + * we can find those by strcmp. But ignore for eprobes. > */ > - if (strcmp(arg, "$comm") == 0 || strncmp(arg, "\\\"", 2) == 0) { > + if (!(flags & TPARG_FL_TPOINT) && > + strcmp(arg, "$comm") == 0 || strncmp(arg, "\\\"", 2) == 0) { > /* The type of $comm must be "string", and not an array. */ > if (parg->count || (t && strcmp(t, "string"))) > goto out; > -- > 2.35.1 -- Masami Hiramatsu (Google)