From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from relay.hostedemail.com (smtprelay0015.hostedemail.com [216.40.44.15]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id B021B388397; Fri, 26 Jun 2026 10:42:34 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=216.40.44.15 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782470556; cv=none; b=UipMcZxUDwmQQrG1oG/wWXmaXBb/FNYMZfRTJPRx3/j+nGSjzTLNtR+8b8XI0hVplKJ6GJYYvN+nrhHd3puSJ7UrkcnM7RDYSKKU21ajpoEei2fplbWsFk9eTWdwekqb3bX8OFMK4o+0aAeHySQ09uGa6/zu0MMDIwHub2KHu0Y= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782470556; c=relaxed/simple; bh=o4Ef5WodEoKWBYVZ8+hsbYTrDPckpmcgvOzyc7mX5n4=; h=Date:From:To:Cc:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=aPu4W+x+P0l/6Zn0IQkRCkHtfwV13ne0u+7Z3D1HfeLzR9h9slXiTVGbPhPVTVkc4Sqr5PEyzroHRmMJpmvHoP5BlyL1wGyfyPDFXjkzVGWcSacCdbKb8o3F5H1x3NVcLuBppMI62qM6pX4kLpxf3PxEQ+yD+DNZweBQC+Y53JA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=goodmis.org; spf=pass smtp.mailfrom=goodmis.org; arc=none smtp.client-ip=216.40.44.15 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=goodmis.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=goodmis.org Received: from omf06.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay04.hostedemail.com (Postfix) with ESMTP id E5B9D1A03A4; Fri, 26 Jun 2026 10:42:27 +0000 (UTC) Received: from [HIDDEN] (Authenticated sender: rostedt@goodmis.org) by omf06.hostedemail.com (Postfix) with ESMTPA id E3FE52000E; Fri, 26 Jun 2026 10:42:25 +0000 (UTC) Date: Fri, 26 Jun 2026 06:42:23 -0400 From: Steven Rostedt To: Martin Kaiser Cc: "Masami Hiramatsu (Google)" , linux-trace-kernel@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] tracing: eprobe: read the complete FILTER_PTR_STRING pointer Message-ID: <20260626064223.60ffeeaa@fedora> In-Reply-To: References: <20260615145500.2662456-1-martin@kaiser.cx> <20260616110910.e6420488b6a798d49951cde9@kernel.org> <20260618105227.c58c85e9cb19bce673d9a79b@kernel.org> <20260622125815.7416792c020bd3d81c01e51b@kernel.org> <20260626055440.76c28d25@fedora> X-Mailer: Claws Mail 4.4.0 (GTK 3.24.52; x86_64-redhat-linux-gnu) Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Stat-Signature: k17confegmngzkk7hujeb6axb54amsi6 X-Rspamd-Server: rspamout02 X-Rspamd-Queue-Id: E3FE52000E X-Session-Marker: 726F737465647440676F6F646D69732E6F7267 X-Session-ID: U2FsdGVkX19+58OVjlaZUwor3sUxVZXii9lRzH2NEaM= X-HE-Tag: 1782470545-550183 X-HE-Meta: U2FsdGVkX18a8k77nkdJ/Z+G7GsR73ttNOl0rhlIvVOyf/oyL9pH+YyCi6vZw/XB8RGymPvVp0OqZzvWSeqi6VpmV+M0zbaJoqrWkcixbjcPuib6gFxDGpLMb7Erd25kZr/FbBhmqGGYbPSfSnjKOew5cg7lTXe53K2KZlWKR/91DdfW51neDiF5CL5rZOVluhH/3QTmQr2PXq8a3GTNsZpBIdHpye74BvFcjDu015PeSViqoZ35fBwiMc8BUtDggPriKpmNwJkJy/GH7uIPcuNRDxXmTnmKr+wTYgbu4Tm82rEvCi37Fy6d+Vxg3H9b On Fri, 26 Jun 2026 12:20:36 +0200 Martin Kaiser wrote: > > That is, to have +u0() say "this is going to be dereferencing user space". > > > I'll add Martin's patch and see if it makes the above work. > > I've just tried your command with my patch. It works for me, filenames are > logged correctly. Yep, this definitely looks like a fix. We have; addr = rec + field->offset; Where addr points to the location of the field on the ring buffer, thus your change to make it: val = *(unsigned long *)addr; Reads the full "long size" of the event on the ring buffer, instead of reading just one byte. It is "val" that gets dereferenced later by the probe logic (the "+0u()"), which has all the protections we need. I'll queue this up. Thanks! -- Steve