From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="O2M92TMU" Received: from mail-il1-x12d.google.com (mail-il1-x12d.google.com [IPv6:2607:f8b0:4864:20::12d]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3EAD7CA; Mon, 4 Dec 2023 08:20:48 -0800 (PST) Received: by mail-il1-x12d.google.com with SMTP id e9e14a558f8ab-35d74cf427cso2507415ab.1; Mon, 04 Dec 2023 08:20:48 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1701706847; x=1702311647; darn=vger.kernel.org; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=Es+hCWrFXDwniwMcfM2dvcckNIuZXiwDz+UAIj8VFJA=; b=O2M92TMUGKE1DanM/GbOZZ4lxIDTPN6TZQu6oU9/HeyvYo2SySowudkMdSWI7FQtnO 9u+dlFALkgTCXYct0UxItfoETbE+1hzcjRf6wjzcj4tddpcESU3VfEmd2sWf1YnLtHyw gehBtvpQaZBgFtwrtY21YYvjj0CVU3AkpM4cG/yETUSuy+lZqGWCXTn0pwo8lNO0Uzyn KLrr4RkQnjwAo3XWvsA/nWuw59kimzYksjlGdeb7+GpK7yklXrn7b193n4PN8V/jjIng whNoNieAmyHKl5TDDfhhwtDjmT1q67hLDpBvsV61mG/3dzWFZT9GB3xBnL2X9ZN0pFZ8 9Qfg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1701706847; x=1702311647; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=Es+hCWrFXDwniwMcfM2dvcckNIuZXiwDz+UAIj8VFJA=; b=Chl+BPwUcELv318Xd2yMsmG1DN2Esl3/qxPfwpif2qEqoJDT3nkNISUPpUp4F7tWRs PvwOho1T3hOfVa/wkHPOyARtuIrAZTyOxxz9ZETRhRXsOAJnSrAWXhpTyVNPpWIKeLka JiE8fPcOE35CKk+yHrMAUoKXPJpAXNPYx/884f+zCejubrZMGmUYhv9S/SadWqyjU3iC LMkYDmrPrawdChJPgJaNBhaHXX63Xd2dqshpBptoYtwbXnBbT0tzzVkSmcYott6qwppZ u9XXQJczJVD5L73vayCygZvZz70tAUBvIStulG7iJvRykCNkcClN0bMrJu5lqZ88znrp dI5Q== X-Gm-Message-State: AOJu0YwGWrm1yRvHvZUAOailUJdikR8dIPJIamdbSO2+75NPmBACt5vI IoV1+OTuiv9dwuFQaoM5PZ34dt/zWDA= X-Google-Smtp-Source: AGHT+IEhr/y73+C8HGzgQnVsW0Y2ggL68hFdiBnBrbUv0IqcwH3zLyhK0X0PJii3PpbhwIeqJ1NM7A== X-Received: by 2002:a92:d082:0:b0:35d:59a2:6452 with SMTP id h2-20020a92d082000000b0035d59a26452mr4564300ilh.37.1701706847586; Mon, 04 Dec 2023 08:20:47 -0800 (PST) Received: from localhost.localdomain ([2601:648:8900:1ba9:692:26ff:fed8:afdd]) by smtp.gmail.com with ESMTPSA id y24-20020a637d18000000b005742092c211sm2492261pgc.64.2023.12.04.08.20.46 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 04 Dec 2023 08:20:47 -0800 (PST) Date: Mon, 4 Dec 2023 08:20:37 -0800 From: JP Kobryn To: Dominique Martinet Cc: Steven Rostedt , Christian Schoenebeck , ericvh@kernel.org, lucho@ionkov.net, mhiramat@kernel.org, mathieu.desnoyers@efficios.com, v9fs@lists.linux.dev, linux-trace-kernel@vger.kernel.org, bpf@vger.kernel.org, kernel-team@meta.com Subject: Re: [PATCH] 9p: prevent read overrun in protocol dump tracepoint Message-ID: References: <20231202030410.61047-1-inwardvessel@gmail.com> <1881630.VfuOzHrogK@silver> <20231202201409.10223677@rorschach.local.home> <20231202231524.4ce1d342@gandalf.local.home> 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-Disposition: inline In-Reply-To: On Sun, Dec 03, 2023 at 02:32:15PM +0900, Dominique Martinet wrote: > Steven Rostedt wrote on Sat, Dec 02, 2023 at 11:15:24PM -0500: > > > Also, for custom tracepoints e.g. bpftrace the program needs to know how > > > many bytes can be read safely even if it's just for dumping -- unless > > > dynamic_array is a "fat pointer" that conveys its own size? > > > (Sorry didn't take the time to check) > > > > Yes, there's also a __get_dynamic_array_len(line) that will return the > > allocated length of the line. Is that what you need? > > Yes, thanks! So the lower two bytes of the field are its position in > the entry and the higher two bytes its size; ok. > It doesn't look like bpftrace has any helper for it but that can > probably be sorted out if someone wants to dump data there. > > > Let's update the event to use a dynamic array and have printk fomrat to > use %*ph with that length. > > JP Kobryn, does that sound good to you? I'm not sure what you were > trying to do in the first place. > Do you want to send a v2 or shall I? Sounds good. I'll send out a v2. Thanks Steve for recommending the dynamic array macros. JP > > -- > Dominique Martinet | Asmadeus