Return-path: Received: from mail-ig0-f182.google.com ([209.85.213.182]:38757 "EHLO mail-ig0-f182.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755058AbcA1KMG (ORCPT ); Thu, 28 Jan 2016 05:12:06 -0500 MIME-Version: 1.0 In-Reply-To: <1453974492.2217.2.camel@sipsolutions.net> References: <20160126111730.GA6765@localhost> <20160127154618.GA5717@localhost> <1453974492.2217.2.camel@sipsolutions.net> From: Julian Calaby Date: Thu, 28 Jan 2016 21:11:45 +1100 Message-ID: (sfid-20160128_111250_717631_1F54C65C) Subject: Re: [PATCH] net/mac80211/agg-rx.c: fix use of uninitialised values To: Johannes Berg Cc: Chris Bainbridge , "linux-kernel@vger.kernel.org" , linux-wireless , aryabinin@virtuozzo.com, Julia Lawall , kernel-janitors@vger.kernel.org, Joe Perches Content-Type: text/plain; charset=UTF-8 Sender: linux-wireless-owner@vger.kernel.org List-ID: Hi Johannes, On Thu, Jan 28, 2016 at 8:48 PM, Johannes Berg wrote: > On Thu, 2016-01-28 at 10:27 +1100, Julian Calaby wrote: >> I'd prefer to just set ->removed to false right after we set >> ->auto_seq as that should be faster, however I don't know if >> __ieee80211_start_rx_ba_session() is a fast path so I don't know if >> this is saving anything. > > It's not supposed to be called frequently, no. Then most of my commentary is moot. I guess the argument comes down to do we zero everything or initialise everything, and if speed isn't an issue, the former is better. >> On another note, this is an error that should be pretty easy to spot. >> Could any of the automated tools find cases where a struct containing >> a bool variable is kmalloc'd and returned without assigning all the >> bools? > > I think you'd quickly drown in false positives, since "return" isn't > necessarily something that means it needs to have been fully > initialized. True. Either way, I'm guessing that UBSAN will pick up a lot of similar bugs and the output of that is probably a much smaller haystack to dig through than just "every" kmalloc() call. Thanks, -- Julian Calaby Email: julian.calaby@gmail.com Profile: http://www.google.com/profiles/julian.calaby/