linux-kernel - Re: [PATCH] net/mac80211/agg-rx.c: fix use of uninitialised values

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Date:	Thu, 28 Jan 2016 10:48:12 +0100
From:	Johannes Berg <johannes@...solutions.net>
To:	Julian Calaby <julian.calaby@...il.com>,
	Chris Bainbridge <chris.bainbridge@...il.com>
Cc:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	linux-wireless <linux-wireless@...r.kernel.org>,
	aryabinin@...tuozzo.com, Julia Lawall <Julia.Lawall@...6.fr>,
	kernel-janitors@...r.kernel.org, Joe Perches <joe@...ches.com>
Subject: Re: [PATCH] net/mac80211/agg-rx.c: fix use of uninitialised values

On Thu, 2016-01-28 at 10:27 +1100, Julian Calaby wrote:
> 
> This looks like a "big hammer" solution to this problem.

It is, in a way, but it also avoids future errors like it.

> 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.

> 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.

johannes