From: Johannes Berg <johannes@sipsolutions.net>
To: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Cc: "John W. Linville" <linville@tuxdriver.com>,
linux-wireless@vger.kernel.org
Subject: Re: [Patch 1/1] wext: fix 32/64 bit alignment issue for 'point' type
Date: Thu, 30 Sep 2010 16:38:07 +0200 [thread overview]
Message-ID: <1285857487.5137.2.camel@jlt3.sipsolutions.net> (raw)
In-Reply-To: <20100930102508.GB3581@gerrit.erg.abdn.ac.uk>
On Thu, 2010-09-30 at 12:25 +0200, Gerrit Renker wrote:
> wireless: fix alignment problem
>
> With the current definition, IW_EV_POINT_PK_LEN is 12 on 64-bit and 8 on 32-bit systems,
> due to the way struct iw_event is packed (24 byte on 64-bit systems instead of 20 byte
> on 32-bit systems). Furthermore, the iwe_stream_add_point() in include/net/iw_handler.h
> also uses IW_EV_LCP_PK_LEN as header length.
>
> The current definition appears to be a typo (PK_LEN instead of LEN); it causes
> misalignment on 64 bit systems.
So, correct me if I'm wrong, the only effect this change has is changing
the second memcpy() in iwe_stream_add_point() to not copy an extra 4
bytes that will be overwritten right away by the next memcpy()
(presumably, unless the data is < 4, in which case the memcpy might
actually be out of bounds).
Where's the misalignment issue?
johannes
next prev parent reply other threads:[~2010-09-30 14:37 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-09-30 10:25 [Patch 1/1] wext: fix 32/64 bit alignment issue for 'point' type Gerrit Renker
2010-09-30 14:38 ` Johannes Berg [this message]
2010-09-30 14:40 ` Johannes Berg
2010-10-01 7:22 ` gerrit
2010-10-01 8:30 ` Johannes Berg
2010-10-11 5:14 ` Gerrit Renker
2010-10-11 9:55 ` Johannes Berg
2010-10-11 11:56 ` gerrit
2010-10-11 12:00 ` Johannes Berg
2010-10-12 5:07 ` [Patch v2 1/1] wext: fix alignment problem in serializing 'struct iw_point' Gerrit Renker
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