linux-kernel - Re: [PATCH] staging: wilc1000: use kernel define byte order macros

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Date:   Wed, 22 Mar 2017 12:24:04 +0300
From:   Dan Carpenter <dan.carpenter@...cle.com>
To:     Robert Perry Hooker <perry.hooker@...il.com>
Cc:     devel@...verdev.osuosl.org, gregkh@...uxfoundation.org,
        ganesh.krishna@...rochip.com, linux-kernel@...r.kernel.org,
        aditya.shankar@...rochip.com
Subject: Re: [PATCH] staging: wilc1000: use kernel define byte order macros

On Tue, Mar 21, 2017 at 03:40:10PM -0600, Robert Perry Hooker wrote:
> Thanks for taking a look, Dan. Sorry if I missed the mark here.
> 
> Can you tell me a bit more about the bug this would introduce?
> 
> I see that ieee80211_is_action is defined like this: static inline bool ieee80211_is_action(__le16 fc)
> 
> ...and that buff[FRAME_TYPE_ID]is a u8 (since FRAME_TYPE_ID = 0).
> 
> Is there an issue with calling cpu_to_le16 on a u8 that isn't encountered by implicitly casting a u8 to __le16? Or am I
> missing something else?
> 

Oh...  Hm.  You're right.  I just was thinking that since buff was a
little endian buffer but it's only reading a u8.  It should probably
be reading a le16...  The buff likely is just a regular ieee80211_hdr
struct.

So you're fixing a bug, but probably not in the right way.  We should
instead just say "struct ieee80211_hdr *hdr = buff;" and instead of
treating it like an array of u8.  Probably it requires testing...

regards,
dan carpenter