Re: [patch] ipw2x00: shift wrap bugs setting ->rt_tsf

[Joe Perches <joe@perches.com>]

On Mon, 2014-10-27 at 12:52 +0300, Dan Carpenter wrote:
> On Fri, Oct 24, 2014 at 02:43:31AM -0700, Joe Perches wrote:
> > On Fri, 2014-10-24 at 11:15 +0300, Dan Carpenter wrote:
> > > @@ -8028,10 +8028,10 @@ static void ipw_handle_promiscuous_rx(struct ipw_priv *priv,
> > >  
> > >  	/* Zero the flags, we'll add to them as we go */
> > >  	ipw_rt->rt_flags = 0;
> > > -	ipw_rt->rt_tsf = (u64)(frame->parent_tsf[3] << 24 |
> > > -			       frame->parent_tsf[2] << 16 |
> > > -			       frame->parent_tsf[1] << 8  |
> > > -			       frame->parent_tsf[0]);
> > > +	ipw_rt->rt_tsf = (u64)frame->parent_tsf[3] << 24 |
> > > +			      frame->parent_tsf[2] << 16 |
> > > +			      frame->parent_tsf[1] << 8  |
> > > +			      frame->parent_tsf[0];
> > >  
> > >  	/* Convert to DBM */
> > >  	ipw_rt->rt_dbmsignal = signal;
> > 
> > struct ipw_rt_hdr {
> > 	struct ieee80211_radiotap_header rt_hdr;
> > 	u64 rt_tsf;      /* TSF */	/* XXX */
> > 	u8 rt_flags;	/* radiotap packet flags *
> > 	u8 rt_rate;	/* rate in 500kb/s */
> > 	__le16 rt_channel;	/* channel in mhz */
> > 	__le16 rt_chbitmask;	/* channel bitfield */
> > 	s8 rt_dbmsignal;	/* signal in dbM, kluged to signed */
> > 	s8 rt_dbmnoise;
> > 	u8 rt_antenna;	/* antenna number */
> > 	u8 payload[0];  /* payload... */
> > } __packed;
> > 
> > Maybe rt_tsf (which is otherwise unused in this code),
> > should be __le64 so maybe use (u32) ?
> > 
> > 	ipw_rt->rt_txf = cpu_to_le64((u32)(frame->parent_tsf[3] << 24 |
> > 					   frame->parent_tsf[2] << 16 |
> > 					   frame->parent_tsf[1] << 8  |
> > 					   frame->parent_tsf[0]));
> > 
> 
> Hm...  It don't think it makes sense to truncate the top bits away by
> truncating to u32.  You may be right though that there is some larger
> bugs here than just the truncation.

<shrug>  It'd be a tad faster than using multiple 64 bit
operations on a 32 bit machine.

> Both the "frame" and the "ipw_rt" struct seem to hold little endian
> values generally so probably ->rt_txf should be an __le64 like you say.
>   
> Perhaps the maintainers know what should be done?

Are there any maintainers left?

Likely this was only ever tested/used on x86 hardware.