[PATCH] wireless: Compare ethernet addresses by unaligned safe way

[PATCH] wireless: Compare ethernet addresses by unaligned safe way

[Yauhen Kharuzhy]

When we try to run RTL8187 driver on AD BlackFin platform, we got
messages from kernel about unaligned memory access at
compare_ether_addr() calls.

Replacing of compare_ether_addr() by memcmp() fixes this problem.

Signed-off-by: Yauhen Kharuzhy <yauhen.kharuzhy@promwad.com>
---
 net/mac80211/ibss.c |    2 +-
 net/wireless/scan.c |    2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/net/mac80211/ibss.c b/net/mac80211/ibss.c
index 0b30277..bcbb1ae 100644
--- a/net/mac80211/ibss.c
+++ b/net/mac80211/ibss.c
@@ -395,7 +395,7 @@ struct sta_info *ieee80211_ibss_add_sta(struct ieee80211_sub_if_data *sdata,
 		return NULL;
 	}
 
-	if (compare_ether_addr(bssid, sdata->u.ibss.bssid))
+	if (memcmp(bssid, sdata->u.ibss.bssid, ETH_ALEN))
 		return NULL;
 
 #ifdef CONFIG_MAC80211_VERBOSE_DEBUG
diff --git a/net/wireless/scan.c b/net/wireless/scan.c
index e95b638..6ad9b59 100644
--- a/net/wireless/scan.c
+++ b/net/wireless/scan.c
@@ -134,7 +134,7 @@ static bool is_bss(struct cfg80211_bss *a,
 {
 	const u8 *ssidie;
 
-	if (bssid && compare_ether_addr(a->bssid, bssid))
+	if (bssid && memcmp(a->bssid, bssid, ETH_ALEN))
 		return false;
 
 	if (!ssid)
-- 
1.6.3.1

Re: [PATCH] wireless: Compare ethernet addresses by unaligned safe way

[Johannes Berg]

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On Tue, 2009-06-16 at 13:54 +0300, Yauhen Kharuzhy wrote:
> When we try to run RTL8187 driver on AD BlackFin platform, we got
> messages from kernel about unaligned memory access at
> compare_ether_addr() calls.
> 
> Replacing of compare_ether_addr() by memcmp() fixes this problem.

This shouldn't be necessary. Which operand is unaligned?

> --- a/net/mac80211/ibss.c
> +++ b/net/mac80211/ibss.c
> @@ -395,7 +395,7 @@ struct sta_info *ieee80211_ibss_add_sta(struct ieee80211_sub_if_data *sdata,
>  		return NULL;
>  	}
>  
> -	if (compare_ether_addr(bssid, sdata->u.ibss.bssid))
> +	if (memcmp(bssid, sdata->u.ibss.bssid, ETH_ALEN))
>  		return NULL;

So in this case it seems that it is possible that u.ibss.bssid is not
aligned, consider fixing by doing

--- ieee80211_i.h
+++ ieee80211_i.h
-	u8 bssid[ETH_ALEN];
+	u8 bssid[ETH_ALEN] __align(2);

or so instead.
 
> --- a/net/wireless/scan.c
> +++ b/net/wireless/scan.c
> @@ -134,7 +134,7 @@ static bool is_bss(struct cfg80211_bss *a,
>  {
>  	const u8 *ssidie;
>  
> -	if (bssid && compare_ether_addr(a->bssid, bssid))
> +	if (bssid && memcmp(a->bssid, bssid, ETH_ALEN))

Since a->bssid is after a pointer I can't see how it would be unaligned,
and bssid should be unaligned only if the call trace shows it's coming
from the above u.ibss.bssid.

johannes

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Re: [PATCH] wireless: Compare ethernet addresses by unaligned safe way

[Ivan Kuten]

Hello,

In net/wireless/scan.c : cfg80211_wext_siwscan there seems also unaligned allocations
for creq->ssids and creq->channels. Should it be something like that?

Modified: trunk/uClinux-dist-2008R1-RC8/compat-wireless-2009-06-11/net/wireless/scan.c
==============================================================================
--- trunk/uClinux-dist-2008R1-RC8/compat-wireless-2009-06-11/net/wireless/scan.c (original)
+++ trunk/uClinux-dist-2008R1-RC8/compat-wireless-2009-06-11/net/wireless/scan.c Fri Jun 26 14:00:52 2009
@@ -619,7 +619,7 @@
 		if (wiphy->bands[band])
 			n_channels += wiphy->bands[band]->n_channels;

-	creq = kzalloc(sizeof(*creq) + sizeof(struct cfg80211_ssid) +
+	creq = kzalloc(roundup(sizeof(*creq), 4) + roundup(sizeof(struct cfg80211_ssid), 4) +
 		       n_channels * sizeof(void *),
 		       GFP_ATOMIC);
 	if (!creq) {
@@ -629,8 +629,8 @@

 	creq->wiphy = wiphy;
 	creq->ifidx = dev->ifindex;
-	creq->ssids = (void *)(creq + 1);
-	creq->channels = (void *)(creq->ssids + 1);
+	creq->ssids = (void *)creq + roundup(sizeof(*creq), 4);
+	creq->channels = (void *)creq->ssids + roundup(sizeof(*creq->ssids), 4);
 	creq->n_channels = n_channels;
 	creq->n_ssids = 1;

Regards,
Ivan

> On Tue, 2009-06-16 at 13:54 +0300, Yauhen Kharuzhy wrote:
>> When we try to run RTL8187 driver on AD BlackFin platform, we got
>> messages from kernel about unaligned memory access at
>> compare_ether_addr() calls.
>>
>> Replacing of compare_ether_addr() by memcmp() fixes this problem.
> 
> This shouldn't be necessary. Which operand is unaligned?
> 
>> --- a/net/mac80211/ibss.c
>> +++ b/net/mac80211/ibss.c
>> @@ -395,7 +395,7 @@ struct sta_info *ieee80211_ibss_add_sta(struct ieee80211_sub_if_data *sdata,
>>  		return NULL;
>>  	}
>>  
>> -	if (compare_ether_addr(bssid, sdata->u.ibss.bssid))
>> +	if (memcmp(bssid, sdata->u.ibss.bssid, ETH_ALEN))
>>  		return NULL;
> 
> So in this case it seems that it is possible that u.ibss.bssid is not
> aligned, consider fixing by doing
> 
> --- ieee80211_i.h
> +++ ieee80211_i.h
> -	u8 bssid[ETH_ALEN];
> +	u8 bssid[ETH_ALEN] __align(2);
> 
> or so instead.
>  
>> --- a/net/wireless/scan.c
>> +++ b/net/wireless/scan.c
>> @@ -134,7 +134,7 @@ static bool is_bss(struct cfg80211_bss *a,
>>  {
>>  	const u8 *ssidie;
>>  
>> -	if (bssid && compare_ether_addr(a->bssid, bssid))
>> +	if (bssid && memcmp(a->bssid, bssid, ETH_ALEN))
> 
> Since a->bssid is after a pointer I can't see how it would be unaligned,
> and bssid should be unaligned only if the call trace shows it's coming
> from the above u.ibss.bssid.
> 
> johannes

Re: [PATCH] wireless: Compare ethernet addresses by unaligned safe way

[Johannes Berg]

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On Sun, 2009-06-28 at 15:18 +0300, Ivan Kuten wrote:
> Hello,
> 
> In net/wireless/scan.c : cfg80211_wext_siwscan there seems also unaligned allocations
> for creq->ssids and creq->channels. Should it be something like that?

Seems alright, but there is more than one instance of this, maybe you
can make a function to allocate a scan request properly and have it be
called from all the places it's needed.

johannes

> Modified: trunk/uClinux-dist-2008R1-RC8/compat-wireless-2009-06-11/net/wireless/scan.c
> ==============================================================================
> --- trunk/uClinux-dist-2008R1-RC8/compat-wireless-2009-06-11/net/wireless/scan.c (original)
> +++ trunk/uClinux-dist-2008R1-RC8/compat-wireless-2009-06-11/net/wireless/scan.c Fri Jun 26 14:00:52 2009
> @@ -619,7 +619,7 @@
>  		if (wiphy->bands[band])
>  			n_channels += wiphy->bands[band]->n_channels;
> 
> -	creq = kzalloc(sizeof(*creq) + sizeof(struct cfg80211_ssid) +
> +	creq = kzalloc(roundup(sizeof(*creq), 4) + roundup(sizeof(struct cfg80211_ssid), 4) +
>  		       n_channels * sizeof(void *),
>  		       GFP_ATOMIC);
>  	if (!creq) {
> @@ -629,8 +629,8 @@
> 
>  	creq->wiphy = wiphy;
>  	creq->ifidx = dev->ifindex;
> -	creq->ssids = (void *)(creq + 1);
> -	creq->channels = (void *)(creq->ssids + 1);
> +	creq->ssids = (void *)creq + roundup(sizeof(*creq), 4);
> +	creq->channels = (void *)creq->ssids + roundup(sizeof(*creq->ssids), 4);
>  	creq->n_channels = n_channels;
>  	creq->n_ssids = 1;
> 
> Regards,
> Ivan
> 
> > On Tue, 2009-06-16 at 13:54 +0300, Yauhen Kharuzhy wrote:
> >> When we try to run RTL8187 driver on AD BlackFin platform, we got
> >> messages from kernel about unaligned memory access at
> >> compare_ether_addr() calls.
> >>
> >> Replacing of compare_ether_addr() by memcmp() fixes this problem.
> > 
> > This shouldn't be necessary. Which operand is unaligned?
> > 
> >> --- a/net/mac80211/ibss.c
> >> +++ b/net/mac80211/ibss.c
> >> @@ -395,7 +395,7 @@ struct sta_info *ieee80211_ibss_add_sta(struct ieee80211_sub_if_data *sdata,
> >>  		return NULL;
> >>  	}
> >>  
> >> -	if (compare_ether_addr(bssid, sdata->u.ibss.bssid))
> >> +	if (memcmp(bssid, sdata->u.ibss.bssid, ETH_ALEN))
> >>  		return NULL;
> > 
> > So in this case it seems that it is possible that u.ibss.bssid is not
> > aligned, consider fixing by doing
> > 
> > --- ieee80211_i.h
> > +++ ieee80211_i.h
> > -	u8 bssid[ETH_ALEN];
> > +	u8 bssid[ETH_ALEN] __align(2);
> > 
> > or so instead.
> >  
> >> --- a/net/wireless/scan.c
> >> +++ b/net/wireless/scan.c
> >> @@ -134,7 +134,7 @@ static bool is_bss(struct cfg80211_bss *a,
> >>  {
> >>  	const u8 *ssidie;
> >>  
> >> -	if (bssid && compare_ether_addr(a->bssid, bssid))
> >> +	if (bssid && memcmp(a->bssid, bssid, ETH_ALEN))
> > 
> > Since a->bssid is after a pointer I can't see how it would be unaligned,
> > and bssid should be unaligned only if the call trace shows it's coming
> > from the above u.ibss.bssid.
> > 
> > johannes
> 
> 

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Re: [PATCH] wireless: Compare ethernet addresses by unaligned safe way

[Johannes Berg]

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On Sun, 2009-06-28 at 15:18 +0300, Ivan Kuten wrote:
> Hello,
> 
> In net/wireless/scan.c : cfg80211_wext_siwscan there seems also unaligned allocations
> for creq->ssids and creq->channels. Should it be something like that?
> 
> Modified: trunk/uClinux-dist-2008R1-RC8/compat-wireless-2009-06-11/net/wireless/scan.c
> ==============================================================================
> --- trunk/uClinux-dist-2008R1-RC8/compat-wireless-2009-06-11/net/wireless/scan.c (original)
> +++ trunk/uClinux-dist-2008R1-RC8/compat-wireless-2009-06-11/net/wireless/scan.c Fri Jun 26 14:00:52 2009
> @@ -619,7 +619,7 @@
>  		if (wiphy->bands[band])
>  			n_channels += wiphy->bands[band]->n_channels;
> 
> -	creq = kzalloc(sizeof(*creq) + sizeof(struct cfg80211_ssid) +
> +	creq = kzalloc(roundup(sizeof(*creq), 4) + roundup(sizeof(struct cfg80211_ssid), 4) +
>  		       n_channels * sizeof(void *),
>  		       GFP_ATOMIC);

Also, that should be sizeof(void *) instead of "4".

johannes

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Re: [PATCH] wireless: Compare ethernet addresses by unaligned safe way

[Ivan Kuten]

> On Sun, 2009-06-28 at 15:18 +0300, Ivan Kuten wrote:
>> Hello,
>>
>> In net/wireless/scan.c : cfg80211_wext_siwscan there seems also unaligned allocations
>> for creq->ssids and creq->channels. Should it be something like that?
> 
> Seems alright, but there is more than one instance of this, maybe you
> can make a function to allocate a scan request properly and have it be
> called from all the places it's needed.
> 
> johannes
> 

Hello Johannes,
Can you point to that multiple scan allocations? I see only one kzalloc
with followed possible alignment violation - it's in cfg80211_wext_siwscan in scan.c

Regards,
Ivan


>> Modified: trunk/uClinux-dist-2008R1-RC8/compat-wireless-2009-06-11/net/wireless/scan.c
>> ==============================================================================
>> --- trunk/uClinux-dist-2008R1-RC8/compat-wireless-2009-06-11/net/wireless/scan.c (original)
>> +++ trunk/uClinux-dist-2008R1-RC8/compat-wireless-2009-06-11/net/wireless/scan.c Fri Jun 26 14:00:52 2009
>> @@ -619,7 +619,7 @@
>>  		if (wiphy->bands[band])
>>  			n_channels += wiphy->bands[band]->n_channels;
>>
>> -	creq = kzalloc(sizeof(*creq) + sizeof(struct cfg80211_ssid) +
>> +	creq = kzalloc(roundup(sizeof(*creq), 4) + roundup(sizeof(struct cfg80211_ssid), 4) +
>>  		       n_channels * sizeof(void *),
>>  		       GFP_ATOMIC);
>>  	if (!creq) {
>> @@ -629,8 +629,8 @@
>>
>>  	creq->wiphy = wiphy;
>>  	creq->ifidx = dev->ifindex;
>> -	creq->ssids = (void *)(creq + 1);
>> -	creq->channels = (void *)(creq->ssids + 1);
>> +	creq->ssids = (void *)creq + roundup(sizeof(*creq), 4);
>> +	creq->channels = (void *)creq->ssids + roundup(sizeof(*creq->ssids), 4);
>>  	creq->n_channels = n_channels;
>>  	creq->n_ssids = 1;
>>
>> Regards,
>> Ivan
>>
>>> On Tue, 2009-06-16 at 13:54 +0300, Yauhen Kharuzhy wrote:
>>>> When we try to run RTL8187 driver on AD BlackFin platform, we got
>>>> messages from kernel about unaligned memory access at
>>>> compare_ether_addr() calls.
>>>>
>>>> Replacing of compare_ether_addr() by memcmp() fixes this problem.
>>> This shouldn't be necessary. Which operand is unaligned?
>>>
>>>> --- a/net/mac80211/ibss.c
>>>> +++ b/net/mac80211/ibss.c
>>>> @@ -395,7 +395,7 @@ struct sta_info *ieee80211_ibss_add_sta(struct ieee80211_sub_if_data *sdata,
>>>>  		return NULL;
>>>>  	}
>>>>  
>>>> -	if (compare_ether_addr(bssid, sdata->u.ibss.bssid))
>>>> +	if (memcmp(bssid, sdata->u.ibss.bssid, ETH_ALEN))
>>>>  		return NULL;
>>> So in this case it seems that it is possible that u.ibss.bssid is not
>>> aligned, consider fixing by doing
>>>
>>> --- ieee80211_i.h
>>> +++ ieee80211_i.h
>>> -	u8 bssid[ETH_ALEN];
>>> +	u8 bssid[ETH_ALEN] __align(2);
>>>
>>> or so instead.
>>>  
>>>> --- a/net/wireless/scan.c
>>>> +++ b/net/wireless/scan.c
>>>> @@ -134,7 +134,7 @@ static bool is_bss(struct cfg80211_bss *a,
>>>>  {
>>>>  	const u8 *ssidie;
>>>>  
>>>> -	if (bssid && compare_ether_addr(a->bssid, bssid))
>>>> +	if (bssid && memcmp(a->bssid, bssid, ETH_ALEN))
>>> Since a->bssid is after a pointer I can't see how it would be unaligned,
>>> and bssid should be unaligned only if the call trace shows it's coming
>>> from the above u.ibss.bssid.
>>>
>>> johannes
>>

Re: [PATCH] wireless: Compare ethernet addresses by unaligned safe way

[Johannes Berg]

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On Thu, 2009-07-23 at 20:56 +0300, Ivan Kuten wrote:
> > On Sun, 2009-06-28 at 15:18 +0300, Ivan Kuten wrote:
> >> Hello,
> >>
> >> In net/wireless/scan.c : cfg80211_wext_siwscan there seems also unaligned allocations
> >> for creq->ssids and creq->channels. Should it be something like that?
> > 
> > Seems alright, but there is more than one instance of this, maybe you
> > can make a function to allocate a scan request properly and have it be
> > called from all the places it's needed.
> > 
> > johannes
> > 
> 
> Hello Johannes,
> Can you point to that multiple scan allocations? I see only one kzalloc
> with followed possible alignment violation - it's in cfg80211_wext_siwscan in scan.c

I'm sure there's one in nl80211.c too

johannes

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Re: [PATCH] wireless: Compare ethernet addresses by unaligned safe way

[John W. Linville]

On Thu, Jul 23, 2009 at 07:59:31PM +0200, Johannes Berg wrote:
> On Thu, 2009-07-23 at 20:56 +0300, Ivan Kuten wrote:
> > > On Sun, 2009-06-28 at 15:18 +0300, Ivan Kuten wrote:
> > >> Hello,
> > >>
> > >> In net/wireless/scan.c : cfg80211_wext_siwscan there seems also unaligned allocations
> > >> for creq->ssids and creq->channels. Should it be something like that?
> > > 
> > > Seems alright, but there is more than one instance of this, maybe you
> > > can make a function to allocate a scan request properly and have it be
> > > called from all the places it's needed.
> > > 
> > > johannes
> > > 
> > 
> > Hello Johannes,
> > Can you point to that multiple scan allocations? I see only one kzalloc
> > with followed possible alignment violation - it's in cfg80211_wext_siwscan in scan.c
> 
> I'm sure there's one in nl80211.c too

Ivan/Yauhen,

Will you be posted an updated patch?  Time is short before the next merge window...

John
-- 
John W. Linville		Someday the world will need a hero, and you
linville@tuxdriver.com			might be all we have.  Be ready.