[bug report] wifi: nl80211: support MLO in auth/assoc

[bug report] wifi: nl80211: support MLO in auth/assoc

[Dan Carpenter]

Hello Johannes Berg,

This is a semi-automatic email about new static checker warnings.

The patch d648c23024bd: "wifi: nl80211: support MLO in auth/assoc"
from May 31, 2022, leads to the following Smatch complaint:

    net/wireless/mlme.c:328 cfg80211_mlme_assoc()
    warn: variable dereferenced before check 'req->bss' (see line 324)

net/wireless/mlme.c
   323	
   324		err = rdev_assoc(rdev, dev, req);
                                            ^^^
req->bss dereferenced inside the function call

   325		if (!err) {
   326			int link_id;
   327	
   328			if (req->bss) {
                            ^^^^^^^^
Check for NULL is too late

   329				cfg80211_ref_bss(&rdev->wiphy, req->bss);
   330				cfg80211_hold_bss(bss_from_pub(req->bss));

regards,
dan carpenter

Re: [bug report] wifi: nl80211: support MLO in auth/assoc

[Johannes Berg]

On Wed, 2022-06-22 at 10:03 +0300, Dan Carpenter wrote:
> The patch d648c23024bd: "wifi: nl80211: support MLO in auth/assoc"
> from May 31, 2022, leads to the following Smatch complaint:
> 
>     net/wireless/mlme.c:328 cfg80211_mlme_assoc()
>     warn: variable dereferenced before check 'req->bss' (see line 324)
> 
> net/wireless/mlme.c
>    323	
>    324		err = rdev_assoc(rdev, dev, req);
>                                             ^^^
> req->bss dereferenced inside the function call
> 
>    325		if (!err) {
>    326			int link_id;
>    327	
>    328			if (req->bss) {
>                             ^^^^^^^^
> Check for NULL is too late
> 

I was writing why all of this is correct but now I realized that
literally in rdev_assoc() we dereference it ... that's obviously
garbage, I need to adjust the tracing for all of this.

But anyway I should move that into the tracing.

For now this is fine because you can't get here with req->bss == NULL
(which would imply req->link[i] != NULL for some value(s) of i) because
no driver advertises MLO support.

Thanks for the report!

johannes