[Xenial][PATCH 1/2] net/wireless: do not dereference invalid pointer

[Jesse Sung]

2017-08-24 16:36 GMT+08:00 Colin Ian King <colin.king at canonical.com>:
> On 24/08/17 08:30, Wen-chien Jesse Sung wrote:
>> BugLink: https://launchpad.net/bugs/1712746
>>
>> The wiphy may be NULL sometimes. Do not dereference when it's NULL.
>>
>> Signed-off-by: Wen-chien Jesse Sung <jesse.sung at canonical.com>
>> ---
>>  net/wireless/util.c | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/net/wireless/util.c b/net/wireless/util.c
>> index baf7218..e358511 100644
>> --- a/net/wireless/util.c
>> +++ b/net/wireless/util.c
>> @@ -121,7 +121,7 @@ struct ieee80211_channel *__ieee80211_get_channel(struct wiphy *wiphy,
>>       int i;
>>
>>       for (band = 0; band < IEEE80211_NUM_BANDS; band++) {
>> -             sband = wiphy->bands[band];
>> +             sband = wiphy ? wiphy->bands[band] : NULL;
>>
>>               if (!sband)
>>                       continue;
>>
>
> I am curious why wiphy can be null, is there some underlying bug
> somewhere else that is the root cause than needs fixing rather than
> papering over the issue with these workarounds?

Most likely it's a bug in mwifiex... We've already pinged Marvell and Murata.
These workarounds can be a temporary solution until there's a real fix.

>
> Colin