netdev - Re: [PATCH] 4.9.13 brcmfmac: fix use-after-free on resume

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Date:   Mon, 6 Mar 2017 22:50:05 +0800
From:   Daniel J Blueman <daniel@...ra.org>
To:     Arend Van Spriel <arend.vanspriel@...adcom.com>
Cc:     Hante Meuleman <hante.meuleman@...adcom.com>,
        Pieter-Paul Giesberts <pieterpg@...adcom.com>,
        Netdev <netdev@...r.kernel.org>,
        David Miller <davem@...emloft.net>,
        linux-wireless <linux-wireless@...r.kernel.org>
Subject: Re: [PATCH] 4.9.13 brcmfmac: fix use-after-free on resume

On 6 March 2017 at 21:00, Arend Van Spriel <arend.vanspriel@...adcom.com> wrote:
> + linux-wireless
>
> On 6-3-2017 8:14, Daniel J Blueman wrote:
>> KASAN reported 'struct wireless_dev wdev' was read after being freed.
>> Fix by freeing after the access.
>
> I would rather like to see the KASAN report, because something is off
> here. This function is called with wdev as a parameter so how can it be
> accessed after free here? brcmf_remove_interface() does not free the
> wdev nor the brcmf_cfg80211_vif instance which contains the wdev.
>
> Regards,
> Arend
>
>> Signed-off-by: Daniel J Blueman <daniel@...ra.org>
>>
>> diff --git a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/p2p.c
>> b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/p2p.c
>> index de19c7c..aa0f470 100644
>> --- a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/p2p.c
>> +++ b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/p2p.c
>> @@ -2288,12 +2288,13 @@ int brcmf_p2p_del_vif(struct wiphy *wiphy,
>> struct wireless_dev *wdev)
>>                 else
>>                         err = 0;
>>         }
>> -       brcmf_remove_interface(vif->ifp, true);
>>
>> -       brcmf_cfg80211_arm_vif_event(cfg, NULL);
>>         if (vif->wdev.iftype != NL80211_IFTYPE_P2P_DEVICE)
>>                 p2p->bss_idx[P2PAPI_BSSCFG_CONNECTION].vif = NULL;
>>
>> +       brcmf_remove_interface(vif->ifp, true);
>> +       brcmf_cfg80211_arm_vif_event(cfg, NULL);
>> +
>>         return err;
>>  }

Sure, https://quora.org/kernel/brcmfmac/dmesg.txt

vmlinux, cfg80211.o, brcmfmac.o and config are in the same path; this
is against v4.9.13 stock.

Thanks,
  Daniel
-- 
Daniel J Blueman