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

[Arend Van Spriel]

On 13-3-2017 10:33, Arend Van Spriel wrote:
> On 6-3-2017 15:50, Daniel J Blueman wrote:
>> On 6 March 2017 at 21:00, Arend Van Spriel  
>> 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 

 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
> 
> So this dmesg looks to be about a separate issue during resume, which
> you sent an email about earlier [1] which is about using wiphy struct
> after free. However, back to this I further checked the code and it
> seems the vif is indeed freed through the netdev destructor callback
> upon calling brcmf_remove_inteface(). However, I would prefer to store
> vif->wdev.iftype in a local variable and avoid changing the order of the
> calls in the code.

Forgot to mention some things about the commit message. Please drop the
the kernel version from the subject. You should create the patch against
the wireless-drivers tree and indicate the patch is for 4.11, ie.
"[PATCH for-4.11] brcmfmac: fix use-after-free of wireless_dev
instance". Also add as much useful information in the commit message as
possible like the proper KASAN report or at least mention that
brcmf_remove_interface() does an unregister_netdev() which results in
freeing the wireless_dev through netdev destructor callback.

Regards,
Arend

> Regards,
> Arend
> 
> [1] http://marc.info/?l=linux-netdev=148878437808750=2
> 
>> vmlinux, cfg80211.o, brcmfmac.o and config are in the same path; this
>> is against v4.9.13 stock.
> 

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

[Arend Van Spriel]

On 6-3-2017 15:50, Daniel J Blueman wrote:
> On 6 March 2017 at 21:00, Arend Van Spriel  
> 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 
>>>
>>> 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

So this dmesg looks to be about a separate issue during resume, which
you sent an email about earlier [1] which is about using wiphy struct
after free. However, back to this I further checked the code and it
seems the vif is indeed freed through the netdev destructor callback
upon calling brcmf_remove_inteface(). However, I would prefer to store
vif->wdev.iftype in a local variable and avoid changing the order of the
calls in the code.

Regards,
Arend

[1] http://marc.info/?l=linux-netdev=148878437808750=2

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

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

[Daniel J Blueman]

On 6 March 2017 at 21:00, Arend Van Spriel  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 
>>
>> 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

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

[Arend Van Spriel]

+ 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 
> 
> 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;
>  }
> 

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

[Daniel J Blueman]

KASAN reported 'struct wireless_dev wdev' was read after being freed.
Fix by freeing after the access.

Signed-off-by: Daniel J Blueman 

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;
 }
-- 
Daniel J Blueman