[REGRESSION] Patch broke WPA auth: Re: [PATCH v2] wifi: cfg80211: Fix use after free for wext

[REGRESSION] Patch broke WPA auth: Re: [PATCH v2] wifi: cfg80211: Fix use after free for wext

[Hector Martin]

Hi,

This broke WPA auth entirely on brcmfmac (in offload mode) and probably
others, including on stable 6.2.3 and 6.3-rc1 (tested with iwd). Please
revert or fix. Notes below.

Reported-by: Ilya <me@0upti.me>
Reported-by: Janne Grunau <j@jannau.net>

#regzbot introduced: 015b8cc5e7c4d7
#regzbot monitor:
https://lore.kernel.org/linux-wireless/20230124141856.356646-1-alexander@wetzel-home.de/

On 24/01/2023 23.18, Alexander Wetzel wrote:
> Key information in wext.connect is not reset on (re)connect and can hold
> data from a previous connection.
> 
> Reset key data to avoid that drivers or mac80211 incorrectly detect a
> WEP connection request and access the freed or already reused memory.
> 
> Additionally optimize cfg80211_sme_connect() and avoid an useless
> schedule of conn_work.
> 
> Fixes: fffd0934b939 ("cfg80211: rework key operation")
> Cc: stable@vger.kernel.org
> Link: https://lore.kernel.org/r/c80f04d2-8159-a02a-9287-26e5ec838826@wetzel-home.de
> Signed-off-by: Alexander Wetzel <alexander@wetzel-home.de>
> 
> ---
> V2 changes:
> - updated comment
> - reset more key data
> 
> ---
>  net/wireless/sme.c | 31 ++++++++++++++++++++++++++-----
>  1 file changed, 26 insertions(+), 5 deletions(-)
> 
> diff --git a/net/wireless/sme.c b/net/wireless/sme.c
> index 123248b2c0be..0cc841c0c59b 100644
> --- a/net/wireless/sme.c
> +++ b/net/wireless/sme.c
[snip]
> @@ -1464,6 +1476,15 @@ int cfg80211_connect(struct cfg80211_registered_device *rdev,

This if branch only fires if the connection is WEP.

>  	} else {
>  		if (WARN_ON(connkeys))
>  			return -EINVAL;
> +
> +		/* connect can point to wdev->wext.connect which
> +		 * can hold key data from a previous connection
> +		 */
> +		connect->key = NULL;
> +		connect->key_len = 0;
> +		connect->key_idx = 0;

And these are indeed only used by WEP.

> +		connect->crypto.cipher_group = 0;
> +		connect->crypto.n_ciphers_pairwise = 0;

But here you're killing the info that is used for *other* auth modes too
if !WEP, breaking WPA and everything else.

>  	}
>  
>  	wdev->connect_keys = connkeys;

- Hector

Re: [REGRESSION] Patch broke WPA auth: Re: [PATCH v2] wifi: cfg80211: Fix use after free for wext

[Hans de Goede]

Hi Hector,

On 3/11/23 10:55, Hector Martin wrote:
> Hi,
> 
> This broke WPA auth entirely on brcmfmac (in offload mode) and probably
> others, including on stable 6.2.3 and 6.3-rc1 (tested with iwd). Please
> revert or fix. Notes below.
> 
> Reported-by: Ilya <me@0upti.me>
> Reported-by: Janne Grunau <j@jannau.net>
> 
> #regzbot introduced: 015b8cc5e7c4d7
> #regzbot monitor:
> https://lore.kernel.org/linux-wireless/20230124141856.356646-1-alexander@wetzel-home.de/

I can confirm this bug, I was seeing broken wifi on brcmfmac with 6.3-rc1
and I was about to start a git bisect for this this morning when I saw
this email.

Reverting 015b8cc5e7c4d7 fixes the broken wifi. Hector, thank you, you
just saved me from a bisect on somewhat slow hardware :)

Regards,

Hans






> 
> On 24/01/2023 23.18, Alexander Wetzel wrote:
>> Key information in wext.connect is not reset on (re)connect and can hold
>> data from a previous connection.
>>
>> Reset key data to avoid that drivers or mac80211 incorrectly detect a
>> WEP connection request and access the freed or already reused memory.
>>
>> Additionally optimize cfg80211_sme_connect() and avoid an useless
>> schedule of conn_work.
>>
>> Fixes: fffd0934b939 ("cfg80211: rework key operation")
>> Cc: stable@vger.kernel.org
>> Link: https://lore.kernel.org/r/c80f04d2-8159-a02a-9287-26e5ec838826@wetzel-home.de
>> Signed-off-by: Alexander Wetzel <alexander@wetzel-home.de>
>>
>> ---
>> V2 changes:
>> - updated comment
>> - reset more key data
>>
>> ---
>>  net/wireless/sme.c | 31 ++++++++++++++++++++++++++-----
>>  1 file changed, 26 insertions(+), 5 deletions(-)
>>
>> diff --git a/net/wireless/sme.c b/net/wireless/sme.c
>> index 123248b2c0be..0cc841c0c59b 100644
>> --- a/net/wireless/sme.c
>> +++ b/net/wireless/sme.c
> [snip]
>> @@ -1464,6 +1476,15 @@ int cfg80211_connect(struct cfg80211_registered_device *rdev,
> 
> This if branch only fires if the connection is WEP.
> 
>>  	} else {
>>  		if (WARN_ON(connkeys))
>>  			return -EINVAL;
>> +
>> +		/* connect can point to wdev->wext.connect which
>> +		 * can hold key data from a previous connection
>> +		 */
>> +		connect->key = NULL;
>> +		connect->key_len = 0;
>> +		connect->key_idx = 0;
> 
> And these are indeed only used by WEP.
> 
>> +		connect->crypto.cipher_group = 0;
>> +		connect->crypto.n_ciphers_pairwise = 0;
> 
> But here you're killing the info that is used for *other* auth modes too
> if !WEP, breaking WPA and everything else.
> 
>>  	}
>>  
>>  	wdev->connect_keys = connkeys;
> 
> - Hector
> 

Re: [REGRESSION] Patch broke WPA auth: Re: [PATCH v2] wifi: cfg80211: Fix use after free for wext

[Greg Kroah-Hartman]

On Sat, Mar 11, 2023 at 12:03:44PM +0100, Hans de Goede wrote:
> Hi Hector,
> 
> On 3/11/23 10:55, Hector Martin wrote:
> > Hi,
> > 
> > This broke WPA auth entirely on brcmfmac (in offload mode) and probably
> > others, including on stable 6.2.3 and 6.3-rc1 (tested with iwd). Please
> > revert or fix. Notes below.
> > 
> > Reported-by: Ilya <me@0upti.me>
> > Reported-by: Janne Grunau <j@jannau.net>
> > 
> > #regzbot introduced: 015b8cc5e7c4d7
> > #regzbot monitor:
> > https://lore.kernel.org/linux-wireless/20230124141856.356646-1-alexander@wetzel-home.de/
> 
> I can confirm this bug, I was seeing broken wifi on brcmfmac with 6.3-rc1
> and I was about to start a git bisect for this this morning when I saw
> this email.
> 
> Reverting 015b8cc5e7c4d7 fixes the broken wifi. Hector, thank you, you
> just saved me from a bisect on somewhat slow hardware :)

Great, can someone submit the revert patch to the networking tree so we
can get this resolved quickly?

thanks,

greg k-h

[PATCH] wifi: cfg80211: Partial revert "wifi: cfg80211: Fix use after free for wext"

[Hector Martin]

This reverts part of commit 015b8cc5e7c4 ("wifi: cfg80211: Fix use after
free for wext")

This commit broke WPA offload by unconditionally clearing the crypto
modes for non-WEP connections. Drop that part of the patch.

Fixes: 015b8cc5e7c4 ("wifi: cfg80211: Fix use after free for wext")
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/linux-wireless/ZAx0TWRBlGfv7pNl@kroah.com/T/#m11e6e0915ab8fa19ce8bc9695ab288c0fe018edf
Signed-off-by: Hector Martin <marcan@marcan.st>
---
 net/wireless/sme.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/net/wireless/sme.c b/net/wireless/sme.c
index 28ce13840a88..7bdeb8eea92d 100644
--- a/net/wireless/sme.c
+++ b/net/wireless/sme.c
@@ -1500,8 +1500,6 @@ int cfg80211_connect(struct cfg80211_registered_device *rdev,
 		connect->key = NULL;
 		connect->key_len = 0;
 		connect->key_idx = 0;
-		connect->crypto.cipher_group = 0;
-		connect->crypto.n_ciphers_pairwise = 0;
 	}

 	wdev->connect_keys = connkeys;
--
2.35.1

Re: [PATCH] wifi: cfg80211: Partial revert "wifi: cfg80211: Fix use after free for wext"

[Janne Grunau]

On 2023-03-11 23:19:14 +0900, Hector Martin wrote:
> This reverts part of commit 015b8cc5e7c4 ("wifi: cfg80211: Fix use after
> free for wext")
> 
> This commit broke WPA offload by unconditionally clearing the crypto
> modes for non-WEP connections. Drop that part of the patch.
> 
> Fixes: 015b8cc5e7c4 ("wifi: cfg80211: Fix use after free for wext")
> Cc: stable@vger.kernel.org
> Link: https://lore.kernel.org/linux-wireless/ZAx0TWRBlGfv7pNl@kroah.com/T/#m11e6e0915ab8fa19ce8bc9695ab288c0fe018edf
> Signed-off-by: Hector Martin <marcan@marcan.st>
> ---
>  net/wireless/sme.c | 2 --
>  1 file changed, 2 deletions(-)
> 
> diff --git a/net/wireless/sme.c b/net/wireless/sme.c
> index 28ce13840a88..7bdeb8eea92d 100644
> --- a/net/wireless/sme.c
> +++ b/net/wireless/sme.c
> @@ -1500,8 +1500,6 @@ int cfg80211_connect(struct cfg80211_registered_device *rdev,
>  		connect->key = NULL;
>  		connect->key_len = 0;
>  		connect->key_idx = 0;
> -		connect->crypto.cipher_group = 0;
> -		connect->crypto.n_ciphers_pairwise = 0;
>  	}
> 
>  	wdev->connect_keys = connkeys;

Tested-by: Janne Grunau <j@jannau.net>

thanks,

Janne

Re: [PATCH] wifi: cfg80211: Partial revert "wifi: cfg80211: Fix use after free for wext"

[Eric Curtin]

On Sat, 11 Mar 2023 at 14:28, Hector Martin <marcan@marcan.st> wrote:
>
> This reverts part of commit 015b8cc5e7c4 ("wifi: cfg80211: Fix use after
> free for wext")
>
> This commit broke WPA offload by unconditionally clearing the crypto
> modes for non-WEP connections. Drop that part of the patch.
>
> Fixes: 015b8cc5e7c4 ("wifi: cfg80211: Fix use after free for wext")
> Cc: stable@vger.kernel.org
> Link: https://lore.kernel.org/linux-wireless/ZAx0TWRBlGfv7pNl@kroah.com/T/#m11e6e0915ab8fa19ce8bc9695ab288c0fe018edf
> Signed-off-by: Hector Martin <marcan@marcan.st>

Reviewed-by: Eric Curtin <ecurtin@redhat.com>

Is mise le meas/Regards,

Eric Curtin

> ---
>  net/wireless/sme.c | 2 --
>  1 file changed, 2 deletions(-)
>
> diff --git a/net/wireless/sme.c b/net/wireless/sme.c
> index 28ce13840a88..7bdeb8eea92d 100644
> --- a/net/wireless/sme.c
> +++ b/net/wireless/sme.c
> @@ -1500,8 +1500,6 @@ int cfg80211_connect(struct cfg80211_registered_device *rdev,
>                 connect->key = NULL;
>                 connect->key_len = 0;
>                 connect->key_idx = 0;
> -               connect->crypto.cipher_group = 0;
> -               connect->crypto.n_ciphers_pairwise = 0;
>         }
>
>         wdev->connect_keys = connkeys;
> --
> 2.35.1
>
>

Re: [REGRESSION] Patch broke WPA auth: Re: [PATCH v2] wifi: cfg80211: Fix use after free for wext

[Linux regression tracking #update (Thorsten Leemhuis)]

[TLDR: This mail in primarily relevant for Linux kernel regression
tracking. See link in footer if these mails annoy you.]

On 11.03.23 10:55, Hector Martin wrote:
> 
> This broke WPA auth entirely on brcmfmac (in offload mode) and probably
> others, including on stable 6.2.3 and 6.3-rc1 (tested with iwd). Please
> revert or fix. Notes below.
> 
> Reported-by: Ilya <me@0upti.me>
> Reported-by: Janne Grunau <j@jannau.net>
> 
> #regzbot introduced: 015b8cc5e7c4d7
> #regzbot monitor:
> https://lore.kernel.org/linux-wireless/20230124141856.356646-1-alexander@wetzel-home.de/

#regzbot fix: 79d1ed5ca7db67d48
#regzbot ignore-activity

Ciao, Thorsten (wearing his 'the Linux kernel's regression tracker' hat)
--
Everything you wanna know about Linux kernel regression tracking:
https://linux-regtracking.leemhuis.info/about/#tldr
That page also explains what to do if mails like this annoy you.