* Regarding 711f8c3fb3db "Bluetooth: L2CAP: Fix accepting connection request for invalid SPSM"
@ 2022-12-06 11:27 Cengiz Can
2022-12-06 11:49 ` Greg KH
0 siblings, 1 reply; 3+ messages in thread
From: Cengiz Can @ 2022-12-06 11:27 UTC (permalink / raw)
To: Luiz Augusto von Dentz; +Cc: linux-bluetooth, netdev, linux-kernel, Greg KH
Hello Luiz Augusto,
I'm by no means a bluetooth expert so please bear with me if my
questions sound dumb or pointless.
I'm trying to backport commit 711f8c3fb3db ("Bluetooth: L2CAP: Fix
accepting connection request for invalid SPSM") to v4.15.y and older
stable kernels. (CVE-2022-42896)
According to the changes to `net/bluetooth/l2cap_core.c` there are two
functions that need patching:
* l2cap_le_connect_req
* l2cap_ecred_conn_req
Only the former exists in kernels <= v4.15.y. So I decided to skip
l2cap_ecred_conn_req for older kernels.
Do you think this would be enough to mitigate the issue?
If so, older kernels also lack definitions of L2CAP_CR_LE_BAD_PSM and
L2CAP_PSM_LE_DYN_END.
I see that L2CAP_CR_LE_BAD_PSM is basically the same as
L2CAP_CR_BAD_PSM so I used it to signify an error.
I think it should be enough for the sake of a backport.
What do you think?
Also the range boundary that is defined with L2CAP_PSM_LE_DYN_END is
non-existent in older kernels, and it's hard to decide which value to
use in this expression:
`if (!psm || __le16_to_cpu(psm) > L2CAP_PSM_LE_DYN_END) {`
I can easily define L2CAP_PSM_LE_DYN_END as 0x00FF and call it a day
but I had to ask if we are absolutely sure if that's the right value.
Because the comment block states that it's from the "credit based
connection request" ranges but l2cap_le_connect_req is not credit based.
Is it?
Thank you in advance.
Cengiz Can
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: Regarding 711f8c3fb3db "Bluetooth: L2CAP: Fix accepting connection request for invalid SPSM"
2022-12-06 11:27 Regarding 711f8c3fb3db "Bluetooth: L2CAP: Fix accepting connection request for invalid SPSM" Cengiz Can
@ 2022-12-06 11:49 ` Greg KH
2022-12-06 12:03 ` Cengiz Can
0 siblings, 1 reply; 3+ messages in thread
From: Greg KH @ 2022-12-06 11:49 UTC (permalink / raw)
To: Cengiz Can; +Cc: Luiz Augusto von Dentz, linux-bluetooth, netdev, linux-kernel
On Tue, Dec 06, 2022 at 02:27:27PM +0300, Cengiz Can wrote:
> Hello Luiz Augusto,
>
>
> I'm by no means a bluetooth expert so please bear with me if my
> questions sound dumb or pointless.
>
>
> I'm trying to backport commit 711f8c3fb3db ("Bluetooth: L2CAP: Fix
> accepting connection request for invalid SPSM") to v4.15.y and older
> stable kernels. (CVE-2022-42896)
>
>
> According to the changes to `net/bluetooth/l2cap_core.c` there are two
> functions that need patching:
>
>
> * l2cap_le_connect_req
> * l2cap_ecred_conn_req
>
>
>
> Only the former exists in kernels <= v4.15.y. So I decided to skip
>
> l2cap_ecred_conn_req for older kernels.
>
>
> Do you think this would be enough to mitigate the issue?
>
>
>
> If so, older kernels also lack definitions of L2CAP_CR_LE_BAD_PSM and
>
> L2CAP_PSM_LE_DYN_END.
>
>
> I see that L2CAP_CR_LE_BAD_PSM is basically the same as
> L2CAP_CR_BAD_PSM so I used it to signify an error.
>
>
> I think it should be enough for the sake of a backport.
>
>
> What do you think?
I've already done this backport and it is in the latest -rc1 stable
kernel releases. Is it not working for you there? Why do it again?
thanks,
greg k-h
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: Regarding 711f8c3fb3db "Bluetooth: L2CAP: Fix accepting connection request for invalid SPSM"
2022-12-06 11:49 ` Greg KH
@ 2022-12-06 12:03 ` Cengiz Can
0 siblings, 0 replies; 3+ messages in thread
From: Cengiz Can @ 2022-12-06 12:03 UTC (permalink / raw)
To: Greg KH; +Cc: Luiz Augusto von Dentz, linux-bluetooth, netdev, linux-kernel
On Tue, 2022-12-06 at 12:49 +0100, Greg KH wrote:
>
> I've already done this backport and it is in the latest -rc1 stable
> kernel releases. Is it not working for you there? Why do it again?
Sorry for the noise. I was just trying to make sure that I'm following
the right path.
I know that 4.4.y is no longer actively maintained but I was trying to
backport it to there as well.
Sorry for the noise again.
Cengiz Can
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2022-12-06 12:05 UTC | newest]
Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
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2022-12-06 11:27 Regarding 711f8c3fb3db "Bluetooth: L2CAP: Fix accepting connection request for invalid SPSM" Cengiz Can
2022-12-06 11:49 ` Greg KH
2022-12-06 12:03 ` Cengiz Can
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