On 11.08.22 14:17, Greg KH wrote:
As this fixes no bug or real issue that anyone is having with 4.9, why is this needed?
This makes it easier to maintain the kernel by removing error-prone code. I mentioned this patch earlier and you seemed to be interested to at least have a look at [1]. An example where this turns out to be useful is backporting the fix for CVE-2021-39686 (see the ASB[2]). That relies on a new hook (see [3]) which is much easier to add with the simplification done in this patch. Without this patch the patch with the new hook applies cleanly but the kernel then fails due to an uninitialized hook list head. This doesn't apply to the upstream 4.x branches directly but only to the Android branches as Google seemingly backported some 5.x security features, e.g. ec74136ded792 "binder: create node flag to request sender's security context"
What devices and users would benefit from this that would need it for the next 5 months only before they move to 4.14.y? And why aren't those users on 4.14.y already?
The 4.9.y branch is also used by the Civil Infrastructure Project (CIP) to maintain a SLTS (Super Long Term Support) 4.4.y branch which is e.g. used by a community maintaining alternative Android builds for devices no longer supported by their vendors. Given that there is a community extending the lifetime of the 4.4.y LTS branch it is reasonable to assume that there are many other devices besides mine that still use the 4.4.y branch and benefit from the change to 4.9.y which will then be backported to 4.4.y by the CIP. And in extension one can assume that 4.9.y is and will be used for some devices where moving to 4.14.y is not feasible due to e.g. proprietary interfaces or simply the amount of work required to reapply all modifications from e.g. Android/Google and different vendors to a newer kernel given that maintainers of such devices are often very limited in resources and time.
Regards, Alex
[1] https://lore.kernel.org/all/YsrKlIEV2ytKcWb8@kroah.com/ [2] https://source.android.com/security/bulletin/2022-03-01#kernel-components-05 [3] https://lore.kernel.org/all/20171026084055.25482-1-mjg59@google.com/