Hi,
I suggest to include the commit: 594cc251fdd0 make 'user_access_begin()' do 'access_ok()' for CVE-2018-20669.
stable version to apply to: kernel-4.14.y and kernel-4.19.y.
From the discussion below, I checked the latest kernel and found that we should also apply other 4 patches. (total 5 patches) https://lkml.org/lkml/2020/5/12/943
patch list: commit ab10ae1c3bef lib: Reduce user_access_begin() boundaries in strncpy_from_user() and strnlen_user() commit 6e693b3ffecb x86: uaccess: Inhibit speculation past access_ok() in user_access_begin() commit 9cb2feb4d21d arch/openrisc: Fix issues with access_ok() commit 94bd8a05cd4d Fix 'acccess_ok()' on alpha and SH commit 594cc251fdd0 make 'user_access_begin()' do 'access_ok()'
Where only commit 6e693b3ffecb does not need backport modifications. I attach my backport patches in this email.
I merged the patches with kernel-4.19.127 and kernel-4.14.183 without conflicts. Build with arm64 defconfig and bootup on arm64 QEMU environment.
cheers, Miles