Comment 0 for bug 2013088

Description: kernel: fix __clear_user() inline assembly constraints

Symptom: In case clear_user() crosses two pages and faults on the
               second page the kernel may write lowcore contents to the
               first page, instead of clearing it.

Problem: The __clear_user() inline assembly misses earlyclobber
               constraint modifiers. Depending on compiler and compiler
               options this may lead to incorrect code which copies kernel
               lowcore contents to user space instead of clearing memory,
               in case clear_user() faults.

Solution: Add missing earlyclobber constraint modifiers.
Preventive: yes

Upstream-ID: 89aba4c26fae4e459f755a18912845c348ee48f3

Affected Releases:
               18.04
               20.04
               22.04
               22.10
               23.04