Public bug reported:
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
** Affects: linux (Ubuntu)
Importance: Undecided
Assignee: Skipper Bug Screeners (skipper-screen-team)
Status: New
** Tags: architecture-s39064 bugnameltc-202103 severity-high
targetmilestone-inin---
** Tags added: architecture-s39064 bugnameltc-202103 severity-high
targetmilestone-inin---
** Changed in: ubuntu
Assignee: (unassigned) => Skipper Bug Screeners (skipper-screen-team)
** Package changed: ubuntu => linux (Ubuntu)
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https://bugs.launchpad.net/bugs/2013088
Title:
[UBUNTU 18.04] kernel: fix __clear_user() inline assembly constraints
Status in linux package in Ubuntu:
New
Bug description:
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
To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/2013088/+subscriptions
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