[PATCH 0/1][SRU][T] CVE-2018-18281 - stale TLB entries via mremap()

Tyler Hicks tyhicks at canonical.com
Thu Dec 6 22:15:37 UTC 2018


https://people.canonical.com/~ubuntu-security/cve/2018/CVE-2018-18281.html

 Since Linux kernel version 3.2, the mremap() syscall performs TLB flushes
 after dropping pagetable locks. If a syscall such as ftruncate() removes
 entries from the pagetables of a task that is in the middle of mremap(), a
 stale TLB entry can remain for a short time that permits access to a
 physical page after it has been released back to the page allocator and
 reused. This is fixed in the following kernel versions: 4.9.135, 4.14.78,
 4.18.16, 4.19.

Backported to Trusty from the linux-stable 4.4 branch. I tested this
change using the --mremap stressor of stress-ng. 

Tyler



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