Description: ANDROID: binder: synchronize_rcu() when using POLLFREE
References:
 https://source.android.com/security/bulletin/2020-02-01.html
Notes:
 bwh> Although the upstream commit has been backported to 4.9, it
 bwh> depends on commit 7a4408c6bd3e "binder: make sure accesses to
 bwh> proc/thread are safe" which has not.
 carnil> For tracking, this was in 4.9.196 with
 carnil> b6c6212514fe9f2387fc6677181028d4a9ae20c7 commit in linux-4.9.y
 carnil> branch
Bugs:
upstream: released (4.16-rc3) [5eeb2ca02a2f6084fc57ae5c244a38baab07033a]
5.10-upstream-stable: N/A "Fixed before branch point"
4.19-upstream-stable: N/A "Fixed before branching point"
4.9-upstream-stable: needed
3.16-upstream-stable: ignored "Too difficult and risky to backport"
sid: released (4.15.11-1)
5.10-bullseye-security: N/A "Fixed before branching point"
4.19-buster-security: N/A "Fixed before branching point"
4.9-stretch-security: ignored "binder not enabled, and risky to backport"
3.16-jessie-security: ignored "binder not enabled, and risky to backport"