Description: anon_vma UAF through bogus merge of VMAs caused by double-reuse of leaf anon_vma because of ->degree misinterpretation
References:
 https://bugs.chromium.org/p/project-zero/issues/detail?id=2351
 https://googleprojectzero.blogspot.com/2022/12/exploiting-CVE-2022-42703-bringing-back-the-stack-attack.html
Notes:
Bugs:
upstream: released (6.0-rc4) [2555283eb40df89945557273121e9393ef9b542b]
5.10-upstream-stable: released (5.10.141) [98f401d36396134c0c86e9e3bd00b6b6b028b521]
4.19-upstream-stable: released (4.19.257) [6dbfc25d68d922736381988d64156a649ccf7bf1]
sid: released (5.19.11-1)
5.10-bullseye-security: released (4.19.140-1) [bugfix/all/mm-rmap-fix-anon_vma-degree-ambiguity-leading-to-double-reuse.patch]
4.19-buster-security: released (4.19.260-1)