[SRU][J][PATCH 0/1] CVE-2022-49651

[Cengiz Can]

https://ubuntu.com/security/CVE-2022-49651

[ Impact ]

In the Linux kernel, the following vulnerability has been resolved:

srcu: Tighten cleanup_srcu_struct() GP checks

Currently, cleanup_srcu_struct() checks for a grace period in progress, but it
does not check for a grace period that has not yet started but which might
start at any time. Such a situation could result in a use-after-free bug, so
this commit adds a check for a grace period that is needed but not yet started
to cleanup_srcu_struct().

[ Fix ]

jammy/linux: clean cherry-pick of 8ed00760203d

[ Test Plan ]

Build and boot tested.

[ Where Problems Could Occur ]

This change touches the SRCU (Sleepable RCU) teardown path in the core
kernel, so it is architecture- and hardware-independent and affects any
system running jammy/linux. A bad fix could add a false-positive warning or
stall during cleanup_srcu_struct(), which would primarily impact kernel
subsystems and loadable modules that dynamically create and destroy SRCU
structures (for example when modules are unloaded). Workloads that never
tear down SRCU structures at runtime, and userspace applications generally,
are not affected.

[ Other Info ]

Kybele flow-v11-21-g0f091652. Reference: 7095cf46/v1