[SRU Bionic/Focal/Hirsute/Impish/hwe-5.8/oem-5.10/oem-5.13 0/1] CVE-2021-3759

[Thadeu Lima de Souza Cascardo]

[Impact]
IPC objects are unaccounted as memcg limits, breaking them and leading
to DoS (OOM outside the memory cgroup).

[Backports]
The allocation calls have changed from kvmalloc from kmalloc or kmalloc to
kzalloc. I kept them as they were, just changing the GPF_KERNEL to
GPF_KERNEL_ACCOUNT as from the original commit.

[Test case]
I did a large semget loop. When the process was on a memcg, without the fix,
processes from outside the cgroup would be killed, whereas, with the fix,
only processes whithin the cgroup would be OOM-killed.

[Potential regression]
IPC requests may be refused when processes are restricted to memory cgroups.

Vasily Averin (1):
  memcg: enable accounting of ipc resources

 ipc/msg.c | 2 +-
 ipc/sem.c | 9 +++++----
 ipc/shm.c | 2 +-
 3 files changed, 7 insertions(+), 6 deletions(-)

-- 
2.30.2