[PATCH v3 0/2] taskstats: fix cross-netns exit listener delivery

[tjdqudcks0424]

From: 성병찬 <tjdqudcks0424@xxxxxxxxx>

CPU-mask taskstats listeners are currently identified only by a numeric
Generic Netlink port ID and exit records are sent through init_net. Since
port IDs are namespace-local, an unprivileged init_net socket can bind the
same number as a listener in another network namespace and receive that
listener's cross-UID exit record.

Patch 1 associates listener entries with the registering Generic Netlink
socket's namespace and port ID and cleans them up when that socket closes.
Patch 2 adds an acct kselftest which constructs the collision and checks the
normal listener, explicit deregistration, and unrelated-port controls.

The test was built with GCC using -Wall -Wextra and run in disposable QEMU
guests with the same userspace binary. On the unmodified baseline it reports
3 passes and 1 failure: the child-netns listener misses the victim record and
the colliding unprivileged init_net socket receives it. On the fixed kernel,
three independent clean boots each report 4 passes and no failures. No
KASAN, UBSAN, BUG, WARNING, Oops, panic, lockdep, refcount, use-after-free,
out-of-bounds, or kmemleak diagnostic was emitted during the final runs.

The exact Message-ID and lore URL of the previous public posting were not
present in the available local sent-mail or raw-mail artifacts:

Link: https://lore.kernel.org/r/20261002075842.146026-1-tjdqudcks0424@xxxxxxxxx/

Changes in v3:
- remove wording that called a private draft "v1"
- add an in-tree taskstats CPU-listener network-namespace regression test
- send the fix and selftest as a two-patch series

성병찬 (2):
  taskstats: route exit listener records through their netns
  selftests: acct: test taskstats listener netns routing

 kernel/taskstats.c                            | 135 ++-
 tools/testing/selftests/acct/Makefile         |   1 +
 .../selftests/acct/taskstats_netns_listener.c | 945 ++++++++++++++++++
 3 files changed, 1037 insertions(+), 44 deletions(-)
 create mode 100644 tools/testing/selftests/acct/taskstats_netns_listener.c


base-commit: ce1e0223d8ad4211275c82a17ed6d43ab81e13d9
-- 
2.43.0