[PATCH net v3 0/3] net: hsr: fix shared-skb mutations in the forwarding path

[Xin Xie <xiexinet@gmail.com>]

Two existing HSR/PRP forwarding paths modify data shared by multiple
skbs. One changes RedBox interlink source addresses, and the other
updates per-egress HSR path or PRP LAN IDs. A later consumer can then
observe another consumer's value.

Patch 1 makes interlink address substitution private. Patch 2 uses one
clone/COW helper for tagged HSR/PRP frames and both hardware
tag-insertion branches. Patch 3 adds regressions for both corruptions.

The series is independent of the posted GRO/GSO v5 series:
https://lore.kernel.org/all/20260807140751.1351-1-xiexinet@gmail.com/
Both orders apply to current net. On current net-next, patch 3 needs
git am -3 because hsr_prp_redbox.sh is already in the same Makefile
block; the merged list remains sorted and validates.

Validation:
- the targeted test fails both cases on the base and passes on the
  candidate
- the affected HSR/PRP regression tests pass
- base-versus-candidate W=1 allmodconfig and allyesconfig add no
  diagnostics
- no TAG_INS hardware was available; those branches have source
  review only

Changes since v2, including official Sashiko dispositions:
- use a shared clone/COW helper and cover both TAG_INS branches
- correct the helper comment and interlink eligibility wording
- fix HSR LSDU encoding, capture draining, and result aggregation
- defer the existing dev->stats races per Paolo
- leave VLAN/non-linear receive parsing and receive-side tap aliases
  unchanged

Previous postings:
v2: https://lore.kernel.org/all/20260802202504.2962-1-xiexinet@gmail.com/
v1: https://lore.kernel.org/all/20260728143604.26-1-xiexinet@gmail.com/

Xin Xie (3):
  net: hsr: privatize interlink-bound skbs before address mutation
  net: hsr: return private clones from the tagged-frame helpers
  selftests: net: hsr: add shared-mutation regression test

 net/hsr/hsr_forward.c                         |  65 ++++-
 tools/testing/selftests/net/hsr/Makefile      |   1 +
 .../selftests/net/hsr/hsr_shared_mutation.sh  | 242 ++++++++++++++++++
 3 files changed, 299 insertions(+), 9 deletions(-)
 create mode 100755 tools/testing/selftests/net/hsr/hsr_shared_mutation.sh


base-commit: 594d905195024b228c962627ae5ae7c17bd582a4
-- 
2.43.0