[PATCH net-next v2 0/4] net: prevent mixing incompatible memory providers in skbs

[Mina Almasry <almasrymina@google.com>]

Enforce that all fragments in a nonlinear skb come from compatible
memory providers (and for devmem, the exact same binding).

Patch 1 fixes skb->unreadable propagation in skb_split() and skb_shift().
Patch 2 stores mp_priv directly inside struct net_iov.
Patch 3 adds skb_has_net_iovs(), skb_mem_provider_compat(), and
skb_frags_can_coalesce().
Patch 4 enforces provider/binding compatibility across TX, TCP, GRO,
IP defrag, skb_shift(), and skb_try_coalesce().

v1 -> v2:
- Generalize the check across TX, TCP collapse, GRO, IP defrag,
  skb_shift(), and skb_try_coalesce() by storing mp_priv directly in
  struct net_iov and introducing skb_frags_can_coalesce().
- Fix skb->unreadable propagation in skb_split() and skb_shift().
- Add KUnit coverage for cross-provider and cross-binding rejection.
- v1: https://lore.kernel.org/netdev/20261008034027.1403188-1-almasrymina@google.com/


Mina Almasry (4):
  net: fix skb->unreadable propagation in skb_split() and skb_shift()
  netmem: store memory provider private pointer directly in struct
    net_iov
  net: add skb_frags_can_coalesce() helper
  net: prevent mixing frags from different memory providers or bindings

 include/linux/skbuff.h   | 58 ++++++++++++++++++++++++++++++++++++++++
 include/net/netmem.h     | 15 +++++++++--
 include/net/tcp.h        |  5 ++--
 io_uring/zcrx.c          |  2 +-
 net/core/datagram.c      |  4 +--
 net/core/dev.c           | 14 +++-------
 net/core/devmem.c        |  3 ++-
 net/core/devmem.h        | 25 +++++++++++++++--
 net/core/gro.c           | 16 +++++------
 net/core/net_test.c      | 34 +++++++++++++++++------
 net/core/skbuff.c        | 34 ++++++++++++-----------
 net/ipv4/inet_fragment.c |  3 +++
 net/ipv4/tcp.c           |  2 +-
 net/ipv4/tcp_output.c    |  3 +++
 14 files changed, 163 insertions(+), 55 deletions(-)


base-commit: 4dd16e31135ea8437a720222df34e8745f385d6d
-- 
2.56.0.385.gac671c819a-goog