linux-toradex.git/net/xdp, branch master

xsk: reclaim invalid Tx descriptors in ZC batch path

2026-07-24T22:12:14+00:00

The zero-copy Tx batch parser stops when it encounters an invalid
descriptor. If this happens after one or more continuation descriptors,
the Tx consumer can be advanced past fragments that are neither submitted
to the driver nor returned to userspace through the completion ring.

A similar problem occurs when a packet exceeds xdp_zc_max_segs. The
descriptors consumed up to the limit are released without completion, and
the remaining continuation descriptors can subsequently be interpreted
as the beginning of another packet.

Parse Tx batches in packet units and distinguish descriptors belonging to
complete valid packets from descriptors consumed while draining an
invalid or oversized packet. Return the former to the driver and append
the latter to the CQ address area so userspace can reclaim their UMEM
frames.

Treat a standalone invalid descriptor as a one-descriptor reclaim-only
packet. Advancing the Tx-ring consumer releases the ring slot, but does
not by itself return ownership of the referenced UMEM frame to userspace.

Once draining starts, continue until the packet's end-of-packet
descriptor is consumed. Preserve the drain state on the socket when EOP
has not yet been supplied, so draining can continue during a later call.
Leave incomplete but otherwise valid packets on the Tx ring.

Shared-UMEM pools using multi-buffer Tx also need packet-framed parsing.
Walk their Tx sockets one packet at a time, preserving the existing
per-socket fairness scheme, instead of using the legacy one-descriptor
fallback. Keep that fallback for shared pools that do not use
multi-buffer Tx. Since the drain state is maintained per socket and both
the singular and shared paths can resume an interrupted drain, changing
the socket list from singular to shared requires no special bind-time
transition.

CQ entries are positional, and drivers may complete only part of the Tx
work returned by xsk_tx_peek_release_desc_batch(). Therefore, reclaim-only
entries cannot be published immediately when earlier driver-visible
descriptors are still outstanding.

Track the number of driver-visible CQ entries preceding the reclaim
entries. Let xsk_tx_completed() publish partial hardware Tx completions,
and publish the reclaim entries only after every earlier Tx descriptor
has completed. Complete a reclaim-only batch immediately when there is no
driver-visible work in front of it, and prevent another Tx batch from
being appended while reclaim entries remain pending.

Also cap batch processing by the size of the pool's temporary descriptor
array, as Tx rings belonging to sockets sharing a UMEM may have different
sizes.

This ensures that every invalid Tx descriptor consumed by the ZC batch
path is either submitted to the driver as part of a valid packet or
returned to userspace without violating CQ completion ordering.

Reviewed-by: Jason Xing 
Signed-off-by: Maciej Fijalkowski 
Acked-by: Stanislav Fomichev 
Fixes: cf24f5a5feea ("xsk: add support for AF_XDP multi-buffer on Tx path")
Link: https://patch.msgid.link/20260719135609.147823-5-maciej.fijalkowski@intel.com
Signed-off-by: Jakub Kicinski

xsk: provide sufficient space in pool->tx_descs

2026-07-24T22:12:14+00:00

The temporary Tx descriptor array in an XSK buffer pool is currently
sized from the Tx ring of the socket that creates the pool.

This is insufficient for shared-UMEM Tx. A later socket may have a
larger Tx ring and submit a valid multi-buffer packet containing more
descriptors than the first socket's ring, while still remaining within
the device's xdp_zc_max_segs limit.

A packet-framed batch parser bounded by the temporary array cannot reach
the end-of-packet descriptor in that case. It leaves the packet on the
Tx ring and encounters the same packet on every subsequent attempt,
stalling Tx processing for that socket.

Size the temporary descriptor array to the larger of the first Tx ring
and the device's xdp_zc_max_segs capability. This keeps the array large
enough to inspect one maximum-sized valid packet. Larger shared Tx rings
do not require further resizing, as they can be processed over multiple
batches.

Following commit will actually address the data path side.

Fixes: d5581966040f ("xsk: support ZC Tx multi-buffer in batch API")
Reviewed-by: Jason Xing 
Signed-off-by: Maciej Fijalkowski 
Acked-by: Stanislav Fomichev 
Link: https://patch.msgid.link/20260719135609.147823-4-maciej.fijalkowski@intel.com
Signed-off-by: Jakub Kicinski

xsk: drain continuation descs after overflow in xsk_build_skb()

2026-07-24T22:12:14+00:00

Fix generic xmit path multi-buffer logic when packets are either too big
(count of descriptors exceed MAX_SKB_FRAGS) or an invalid descriptor is
included in fragmented packet. Introduce xdp_sock::drain_cont and act
upon this flag - when it is set, keep on consuming descriptors from
AF_XDP Tx ring and put them directly onto Cq. Previously these
descriptors were silently lost and could never be reached again.

Fixes: cf24f5a5feea ("xsk: add support for AF_XDP multi-buffer on Tx path")
Closes: https://lore.kernel.org/all/20260425041726.85FB3C2BCB2@smtp.kernel.org/
Reviewed-by: Jason Xing 
Co-developed-by: Maciej Fijalkowski  # wrapped cq addr submission onto routine
Signed-off-by: Maciej Fijalkowski 
Signed-off-by: Jason Xing 
Acked-by: Stanislav Fomichev 
Link: https://patch.msgid.link/20260719135609.147823-3-maciej.fijalkowski@intel.com
Signed-off-by: Jakub Kicinski

xsk: fix buffer leak in xsk_drop_skb() for AF_XDP multi-buffer Tx

2026-07-24T22:12:14+00:00

This patch is inspired by the check[1] from sashiko. It says when
overflow happens, the address of cq to be published is invalid.
Actually the severer thing is the whole process of publishing the
address of cq in this particular case is not right: it should truely
publish the address and advance the cached_prod in cq as long as it
reads descriptors from txq.

The following is the full analysis.
xsk_drop_skb() is called in three places, which all discard a partially
built multi-buffer skb:
1) xsk_build_skb() -EOVERFLOW error path: packet exceeds MAX_SKB_FRAGS
2) __xsk_generic_xmit() post-loop cleanup: an invalid descriptor in
   the TX ring prevents the partial packet from completing
3) xsk_release(): socket close while xs->skb holds an incomplete packet

In all three cases, the TX descriptors for the already-processed frags
have been consumed from the TX ring (xskq_cons_release), and CQ slots
have been reserved. However, xsk_drop_skb() calls xsk_consume_skb()
which cancels the CQ reservations via xsk_cq_cancel_locked(). Since
the buffer addresses never appear in the completion queue, userspace
permanently loses track of these buffers.

Fix this by letting consume_skb() trigger the existing xsk_destruct_skb
destructor, which already submits buffer addresses to the CQ via
xsk_cq_submit_addr_locked().

Note that cancelling the descriptors back to the TX ring (via
xskq_cons_cancel_n) is not a appropriate option because an oversized
packet that always exceeds MAX_SKB_FRAGS would be retried indefinitely,
which is an obviously deadlock bug in the TX path.

Also move the desc->addr assignment in xsk_build_skb() above the
overflow check so that the current descriptor's address is recorded
before a potential -EOVERFLOW jump to free_err, consistent with the
zerocopy path in xsk_build_skb_zerocopy().

[1]: https://lore.kernel.org/all/20260425041726.85FB3C2BCB2@smtp.kernel.org/

Fixes: cf24f5a5feea ("xsk: add support for AF_XDP multi-buffer on Tx path")
Acked-by: Maciej Fijalkowski 
Signed-off-by: Jason Xing 
Acked-by: Stanislav Fomichev 
Link: https://patch.msgid.link/20260719135609.147823-2-maciej.fijalkowski@intel.com
Signed-off-by: Jakub Kicinski

Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net

2026-06-04T22:29:04+00:00

Cross-merge networking fixes after downstream PR (net-7.1-rc7).

Silent conflicts:

net/wireless/nl80211.c
  cb9959ab5f99 ("wifi: cfg80211: enforce HE/EHT cap/oper consistency")
  a384ae969902 ("wifi: cfg80211: move AP HT/VHT/... operation to beacon info")
https://lore.kernel.org/aiGJDaHV4UlCexIQ@sirena.org.uk

Conflicts:

drivers/net/wireless/intel/iwlwifi/mld/ap.c
  a342c99cb70d ("wifi: iwlwifi: mld: honor BSS_CHANGED_BEACON_ENABLED")
  9bf1b409afc7 ("wifi: iwlwifi: mld: send tx power constraints before link activation")
https://lore.kernel.org/ah2bfedhV45ZxMO8@sirena.org.uk

drivers/net/wireless/intel/iwlwifi/pcie/drv.c
  093305d801fa ("wifi: iwlwifi: pcie: simplify the resume flow if fast resume is not used")
  e2323929a68a ("wifi: iwlwifi: pcie: add debug print for resume flow if powered off")
https://lore.kernel.org/ah2bfedhV45ZxMO8@sirena.org.uk

Adjacent changes:

drivers/net/ethernet/airoha/airoha_eth.c
  b38cae85d1c4 ("net: airoha: Fix use-after-free in metadata dst teardown")
  ec6c391bcca7 ("net: airoha: Introduce airoha_gdm_dev struct")

drivers/net/ethernet/microchip/lan743x_main.c
  8173d22b211f ("net: lan743x: permit VLAN-tagged packets up to configured MTU")
  e3c6508a46f5 ("net: lan743x: avoid netdev-based logging before netdev registration")

Signed-off-by: Jakub Kicinski

net: rename netdev_ops_assert_locked()

2026-06-04T21:04:55+00:00

Jakub suggests renaming the existing assert to match
the netdev_lock_ops_compat() semantics.

We want netdev_assert_locked_ops() to mean - if the driver
is ops locked - check that it's holding the device lock.

The existing helper check for either ops lock or rtnl_lock,
which is the locking behavior of netdev_lock_ops_compat().

The reason for naming divergence is likely that
netdev_ops_assert_locked() predated the _compat() helpers.

Suggested-by: Jakub Sitnicki 
Reviewed-by: Nicolai Buchwitz 
Reviewed-by: Jakub Sitnicki 
Acked-by: Stanislav Fomichev 
Link: https://patch.msgid.link/20260603012840.2254293-2-kuba@kernel.org
Signed-off-by: Jakub Kicinski

xsk: cache csum_start/csum_offset to fix TOCTOU in xsk_skb_metadata()

2026-06-04T00:45:42+00:00

The TX metadata area resides in the UMEM buffer which is memory-mapped
and concurrently writable by userspace. In xsk_skb_metadata(),
csum_start and csum_offset are read from shared memory for bounds
validation, then read again for skb assignment. A malicious userspace
application can race to overwrite these values between the two reads,
bypassing the bounds check and causing out-of-bounds memory access
during checksum computation in the transmit path.

Fix this by reading csum_start and csum_offset into local variables
once, then using the local copies for both validation and assignment.

Note that other metadata fields (flags, launch_time) and the cached
csum fields may be mutually inconsistent due to concurrent userspace
writes, but this is benign: the only security-critical invariant is
that each field's validated value is the same one used, which local
caching guarantees.

Closes: https://lore.kernel.org/all/20260503200927.73EA1C2BCB4@smtp.kernel.org/
Reviewed-by: Maciej Fijalkowski 
Signed-off-by: Jason Xing 
Acked-by: Stanislav Fomichev 
Fixes: 48eb03dd2630 ("xsk: Add TX timestamp and TX checksum offload support")
Link: https://patch.msgid.link/20260530042630.80626-1-kerneljasonxing@gmail.com
Signed-off-by: Jakub Kicinski

xdp: convert to getsockopt_iter

2026-05-22T18:11:09+00:00

Convert XDP socket's getsockopt implementation to use the new
getsockopt_iter callback with sockopt_t.

Key changes:
- Replace (char __user *optval, int __user *optlen) with sockopt_t *opt
- Use opt->optlen for buffer length (input) and returned size (output)
- Use copy_to_iter() instead of put_user()/copy_to_user()

Acked-by: Stanislav Fomichev 
Signed-off-by: Breno Leitao 
Link: https://patch.msgid.link/20260520-getsock_four-v3-3-b8c0b16b7780@debian.org
Signed-off-by: Jakub Kicinski

Merge tag 'bpf-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf

2026-05-10T01:42:54+00:00

Pull bpf fixes from Alexei Starovoitov:

 - Fix sk_local_storage diag dump via netlink (Amery Hung)

 - Fix off-by-one in arena direct-value access (Junyoung Jang)

 - Reject TCP_NODELAY in bpf-tcp congestion control (KaFai Wan)

 - Fix type confusion in bpf_*_sock() (Kuniyuki Iwashima)

 - Reject TX-only AF_XDP sockets (Linpu Yu)

 - Don't run arg-tracking analysis twice on main subprog (Paul Chaignon)

 - Fix NULL pointer dereference in bpf_sk_storage_clone and fib lookup
   (Weiming Shi)

* tag 'bpf-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf:
  bpf: Fix off-by-one boundary validation in arena direct-value access
  xskmap: reject TX-only AF_XDP sockets
  bpf: Don't run arg-tracking analysis twice on main subprog
  bpf: Free reuseport cBPF prog after RCU grace period.
  bpf: tcp: Fix type confusion in sol_tcp_sockopt().
  bpf: tcp: Fix type confusion in bpf_skc_to_tcp6_sock().
  bpf: tcp: Fix type confusion in bpf_skc_to_tcp_sock().
  mptcp: bpf: Fix type confusion in bpf_mptcp_sock_from_subflow()
  selftest: bpf: Add test for bpf_tcp_sock() and RAW socket.
  bpf: tcp: Fix type confusion in bpf_tcp_sock().
  tools/headers: Regenerate stddef.h to fix BPF selftests
  bpf: Fix sk_local_storage diag dumping uninitialized special fields
  bpf: Fix NULL pointer dereference in bpf_skb_fib_lookup()
  sockmap: Fix sk_psock_drop() race vs sock_map_{unhash,close,destroy}().
  bpf: Fix NULL pointer dereference in bpf_sk_storage_clone and diag paths
  selftests/bpf: Verify bpf-tcp-cc rejects TCP_NODELAY
  selftests/bpf: Test TCP_NODELAY in TCP hdr opt callbacks
  bpf: Reject TCP_NODELAY in bpf-tcp-cc
  bpf: Reject TCP_NODELAY in TCP header option callbacks

xskmap: reject TX-only AF_XDP sockets

2026-05-09T23:17:01+00:00

XSKMAP entries are used as redirect targets for incoming XDP frames.
A TX-only AF_XDP socket lacks an Rx ring and cannot handle redirected
traffic, but xsk_map_update_elem() currently allows such sockets to
be inserted into the map.

Redirecting packets to such a socket on the veth generic-XDP path
causes a kernel crash in xsk_generic_rcv().

This became possible after xsk_is_setup_for_bpf_map() was removed from
the XSKMAP update path, which allowed bound TX-only sockets to be
inserted into the map.

Reject TX-only sockets during XSKMAP updates to avoid the crash.
They remain fully operational for pure Tx purposes outside XSKMAP.

Fixes: 968be23ceaca ("xsk: Fix possible segfault at xskmap entry insertion")
Reported-by: Juefei Pu 
Reported-by: Yuan Tan 
Reported-by: Xin Liu 
Signed-off-by: Yifan Wu 
Signed-off-by: Linpu Yu 
Reviewed-by: Jason Xing 
Link: https://lore.kernel.org/r/20260508144344.694-1-linpu5433@gmail.com
Signed-off-by: Alexei Starovoitov