<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux.git/net/xdp, branch v7.2</title>
<subtitle>Linux kernel source tree</subtitle>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/'/>
<entry>
<title>xsk: validate metadata when processing requests</title>
<updated>2026-08-03T23:43:54+00:00</updated>
<author>
<name>Stanislav Fomichev</name>
<email>sdf.kernel@gmail.com</email>
</author>
<published>2026-07-27T16:19:59+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=849b1664dbda1cf6c63e0fd4f9dec23782b8c851'/>
<id>849b1664dbda1cf6c63e0fd4f9dec23782b8c851</id>
<content type='text'>
The zero-copy path validates TX metadata while obtaining the descriptor
context, then reads it again later when preparing the hardware request.
User space can change the metadata between those operations and bypass the
original validation.

Validate the metadata in xsk_tx_metadata_request() and use the resulting
flags snapshot for every feature check. Read request fields once so all
zero-copy drivers process only values observed after successful
validation.

Fixes: ca4419f15abd ("xsk: Add launch time hardware offload support to XDP Tx metadata")
Cc: Cen Zhang (Microsoft) &lt;blbllhy@gmail.com&gt;
Signed-off-by: Stanislav Fomichev &lt;sdf@fomichev.me&gt;
Link: https://patch.msgid.link/20260727161959.885642-7-sdf@fomichev.me
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
The zero-copy path validates TX metadata while obtaining the descriptor
context, then reads it again later when preparing the hardware request.
User space can change the metadata between those operations and bypass the
original validation.

Validate the metadata in xsk_tx_metadata_request() and use the resulting
flags snapshot for every feature check. Read request fields once so all
zero-copy drivers process only values observed after successful
validation.

Fixes: ca4419f15abd ("xsk: Add launch time hardware offload support to XDP Tx metadata")
Cc: Cen Zhang (Microsoft) &lt;blbllhy@gmail.com&gt;
Signed-off-by: Stanislav Fomichev &lt;sdf@fomichev.me&gt;
Link: https://patch.msgid.link/20260727161959.885642-7-sdf@fomichev.me
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>xsk: validate launch-time metadata size</title>
<updated>2026-08-03T23:43:54+00:00</updated>
<author>
<name>Stanislav Fomichev</name>
<email>sdf.kernel@gmail.com</email>
</author>
<published>2026-07-27T16:19:57+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=439ce2dddf3d22129b9113a7881637256a35e936'/>
<id>439ce2dddf3d22129b9113a7881637256a35e936</id>
<content type='text'>
Launch-time metadata extends beyond the first 16 bytes of struct
xsk_tx_metadata. Reject the request when the registered metadata area does
not contain the complete field.

Snapshot the validated flags for the generic transmit path and use that
snapshot for request and completion processing, avoiding inconsistent
decisions if user space changes the flags concurrently.

Note that only xsk_skb_metadata is properly using the flags,
__xsk_buff_get_metadata ignores them. Next commits address that.

Fixes: ca4419f15abd ("xsk: Add launch time hardware offload support to XDP Tx metadata")
Cc: Cen Zhang (Microsoft) &lt;blbllhy@gmail.com&gt;
Signed-off-by: Stanislav Fomichev &lt;sdf@fomichev.me&gt;
Link: https://patch.msgid.link/20260727161959.885642-5-sdf@fomichev.me
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Launch-time metadata extends beyond the first 16 bytes of struct
xsk_tx_metadata. Reject the request when the registered metadata area does
not contain the complete field.

Snapshot the validated flags for the generic transmit path and use that
snapshot for request and completion processing, avoiding inconsistent
decisions if user space changes the flags concurrently.

Note that only xsk_skb_metadata is properly using the flags,
__xsk_buff_get_metadata ignores them. Next commits address that.

Fixes: ca4419f15abd ("xsk: Add launch time hardware offload support to XDP Tx metadata")
Cc: Cen Zhang (Microsoft) &lt;blbllhy@gmail.com&gt;
Signed-off-by: Stanislav Fomichev &lt;sdf@fomichev.me&gt;
Link: https://patch.msgid.link/20260727161959.885642-5-sdf@fomichev.me
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>xsk: clear metadata pointer when no timestamp is requested</title>
<updated>2026-08-03T23:43:53+00:00</updated>
<author>
<name>Stanislav Fomichev</name>
<email>sdf.kernel@gmail.com</email>
</author>
<published>2026-07-27T16:19:56+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=9f60a67df8d3c862503bee62bada8e7089cba438'/>
<id>9f60a67df8d3c862503bee62bada8e7089cba438</id>
<content type='text'>
User space can change metadata flags after request processing. Rereading
them during completion can therefore make the kernel write a timestamp
that was not requested when the packet was submitted.

Clear the metadata pointer during request processing unless timestamp
completion is requested. Completion handling can then use the pointer
itself instead of rereading the flags.

On the mlx5 multi-packet WQE path metadata is evaluated per batch:
xsk_tx_metadata_request() runs only for the descriptor that starts a
session, just like the checksum offload that is applied once through the
shared WQE. Only that descriptor's pointer is reset, so completion
handling can record a timestamp for the other descriptors of the session
regardless of their own XDP_TXMD_FLAGS_TIMESTAMP bit. The write stays
inside the metadata area; the single-WQE, other zero-copy, and generic
paths reset the pointer per descriptor and are unaffected.

Fixes: ca4419f15abd ("xsk: Add launch time hardware offload support to XDP Tx metadata")
Cc: Cen Zhang (Microsoft) &lt;blbllhy@gmail.com&gt;
Signed-off-by: Stanislav Fomichev &lt;sdf@fomichev.me&gt;
Link: https://patch.msgid.link/20260727161959.885642-4-sdf@fomichev.me
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
User space can change metadata flags after request processing. Rereading
them during completion can therefore make the kernel write a timestamp
that was not requested when the packet was submitted.

Clear the metadata pointer during request processing unless timestamp
completion is requested. Completion handling can then use the pointer
itself instead of rereading the flags.

On the mlx5 multi-packet WQE path metadata is evaluated per batch:
xsk_tx_metadata_request() runs only for the descriptor that starts a
session, just like the checksum offload that is applied once through the
shared WQE. Only that descriptor's pointer is reset, so completion
handling can record a timestamp for the other descriptors of the session
regardless of their own XDP_TXMD_FLAGS_TIMESTAMP bit. The write stays
inside the metadata area; the single-WQE, other zero-copy, and generic
paths reset the pointer per descriptor and are unaffected.

Fixes: ca4419f15abd ("xsk: Add launch time hardware offload support to XDP Tx metadata")
Cc: Cen Zhang (Microsoft) &lt;blbllhy@gmail.com&gt;
Signed-off-by: Stanislav Fomichev &lt;sdf@fomichev.me&gt;
Link: https://patch.msgid.link/20260727161959.885642-4-sdf@fomichev.me
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>xsk: require at least 16 bytes of TX metadata</title>
<updated>2026-08-03T23:43:53+00:00</updated>
<author>
<name>Stanislav Fomichev</name>
<email>sdf.kernel@gmail.com</email>
</author>
<published>2026-07-27T16:19:54+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=1bb30b181d9f0484e141f8411e15ed906d5c6780'/>
<id>1bb30b181d9f0484e141f8411e15ed906d5c6780</id>
<content type='text'>
AF_XDP accepts a TX metadata length as small as eight bytes, but every
supported request needs the flags plus at least one eight-byte request
field. Such short metadata also lets the kernel read beyond the registered
area.

Require 16 bytes rather than sizeof(struct xsk_tx_metadata) to preserve
compatibility with applications that do not use launch-time metadata.

Fixes: 341ac980eab9 ("xsk: Support tx_metadata_len")
Reported-by: AutonomousCodeSecurity@microsoft.com
Reported-by: Cen Zhang (Microsoft) &lt;blbllhy@gmail.com&gt;
Link: https://lore.kernel.org/netdev/20260720155210.34229-1-blbllhy@gmail.com/
Signed-off-by: Stanislav Fomichev &lt;sdf@fomichev.me&gt;
Link: https://patch.msgid.link/20260727161959.885642-2-sdf@fomichev.me
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
AF_XDP accepts a TX metadata length as small as eight bytes, but every
supported request needs the flags plus at least one eight-byte request
field. Such short metadata also lets the kernel read beyond the registered
area.

Require 16 bytes rather than sizeof(struct xsk_tx_metadata) to preserve
compatibility with applications that do not use launch-time metadata.

Fixes: 341ac980eab9 ("xsk: Support tx_metadata_len")
Reported-by: AutonomousCodeSecurity@microsoft.com
Reported-by: Cen Zhang (Microsoft) &lt;blbllhy@gmail.com&gt;
Link: https://lore.kernel.org/netdev/20260720155210.34229-1-blbllhy@gmail.com/
Signed-off-by: Stanislav Fomichev &lt;sdf@fomichev.me&gt;
Link: https://patch.msgid.link/20260727161959.885642-2-sdf@fomichev.me
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>xsk: reclaim invalid Tx descriptors in ZC batch path</title>
<updated>2026-07-24T22:12:14+00:00</updated>
<author>
<name>Maciej Fijalkowski</name>
<email>maciej.fijalkowski@intel.com</email>
</author>
<published>2026-07-19T13:56:07+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=72f2b4516faf55d4dfac2414649d3cffa5fd2c5e'/>
<id>72f2b4516faf55d4dfac2414649d3cffa5fd2c5e</id>
<content type='text'>
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 &lt;kernelxing@tencent.com&gt;
Signed-off-by: Maciej Fijalkowski &lt;maciej.fijalkowski@intel.com&gt;
Acked-by: Stanislav Fomichev &lt;sdf@fomichev.me&gt;
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 &lt;kuba@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
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 &lt;kernelxing@tencent.com&gt;
Signed-off-by: Maciej Fijalkowski &lt;maciej.fijalkowski@intel.com&gt;
Acked-by: Stanislav Fomichev &lt;sdf@fomichev.me&gt;
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 &lt;kuba@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>xsk: provide sufficient space in pool-&gt;tx_descs</title>
<updated>2026-07-24T22:12:14+00:00</updated>
<author>
<name>Maciej Fijalkowski</name>
<email>maciej.fijalkowski@intel.com</email>
</author>
<published>2026-07-19T13:56:06+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=08c9a8e794b4694c100dafcb80e069e29ad81b64'/>
<id>08c9a8e794b4694c100dafcb80e069e29ad81b64</id>
<content type='text'>
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 &lt;kernelxing@tencent.com&gt;
Signed-off-by: Maciej Fijalkowski &lt;maciej.fijalkowski@intel.com&gt;
Acked-by: Stanislav Fomichev &lt;sdf@fomichev.me&gt;
Link: https://patch.msgid.link/20260719135609.147823-4-maciej.fijalkowski@intel.com
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
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 &lt;kernelxing@tencent.com&gt;
Signed-off-by: Maciej Fijalkowski &lt;maciej.fijalkowski@intel.com&gt;
Acked-by: Stanislav Fomichev &lt;sdf@fomichev.me&gt;
Link: https://patch.msgid.link/20260719135609.147823-4-maciej.fijalkowski@intel.com
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>xsk: drain continuation descs after overflow in xsk_build_skb()</title>
<updated>2026-07-24T22:12:14+00:00</updated>
<author>
<name>Jason Xing</name>
<email>kernelxing@tencent.com</email>
</author>
<published>2026-07-19T13:56:05+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=bd44a6dcd4248883de90f5dad53ae80066e27096'/>
<id>bd44a6dcd4248883de90f5dad53ae80066e27096</id>
<content type='text'>
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 &lt;kernelxing@tencent.com&gt;
Co-developed-by: Maciej Fijalkowski &lt;maciej.fijalkowski@intel.com&gt; # wrapped cq addr submission onto routine
Signed-off-by: Maciej Fijalkowski &lt;maciej.fijalkowski@intel.com&gt;
Signed-off-by: Jason Xing &lt;kernelxing@tencent.com&gt;
Acked-by: Stanislav Fomichev &lt;sdf@fomichev.me&gt;
Link: https://patch.msgid.link/20260719135609.147823-3-maciej.fijalkowski@intel.com
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
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 &lt;kernelxing@tencent.com&gt;
Co-developed-by: Maciej Fijalkowski &lt;maciej.fijalkowski@intel.com&gt; # wrapped cq addr submission onto routine
Signed-off-by: Maciej Fijalkowski &lt;maciej.fijalkowski@intel.com&gt;
Signed-off-by: Jason Xing &lt;kernelxing@tencent.com&gt;
Acked-by: Stanislav Fomichev &lt;sdf@fomichev.me&gt;
Link: https://patch.msgid.link/20260719135609.147823-3-maciej.fijalkowski@intel.com
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>xsk: fix buffer leak in xsk_drop_skb() for AF_XDP multi-buffer Tx</title>
<updated>2026-07-24T22:12:14+00:00</updated>
<author>
<name>Jason Xing</name>
<email>kernelxing@tencent.com</email>
</author>
<published>2026-07-19T13:56:04+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=a3c8382ebce4780c6b3ace2c09bc342313ac0186'/>
<id>a3c8382ebce4780c6b3ace2c09bc342313ac0186</id>
<content type='text'>
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-&gt;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-&gt;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 &lt;maciej.fijalkowski@intel.com&gt;
Signed-off-by: Jason Xing &lt;kernelxing@tencent.com&gt;
Acked-by: Stanislav Fomichev &lt;sdf@fomichev.me&gt;
Link: https://patch.msgid.link/20260719135609.147823-2-maciej.fijalkowski@intel.com
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
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-&gt;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-&gt;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 &lt;maciej.fijalkowski@intel.com&gt;
Signed-off-by: Jason Xing &lt;kernelxing@tencent.com&gt;
Acked-by: Stanislav Fomichev &lt;sdf@fomichev.me&gt;
Link: https://patch.msgid.link/20260719135609.147823-2-maciej.fijalkowski@intel.com
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net</title>
<updated>2026-06-04T22:29:04+00:00</updated>
<author>
<name>Jakub Kicinski</name>
<email>kuba@kernel.org</email>
</author>
<published>2026-06-04T22:26:27+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=8d72997dab65b1e9e3220302e26eaecd9b99c02f'/>
<id>8d72997dab65b1e9e3220302e26eaecd9b99c02f</id>
<content type='text'>
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 &lt;kuba@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
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 &lt;kuba@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>net: rename netdev_ops_assert_locked()</title>
<updated>2026-06-04T21:04:55+00:00</updated>
<author>
<name>Jakub Kicinski</name>
<email>kuba@kernel.org</email>
</author>
<published>2026-06-03T01:28:30+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=251bc9db88fb351ea2dfbd976c4e6aaae6507a91'/>
<id>251bc9db88fb351ea2dfbd976c4e6aaae6507a91</id>
<content type='text'>
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 &lt;jakub@cloudflare.com&gt;
Reviewed-by: Nicolai Buchwitz &lt;nb@tipi-net.de&gt;
Reviewed-by: Jakub Sitnicki &lt;jakub@cloudflare.com&gt;
Acked-by: Stanislav Fomichev &lt;sdf@fomichev.me&gt;
Link: https://patch.msgid.link/20260603012840.2254293-2-kuba@kernel.org
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
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 &lt;jakub@cloudflare.com&gt;
Reviewed-by: Nicolai Buchwitz &lt;nb@tipi-net.de&gt;
Reviewed-by: Jakub Sitnicki &lt;jakub@cloudflare.com&gt;
Acked-by: Stanislav Fomichev &lt;sdf@fomichev.me&gt;
Link: https://patch.msgid.link/20260603012840.2254293-2-kuba@kernel.org
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
</pre>
</div>
</content>
</entry>
</feed>
