linux.git/io_uring/query.c, branch v7.3-rc1

io_uring/query: cap user size passed to copy_struct_to_user

2026-08-25T17:49:48+00:00

io_handle_query_entry() clamps hdr.size for the inbound copy_from_user()
but keeps the original user value as usize. copy_struct_to_user() uses
that usize and, when it is larger than the kernel result, clear_user()s
the trailing bytes.

As hdr.size is a __u32, a query can request nearly 4 GiB of zeroing,
including on the error path where res_size stays 0. The interface is
reachable without a ring via IORING_REGISTER_QUERY.

Reject sizes larger than PAGE_SIZE, as recommended for copy_struct_*
interfaces.

Fixes: c265ae75f900 ("io_uring: introduce io_uring querying")
Cc: stable@vger.kernel.org # 6.18+
Signed-off-by: Laxman Acharya Padhya 
Reviewed-by: Gabriel Krisman Bertazi 
Link: https://patch.msgid.link/20260821103317.91437-1-acharyalaxman8848@gmail.com
Signed-off-by: Jens Axboe

Merge tag 'for-7.3/io_uring-20260819' of git://git.kernel.org/pub/scm/linux/kernel/git/axboe/linux

2026-08-20T20:47:56+00:00

Pull io_uring update from Jens Axboe:
 "On top of the usual cleanups and fixes, the bigger items in here are:

   - zcrx work, most of it centered around adding dynamic area
     provisioning, plus a bunch of prep and cleanups leading up to it:
     scale refilling with large pages, coalesce same-niov RQEs on
     refill, separate the RQ head/tail cache lines and cache the RQ
     tail, and rework the area creation locking.

   - Fix the futex inflight accounting so that only private futex waits
     are marked inflight, and don't mark wake requests as inflight at
     all.

   - Drop the custom iov copy in the buffer select prep and msg header
     copy paths, using the generic helpers instead.

   - Fix a folio size overflow in io_vec_fill_bvec(), and account the
     pages a compound region really uses in the memmap path.

   - Fix an iovec leak in uring_cmd when the async cmd isn't recycled,
     skip the blocking task work for io_uring_cmd_issue_blocking(), and
     don't skip completion for a synchronous multishot cmd

   - Defer eventfd signaling when queued from a wakeup handler

   - Fix io-wq worker accounting when canceling creation callbacks

   - Annotate remote tasks for kcoverage"

* tag 'for-7.3/io_uring-20260819' of git://git.kernel.org/pub/scm/linux/kernel/git/axboe/linux: (30 commits)
  io_uring: Add missing include for ITER_SOURCE and ITER_DEST
  io_uring/uring_cmd: don't skip completion for a synchronous multishot cmd
  io_uring/memmap: account the pages a compound region really uses
  io_uring/zcrx: add dynamic area provisioning
  io_uring/zcrx: lock area creation with pp_lock
  io_uring/zcrx: keep array of areas
  io_uring/zcrx: move freelist lock to struct zcrx
  io_uring/zcrx: unmap under netdev lock
  io_uring/zcrx: split dmabuf unmap and release
  io_uring/zcrx: don't pass ifq_reg to area creation
  io_uring/zcrx: add helper for deriving area token
  io_uring/zcrx: don't reload skb_shinfo
  io_urint/zcrx: narrow var scope in io_zcrx_recv_skb()
  io_uring/zcrx: constify area_reg on import
  io_uring/zcrx: coalesce same-niov RQEs on refill
  io_uring/zcrx: cache RQ tail
  io_uring/zcrx: add RQ iterator
  io_uring/zcrx: move RQ head/tail to separate cache lines
  io_uring/zcrx: scale refilling with large pages
  io_uring/io-wq: fix worker accounting when canceling creation callbacks
  ...

io_uring/zcrx: move RQ head/tail to separate cache lines

2026-08-15T23:29:56+00:00

RQ head and tail are currently put into the same cache line, which can
cause false sharing problems when refill is run on another CPU. Put them
into separate cache lines.

Signed-off-by: Pavel Begunkov 
Reviewed-by: Mina Almasry 
Link: https://patch.msgid.link/f769116a3f5267f06cb9a9a819d482ddea2e0852.1786108672.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe

io_uring/zcrx: rename notif to event

2026-07-22T15:48:42+00:00

"Notification" is too long and the abbreviated version is used in
several places, which is inconsistent and more ambiguous for users.
Rename it to event, which is easier to keep consistent. To keep the
change small, only change uapi/ + do necessary fix ups, and the rest of
internals can be adjusted in the next release.

Signed-off-by: Pavel Begunkov 
Link: https://patch.msgid.link/f95ca6717da3c8d3649a1a7f0d883a563f545052.1784726895.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe

io_uring/zcrx: drop "notif" from stats struct names

2026-07-22T15:48:41+00:00

Keep zcrx statistics generic and don't stick "notif" to its uapi
definitions. Stats dosn't need to be bound to notification details,
it makes it cleaner and more readable.

Signed-off-by: Pavel Begunkov 
Link: https://patch.msgid.link/6a39676b6f71b67d3f89c6ebab7a3739873834a3.1784726895.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe

io_uring/zcrx: add shared-memory notification statistics

2026-05-26T16:42:01+00:00

Add support for an optional stats struct embedded in the refill queue
region, allowing userspace to monitor copy-fallback in real-time.

Userspace queries the stats struct size and alignment via
IO_URING_QUERY_ZCRX_NOTIF (notif_stats_size / notif_stats_alignment),
then provides a stats_offset in zcrx_notification_desc pointing to a
location within the refill queue region.

The kernel updates the stats counters in-place on every copy-fallback
event.

Signed-off-by: Clément Léger 
[pavel: rename io_uring_zcrx_notif_stats]
Signed-off-by: Pavel Begunkov 
Link: https://patch.msgid.link/f6af5a21015efea4b733b9d77aba22c637788fe4.1779189667.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe

io_uring/zcrx: declare some constants for query

2026-03-09T13:21:54+00:00

Add constants for zcrx features and supported registration flags that
can be reused by the query code. I was going to add another registration
flag, and this patch helps to avoid duplication and keeps changes
specific to zcrx files.

Signed-off-by: Pavel Begunkov 
Signed-off-by: Jens Axboe

io_uring/query: return support for custom rx page size

2026-02-15T21:55:37+00:00

Add an ability to query if the zcrx rx page size setting is available.

Note, even when the API is supported by io_uring, the registration can
still get rejected for various reasons, e.g. when the NIC or the driver
doesn't support it, when the particular specified size is unsupported,
when the memory area doesn't satisfy all requirements, etc.

Signed-off-by: Pavel Begunkov 
Signed-off-by: Jens Axboe

io_uring/query: drop unused io_handle_query_entry() ctx arg

2025-11-26T16:37:10+00:00

io_handle_query_entry() doesn't use its struct io_ring_ctx *ctx
argument. So remove it from the function and its callers.

Signed-off-by: Caleb Sander Mateos 
Signed-off-by: Jens Axboe

io_uring/query: introduce rings info query

2025-11-13T18:17:36+00:00

Same problem as with zcrx in the previous patch, the user needs to know
SQ/CQ header sizes to allocated memory before setup to use it for user
provided rings, i.e. IORING_SETUP_NO_MMAP, however that information is
only returned after registration, hence the user is guessing kernel
implementation details.

Return the header size and alignment, which is split with the same
motivation, to allow the user to know the real structure size without
alignment in case there will be more flexible placement schemes in the
future.

Signed-off-by: Pavel Begunkov 
Signed-off-by: Jens Axboe