CVE-2026-97619: io_uring/rw: end write accounting from ->ki_complete

CVE-2026-97619: io_uring/rw: end write accounting from ->ki_complete

[Greg Kroah-Hartman]

From: Greg Kroah-Hartman <gregkh@kernel.org>

Description
===========

In the Linux kernel, the following vulnerability has been resolved:

io_uring/rw: end write accounting from ->ki_complete

Commit b000145e9907 moved both the fsnotify calls and the write
accounting out of the kiocb completion handler and into the
io_req_rw_complete() task_work. However, only the fsnotify part actually
needed to move as it may sleep. Ending the write accounting is just a
percpu_up_read() on the superblock writers sem.

Deferring it is a problem, because it makes dropping SB_FREEZE_WRITE
protection depend on the ring owner getting to running task_work. But
the task may be blocked in freeze_super(), causing it to never get to
that:

  task                             io-wq worker
  --------------------------------------------------------------
  io_write()
    io_kiocb_start_write()         (takes sb_writers, hidden from
                                    lockdep by __sb_writers_release)
    write_iter() -> -EIOCBQUEUED
  ioctl(FS_IOC_SHUTDOWN)
    bdev_freeze()
      freeze_super()
        percpu_down_write()        <- waits for the reader above
                                   io_write()
                                     kiocb_start_write()
                                       percpu_down_read()  <- queued
                                                              behind the
                                                              writer
  <bio completes>
    io_complete_rw()
      queues io_req_rw_complete()  <- never runs, task is in D state

End the write from io_complete_rw() instead, and leave only the fsnotify
calls in task_work.

The Linux kernel CVE team has assigned CVE-2026-97619 to this issue.


Affected and fixed versions
===========================

	Issue introduced in 6.1 with commit b000145e9907809406d8164c3b2b8861d95aecd1 and fixed in 6.18.53 with commit cc580cee4dfa2ec9099c30ecbd4d804cbb996432
	Issue introduced in 6.1 with commit b000145e9907809406d8164c3b2b8861d95aecd1 and fixed in 7.2.7 with commit 055d43a1233edbd80e558889258105ce63051bcd
	Issue introduced in 6.1 with commit b000145e9907809406d8164c3b2b8861d95aecd1 and fixed in 7.3-rc3 with commit 796aa0547557e63338657ed1c487906f9fac4c73
	Issue introduced in 5.10.165 with commit ea2e6286e3e89a115ae554e20ba9aec2b2e1ddff
	Issue introduced in 5.15.90 with commit 89a410dbd0f159ddd308f19d6eb682fc753e4771
	Issue introduced in 6.0.3 with commit 2a853c206e553dd9c0a55c22858fd6a446d93e15

Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.

Unaffected versions might change over time as fixes are backported to
older supported kernel versions.  The official CVE entry at
	https://cve.org/CVERecord/?id=CVE-2026-97619
will be updated if fixes are backported, please check that for the most
up to date information about this issue.


Affected files
==============

The file(s) affected by this issue are:
	io_uring/rw.c


Mitigation
==========

The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes.  Individual
changes are never tested alone, but rather are part of a larger kernel
release.  Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all.  If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
	https://git.kernel.org/stable/c/cc580cee4dfa2ec9099c30ecbd4d804cbb996432
	https://git.kernel.org/stable/c/055d43a1233edbd80e558889258105ce63051bcd
	https://git.kernel.org/stable/c/796aa0547557e63338657ed1c487906f9fac4c73