linux-cve-announce - CVE-2026-23050: pNFS: Fix a deadlock when returning a delegation during open()

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Message-ID: <2026020450-CVE-2026-23050-378c@gregkh>
Date: Wed,  4 Feb 2026 17:04:45 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2026-23050: pNFS: Fix a deadlock when returning a delegation during open()

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

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

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

pNFS: Fix a deadlock when returning a delegation during open()

Ben Coddington reports seeing a hang in the following stack trace:
  0 [ffffd0b50e1774e0] __schedule at ffffffff9ca05415
  1 [ffffd0b50e177548] schedule at ffffffff9ca05717
  2 [ffffd0b50e177558] bit_wait at ffffffff9ca061e1
  3 [ffffd0b50e177568] __wait_on_bit at ffffffff9ca05cfb
  4 [ffffd0b50e1775c8] out_of_line_wait_on_bit at ffffffff9ca05ea5
  5 [ffffd0b50e177618] pnfs_roc at ffffffffc154207b [nfsv4]
  6 [ffffd0b50e1776b8] _nfs4_proc_delegreturn at ffffffffc1506586 [nfsv4]
  7 [ffffd0b50e177788] nfs4_proc_delegreturn at ffffffffc1507480 [nfsv4]
  8 [ffffd0b50e1777f8] nfs_do_return_delegation at ffffffffc1523e41 [nfsv4]
  9 [ffffd0b50e177838] nfs_inode_set_delegation at ffffffffc1524a75 [nfsv4]
 10 [ffffd0b50e177888] nfs4_process_delegation at ffffffffc14f41dd [nfsv4]
 11 [ffffd0b50e1778a0] _nfs4_opendata_to_nfs4_state at ffffffffc1503edf [nfsv4]
 12 [ffffd0b50e1778c0] _nfs4_open_and_get_state at ffffffffc1504e56 [nfsv4]
 13 [ffffd0b50e177978] _nfs4_do_open at ffffffffc15051b8 [nfsv4]
 14 [ffffd0b50e1779f8] nfs4_do_open at ffffffffc150559c [nfsv4]
 15 [ffffd0b50e177a80] nfs4_atomic_open at ffffffffc15057fb [nfsv4]
 16 [ffffd0b50e177ad0] nfs4_file_open at ffffffffc15219be [nfsv4]
 17 [ffffd0b50e177b78] do_dentry_open at ffffffff9c09e6ea
 18 [ffffd0b50e177ba8] vfs_open at ffffffff9c0a082e
 19 [ffffd0b50e177bd0] dentry_open at ffffffff9c0a0935

The issue is that the delegreturn is being asked to wait for a layout
return that cannot complete because a state recovery was initiated. The
state recovery cannot complete until the open() finishes processing the
delegations it was given.

The solution is to propagate the existing flags that indicate a
non-blocking call to the function pnfs_roc(), so that it knows not to
wait in this situation.

The Linux kernel CVE team has assigned CVE-2026-23050 to this issue.


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

	Issue introduced in 4.10 with commit 29ade5db12930ec60133f6a02791f4b1a4af2943 and fixed in 6.12.67 with commit a316fd9d3065b753b03d802530004aea481512cc
	Issue introduced in 4.10 with commit 29ade5db12930ec60133f6a02791f4b1a4af2943 and fixed in 6.18.7 with commit d6c75aa9d607044d1e5c8498eff0259eed356c32
	Issue introduced in 4.10 with commit 29ade5db12930ec60133f6a02791f4b1a4af2943 and fixed in 6.19-rc6 with commit 857bf9056291a16785ae3be1d291026b2437fc48

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-2026-23050
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:
	fs/nfs/nfs4proc.c
	fs/nfs/pnfs.c
	fs/nfs/pnfs.h


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/a316fd9d3065b753b03d802530004aea481512cc
	https://git.kernel.org/stable/c/d6c75aa9d607044d1e5c8498eff0259eed356c32
	https://git.kernel.org/stable/c/857bf9056291a16785ae3be1d291026b2437fc48