CVE-2026-90102: NFSv4/pnfs: key the data server cache on the NFS version

CVE-2026-90102: NFSv4/pnfs: key the data server cache on the NFS version

[Greg Kroah-Hartman]

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

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

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

NFSv4/pnfs: key the data server cache on the NFS version

nfs4_pnfs_ds_add() keys the per-net data server cache on the multipath
address set alone, and struct nfs4_pnfs_ds records no version. That
suffices for the files layout driver, which always connects with version
4, but flexfiles takes its version tuple from GETDEVICEINFO per device,
and one address can legitimately serve both NFSv3 and NFSv4.

Two deviceids on one address with different ds_versions[0].version
therefore share a single nfs4_pnfs_ds, and whichever mirror connects
first pins ds_clp to its own version. The other one is handed that
client anyway, so it selects rpc_call_ops for a version the connection
does not speak, and the mismatched sequence-slot handling dereferences
NULL.

Add the version to the cache key so the two cannot alias, giving each
version its own nfs4_pnfs_ds and connection while both mirrors stay
usable. Only the major version is compared, since that is what selects
rpc_call_ops and rpc_ops; v4.0 and v4.1 keep sharing a client. The files
layout driver passes the 4 it already hardcodes at connect time.

The Linux kernel CVE team has assigned CVE-2026-90102 to this issue.


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

	Issue introduced in 4.0 with commit d67ae825a59d639e4d8b82413af84d854617a87e and fixed in 5.10.270 with commit ffb100b0da0e217d5d63ce6fe092f9c29e59f7dd
	Issue introduced in 4.0 with commit d67ae825a59d639e4d8b82413af84d854617a87e and fixed in 5.15.221 with commit 02e160922bc83cd25e346a028ed43cbdb0b57e1a
	Issue introduced in 4.0 with commit d67ae825a59d639e4d8b82413af84d854617a87e and fixed in 6.1.188 with commit bc7aa9d8aff826031ffe25eba7f2f3acafcbf7a1
	Issue introduced in 4.0 with commit d67ae825a59d639e4d8b82413af84d854617a87e and fixed in 6.6.157 with commit dd5bd091daa48c6ed8f9235ddf448aa288a0881f
	Issue introduced in 4.0 with commit d67ae825a59d639e4d8b82413af84d854617a87e and fixed in 6.12.110 with commit f2994ba1263d9e88d3d9ae1d097c5cf811d4bfa5
	Issue introduced in 4.0 with commit d67ae825a59d639e4d8b82413af84d854617a87e and fixed in 6.18.52 with commit 27f640cd92eebf5c2f64336be7ca24f4636390cb
	Issue introduced in 4.0 with commit d67ae825a59d639e4d8b82413af84d854617a87e and fixed in 7.2.6 with commit bbc975cfb07a146843fde1126c43441e76177539
	Issue introduced in 4.0 with commit d67ae825a59d639e4d8b82413af84d854617a87e and fixed in 7.3-rc1 with commit 13c23c5cb977f66390795437fd3837887ce1fd75

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-2026-90102
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/filelayout/filelayoutdev.c
	fs/nfs/flexfilelayout/flexfilelayoutdev.c
	fs/nfs/pnfs.h
	fs/nfs/pnfs_nfs.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/ffb100b0da0e217d5d63ce6fe092f9c29e59f7dd
	https://git.kernel.org/stable/c/02e160922bc83cd25e346a028ed43cbdb0b57e1a
	https://git.kernel.org/stable/c/bc7aa9d8aff826031ffe25eba7f2f3acafcbf7a1
	https://git.kernel.org/stable/c/dd5bd091daa48c6ed8f9235ddf448aa288a0881f
	https://git.kernel.org/stable/c/f2994ba1263d9e88d3d9ae1d097c5cf811d4bfa5
	https://git.kernel.org/stable/c/27f640cd92eebf5c2f64336be7ca24f4636390cb
	https://git.kernel.org/stable/c/bbc975cfb07a146843fde1126c43441e76177539
	https://git.kernel.org/stable/c/13c23c5cb977f66390795437fd3837887ce1fd75