From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-cve-announce@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@kernel.org>
Subject: CVE-2026-89673: nfsd: fix XDR padding calculation in ff_encode_getdeviceinfo
Date: Fri, 11 Sep 2026 21:46:02 +0200 [thread overview]
Message-ID: <2026091149-CVE-2026-89673-69d6@gregkh> (raw)
From: Greg Kroah-Hartman <gregkh@kernel.org>
Description
===========
In the Linux kernel, the following vulnerability has been resolved:
nfsd: fix XDR padding calculation in ff_encode_getdeviceinfo
nfsd4_ff_encode_getdeviceinfo() computes the da_addr_body reservation
as 16 + netid_len + addr_len, but the subsequent xdr_encode_opaque()
calls emit 8 + round_up(netid_len, 4) + round_up(addr_len, 4) bytes.
The mismatch means the declared da_addr_body length exceeds the actual
encoded data by 2-8 bytes on every flexfile GETDEVICEINFO reply,
leaking stale reply-page content to the client and mis-aligning the
subsequent version list decode.
Use xdr_align_size() for each string length to match what
xdr_encode_opaque() actually writes.
The Linux kernel CVE team has assigned CVE-2026-89673 to this issue.
Affected and fixed versions
===========================
Issue introduced in 6.4.16 with commit efcae97fa425ca6db9d126e37daccf2d7225cb09 and fixed in 6.12.109 with commit 74015b7be806ad9e21d46f7bd2831df280c6c783
Issue introduced in 6.4.16 with commit efcae97fa425ca6db9d126e37daccf2d7225cb09 and fixed in 6.18.50 with commit 41ebca28e17f84293650598f86bd69532ec1a8e0
Issue introduced in 6.4.16 with commit efcae97fa425ca6db9d126e37daccf2d7225cb09 and fixed in 7.2.4 with commit 62e5949f0dd5ec837af144860ff908369df4c7c9
Issue introduced in 6.4.16 with commit efcae97fa425ca6db9d126e37daccf2d7225cb09 and fixed in 7.3-rc1 with commit 8b989aaec85e1293a871d602590c951fe44b8647
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-2026-89673
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/nfsd/flexfilelayoutxdr.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/74015b7be806ad9e21d46f7bd2831df280c6c783
https://git.kernel.org/stable/c/41ebca28e17f84293650598f86bd69532ec1a8e0
https://git.kernel.org/stable/c/62e5949f0dd5ec837af144860ff908369df4c7c9
https://git.kernel.org/stable/c/8b989aaec85e1293a871d602590c951fe44b8647
reply other threads:[~2026-09-11 20:01 UTC|newest]
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