From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-cve-announce@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@kernel.org>
Subject: CVE-2026-64327: usb: gadget: f_fs: Initialize epfile->in early to fix endpoint direction checks
Date: Sat, 25 Jul 2026 10:49:04 +0200 [thread overview]
Message-ID: <2026072512-CVE-2026-64327-fb4d@gregkh> (raw)
From: Greg Kroah-Hartman <gregkh@kernel.org>
Description
===========
In the Linux kernel, the following vulnerability has been resolved:
usb: gadget: f_fs: Initialize epfile->in early to fix endpoint direction checks
When parsing endpoint descriptors, ffs_data_got_descs() generates the
eps_addrmap which contains the endpoint direction. However, epfile->in
was previously only populated in ffs_func_eps_enable() which executes
upon USB host connection. As a result, early userspace ioctls like
FUNCTIONFS_DMABUF_ATTACH that run before the host connects would see
epfile->in as 0, leading to incorrect DMA directions.
By moving the initialization to ffs_epfiles_create(), epfile->in is
accurate before userspace opens the endpoint files.
The Linux kernel CVE team has assigned CVE-2026-64327 to this issue.
Affected and fixed versions
===========================
Issue introduced in 6.9 with commit 7b07a2a7ca02a20124b552be96c5a56910795488 and fixed in 6.12.96 with commit 82cf1142e5ccf2b6d6d22ef713aaf3e5f2b5716b
Issue introduced in 6.9 with commit 7b07a2a7ca02a20124b552be96c5a56910795488 and fixed in 6.18.39 with commit 9e04055ab5fc0470a0031ee6934739f9aa8f34a5
Issue introduced in 6.9 with commit 7b07a2a7ca02a20124b552be96c5a56910795488 and fixed in 7.1.4 with commit f99f32ea9aa976afcbec20647ed33b50a52002c1
Issue introduced in 6.9 with commit 7b07a2a7ca02a20124b552be96c5a56910795488 and fixed in 7.2-rc3 with commit 82cfd4739011bdc7e87b5d585703427e89ddfaa5
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-2026-64327
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:
drivers/usb/gadget/function/f_fs.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/82cf1142e5ccf2b6d6d22ef713aaf3e5f2b5716b
https://git.kernel.org/stable/c/9e04055ab5fc0470a0031ee6934739f9aa8f34a5
https://git.kernel.org/stable/c/f99f32ea9aa976afcbec20647ed33b50a52002c1
https://git.kernel.org/stable/c/82cfd4739011bdc7e87b5d585703427e89ddfaa5
reply other threads:[~2026-07-25 8:53 UTC|newest]
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