CVE-2026-93054: uio: Fix stale info pointer in failed registration path

CVE-2026-93054: uio: Fix stale info pointer in failed registration path

[Greg Kroah-Hartman]

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

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

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

uio: Fix stale info pointer in failed registration path

After device_add(), the UIO device is visible to userspace and /dev/uioX
can be opened. If a later setup step fails, __uio_register_device()
unwinds the device but leaves idev->info pointing at the caller-owned
struct uio_info.

That is unsafe when an opener races with the failed registration path.
The open file keeps a reference to the uio_device, while the caller sees
registration failure and may free its struct uio_info. Later file
operations can then follow idev->info and dereference freed memory.

Handle post-device_add() failures like unregister: remove UIO attributes
while the info pointer is still valid, then clear idev->info under
info_lock and wake existing waiters/async users before removing the
device and minor. This makes already-open file descriptors observe the
same "device gone" state as normal uio_unregister_device().

The Linux kernel CVE team has assigned CVE-2026-93054 to this issue.


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

	Issue introduced in 4.18 with commit a93e7b331568227500186a465fee3c2cb5dffd1f and fixed in 5.10.270 with commit 63eaa7663335d482a8825c231213e312cacea567
	Issue introduced in 4.18 with commit a93e7b331568227500186a465fee3c2cb5dffd1f and fixed in 5.15.221 with commit df4faf65194ec6c315a59be4c6749eaeb3009243
	Issue introduced in 4.18 with commit a93e7b331568227500186a465fee3c2cb5dffd1f and fixed in 6.1.188 with commit 506b43dde5f9ac0068b1360e6b5dbee07fda59fb
	Issue introduced in 4.18 with commit a93e7b331568227500186a465fee3c2cb5dffd1f and fixed in 6.6.157 with commit 15340b00e665af805523b08515294a1aa1778151
	Issue introduced in 4.18 with commit a93e7b331568227500186a465fee3c2cb5dffd1f and fixed in 6.12.110 with commit 234156f6c6d9ec35dc47abbcc3adc3c79fc6a5ac
	Issue introduced in 4.18 with commit a93e7b331568227500186a465fee3c2cb5dffd1f and fixed in 6.18.52 with commit 16695e9059d80ea6661e8399064b0c01f641dd8c
	Issue introduced in 4.18 with commit a93e7b331568227500186a465fee3c2cb5dffd1f and fixed in 7.2.6 with commit ec5bd6731183eb6f619140c9bef2ee11ed818c20
	Issue introduced in 4.18 with commit a93e7b331568227500186a465fee3c2cb5dffd1f and fixed in 7.3-rc1 with commit 67b6fc084b034a91c3ec7907a3fed89a2450f30b
	Issue introduced in 4.14.100 with commit 085d735c858934e5d5bfaedb1fc98bd9135e6ff1

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-2026-93054
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/uio/uio.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/63eaa7663335d482a8825c231213e312cacea567
	https://git.kernel.org/stable/c/df4faf65194ec6c315a59be4c6749eaeb3009243
	https://git.kernel.org/stable/c/506b43dde5f9ac0068b1360e6b5dbee07fda59fb
	https://git.kernel.org/stable/c/15340b00e665af805523b08515294a1aa1778151
	https://git.kernel.org/stable/c/234156f6c6d9ec35dc47abbcc3adc3c79fc6a5ac
	https://git.kernel.org/stable/c/16695e9059d80ea6661e8399064b0c01f641dd8c
	https://git.kernel.org/stable/c/ec5bd6731183eb6f619140c9bef2ee11ed818c20
	https://git.kernel.org/stable/c/67b6fc084b034a91c3ec7907a3fed89a2450f30b