linux-cve-announce - CVE-2026-23184: binder: fix UAF in binder_netlink

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Message-ID: <2026021430-CVE-2026-23184-a1f1@gregkh>
Date: Sat, 14 Feb 2026 17:28:41 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2026-23184: binder: fix UAF in binder_netlink_report()

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

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

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

binder: fix UAF in binder_netlink_report()

Oneway transactions sent to frozen targets via binder_proc_transaction()
return a BR_TRANSACTION_PENDING_FROZEN error but they are still treated
as successful since the target is expected to thaw at some point. It is
then not safe to access 't' after BR_TRANSACTION_PENDING_FROZEN errors
as the transaction could have been consumed by the now thawed target.

This is the case for binder_netlink_report() which derreferences 't'
after a pending frozen error, as pointed out by the following KASAN
report:

  ==================================================================
  BUG: KASAN: slab-use-after-free in binder_netlink_report.isra.0+0x694/0x6c8
  Read of size 8 at addr ffff00000f98ba38 by task binder-util/522

  CPU: 4 UID: 0 PID: 522 Comm: binder-util Not tainted 6.19.0-rc6-00015-gc03e9c42ae8f #1 PREEMPT
  Hardware name: linux,dummy-virt (DT)
  Call trace:
   binder_netlink_report.isra.0+0x694/0x6c8
   binder_transaction+0x66e4/0x79b8
   binder_thread_write+0xab4/0x4440
   binder_ioctl+0x1fd4/0x2940
   [...]

  Allocated by task 522:
   __kmalloc_cache_noprof+0x17c/0x50c
   binder_transaction+0x584/0x79b8
   binder_thread_write+0xab4/0x4440
   binder_ioctl+0x1fd4/0x2940
   [...]

  Freed by task 488:
   kfree+0x1d0/0x420
   binder_free_transaction+0x150/0x234
   binder_thread_read+0x2d08/0x3ce4
   binder_ioctl+0x488/0x2940
   [...]
  ==================================================================

Instead, make a transaction copy so the data can be safely accessed by
binder_netlink_report() after a pending frozen error. While here, add a
comment about not using t->buffer in binder_netlink_report().

The Linux kernel CVE team has assigned CVE-2026-23184 to this issue.


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

	Issue introduced in 6.18 with commit 63740349eba78f242bcbf60d5244d7f2b2600853 and fixed in 6.18.10 with commit a6050dedb6f1cc23e518e3a132ab74a0aad6df90
	Issue introduced in 6.18 with commit 63740349eba78f242bcbf60d5244d7f2b2600853 and fixed in 6.19 with commit 5e8a3d01544282e50d887d76f30d1496a0a53562

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-2026-23184
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/android/binder.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/a6050dedb6f1cc23e518e3a132ab74a0aad6df90
	https://git.kernel.org/stable/c/5e8a3d01544282e50d887d76f30d1496a0a53562