linux-cve-announce - CVE-2024-56555: binder: fix OOB in binder_add_freeze

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Message-ID: <2024122711-CVE-2024-56555-6abc@gregkh>
Date: Fri, 27 Dec 2024 15:23:06 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: CVE-2024-56555: binder: fix OOB in binder_add_freeze_work()

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

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

binder: fix OOB in binder_add_freeze_work()

In binder_add_freeze_work() we iterate over the proc->nodes with the
proc->inner_lock held. However, this lock is temporarily dropped to
acquire the node->lock first (lock nesting order). This can race with
binder_deferred_release() which removes the nodes from the proc->nodes
rbtree and adds them into binder_dead_nodes list. This leads to a broken
iteration in binder_add_freeze_work() as rb_next() will use data from
binder_dead_nodes, triggering an out-of-bounds access:

  ==================================================================
  BUG: KASAN: global-out-of-bounds in rb_next+0xfc/0x124
  Read of size 8 at addr ffffcb84285f7170 by task freeze/660

  CPU: 8 UID: 0 PID: 660 Comm: freeze Not tainted 6.11.0-07343-ga727812a8d45 #18
  Hardware name: linux,dummy-virt (DT)
  Call trace:
   rb_next+0xfc/0x124
   binder_add_freeze_work+0x344/0x534
   binder_ioctl+0x1e70/0x25ac
   __arm64_sys_ioctl+0x124/0x190

  The buggy address belongs to the variable:
   binder_dead_nodes+0x10/0x40
  [...]
  ==================================================================

This is possible because proc->nodes (rbtree) and binder_dead_nodes
(list) share entries in binder_node through a union:

	struct binder_node {
	[...]
		union {
			struct rb_node rb_node;
			struct hlist_node dead_node;
		};

Fix the race by checking that the proc is still alive. If not, simply
break out of the iteration.

The Linux kernel CVE team has assigned CVE-2024-56555 to this issue.


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

	Issue introduced in 6.12 with commit d579b04a52a183db47dfcb7a44304d7747d551e1 and fixed in 6.12.4 with commit 6b1be1da1f8279cf091266e71b5153c5b02aaff6
	Issue introduced in 6.12 with commit d579b04a52a183db47dfcb7a44304d7747d551e1 and fixed in 6.13-rc1 with commit 011e69a1b23011c0db3af4b8293fdd4522cc97b0

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-2024-56555
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/6b1be1da1f8279cf091266e71b5153c5b02aaff6
	https://git.kernel.org/stable/c/011e69a1b23011c0db3af4b8293fdd4522cc97b0