linux-cve-announce - CVE-2025-38176: binder: fix use-after-free in binderfs_evict

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Message-ID: <2025070402-CVE-2025-38176-c4b2@gregkh>
Date: Fri,  4 Jul 2025 12:40:03 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2025-38176: binder: fix use-after-free in binderfs_evict_inode()

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

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

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

binder: fix use-after-free in binderfs_evict_inode()

Running 'stress-ng --binderfs 16 --timeout 300' under KASAN-enabled
kernel, I've noticed the following:

BUG: KASAN: slab-use-after-free in binderfs_evict_inode+0x1de/0x2d0
Write of size 8 at addr ffff88807379bc08 by task stress-ng-binde/1699

CPU: 0 UID: 0 PID: 1699 Comm: stress-ng-binde Not tainted 6.14.0-rc7-g586de92313fc-dirty #13
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-3.fc41 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0x1c2/0x2a0
 ? __pfx_dump_stack_lvl+0x10/0x10
 ? __pfx__printk+0x10/0x10
 ? __pfx_lock_release+0x10/0x10
 ? __virt_addr_valid+0x18c/0x540
 ? __virt_addr_valid+0x469/0x540
 print_report+0x155/0x840
 ? __virt_addr_valid+0x18c/0x540
 ? __virt_addr_valid+0x469/0x540
 ? __phys_addr+0xba/0x170
 ? binderfs_evict_inode+0x1de/0x2d0
 kasan_report+0x147/0x180
 ? binderfs_evict_inode+0x1de/0x2d0
 binderfs_evict_inode+0x1de/0x2d0
 ? __pfx_binderfs_evict_inode+0x10/0x10
 evict+0x524/0x9f0
 ? __pfx_lock_release+0x10/0x10
 ? __pfx_evict+0x10/0x10
 ? do_raw_spin_unlock+0x4d/0x210
 ? _raw_spin_unlock+0x28/0x50
 ? iput+0x697/0x9b0
 __dentry_kill+0x209/0x660
 ? shrink_kill+0x8d/0x2c0
 shrink_kill+0xa9/0x2c0
 shrink_dentry_list+0x2e0/0x5e0
 shrink_dcache_parent+0xa2/0x2c0
 ? __pfx_shrink_dcache_parent+0x10/0x10
 ? __pfx_lock_release+0x10/0x10
 ? __pfx_do_raw_spin_lock+0x10/0x10
 do_one_tree+0x23/0xe0
 shrink_dcache_for_umount+0xa0/0x170
 generic_shutdown_super+0x67/0x390
 kill_litter_super+0x76/0xb0
 binderfs_kill_super+0x44/0x90
 deactivate_locked_super+0xb9/0x130
 cleanup_mnt+0x422/0x4c0
 ? lockdep_hardirqs_on+0x9d/0x150
 task_work_run+0x1d2/0x260
 ? __pfx_task_work_run+0x10/0x10
 resume_user_mode_work+0x52/0x60
 syscall_exit_to_user_mode+0x9a/0x120
 do_syscall_64+0x103/0x210
 ? asm_sysvec_apic_timer_interrupt+0x1a/0x20
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0xcac57b
Code: c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 f3 0f 1e fa 31 f6 e9 05 00 00 00 0f 1f 44 00 00 f3 0f 1e fa b8
RSP: 002b:00007ffecf4226a8 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6
RAX: 0000000000000000 RBX: 00007ffecf422720 RCX: 0000000000cac57b
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 00007ffecf422850
RBP: 00007ffecf422850 R08: 0000000028d06ab1 R09: 7fffffffffffffff
R10: 3fffffffffffffff R11: 0000000000000246 R12: 00007ffecf422718
R13: 00007ffecf422710 R14: 00007f478f87b658 R15: 00007ffecf422830
 </TASK>

Allocated by task 1705:
 kasan_save_track+0x3e/0x80
 __kasan_kmalloc+0x8f/0xa0
 __kmalloc_cache_noprof+0x213/0x3e0
 binderfs_binder_device_create+0x183/0xa80
 binder_ctl_ioctl+0x138/0x190
 __x64_sys_ioctl+0x120/0x1b0
 do_syscall_64+0xf6/0x210
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Freed by task 1705:
 kasan_save_track+0x3e/0x80
 kasan_save_free_info+0x46/0x50
 __kasan_slab_free+0x62/0x70
 kfree+0x194/0x440
 evict+0x524/0x9f0
 do_unlinkat+0x390/0x5b0
 __x64_sys_unlink+0x47/0x50
 do_syscall_64+0xf6/0x210
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

This 'stress-ng' workload causes the concurrent deletions from
'binder_devices' and so requires full-featured synchronization
to prevent list corruption.

I've found this issue independently but pretty sure that syzbot did
the same, so Reported-by: and Closes: should be applicable here as well.

The Linux kernel CVE team has assigned CVE-2025-38176 to this issue.


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

	Issue introduced in 6.14 with commit e77aff5528a183462714f750e45add6cc71e276a and fixed in 6.14.11 with commit 80ed8ab8efa0d18c03968a2321154f10e2d1a2e3
	Issue introduced in 6.14 with commit e77aff5528a183462714f750e45add6cc71e276a and fixed in 6.15.2 with commit aea61a1a77613d4184d7ebe7c1d7cb606458b43b
	Issue introduced in 6.14 with commit e77aff5528a183462714f750e45add6cc71e276a and fixed in 6.16-rc1 with commit 8c0a559825281764061a127632e5ad273f0466ad

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-2025-38176
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
	drivers/android/binder_internal.h
	drivers/android/binderfs.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/80ed8ab8efa0d18c03968a2321154f10e2d1a2e3
	https://git.kernel.org/stable/c/aea61a1a77613d4184d7ebe7c1d7cb606458b43b
	https://git.kernel.org/stable/c/8c0a559825281764061a127632e5ad273f0466ad