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binder: fix freeze UAF in binder_release_work()

When a binder reference is cleaned up, any freeze work queued in the
associated process should also be removed. Otherwise, the reference is
freed while its ref->freeze.work is still queued in proc->work leading
to a use-after-free issue as shown by the following KASAN report:

==================================================================
BUG: KASAN: slab-use-after-free in binder_release_work+0x398/0x3d0
Read of size 8 at addr ffff31600ee91488 by task kworker/5:1/211

CPU: 5 UID: 0 PID: 211 Comm: kworker/5:1 Not tainted 6.11.0-rc7-00382-gfc6c92196396 #22
Hardware name: linux,dummy-virt (DT)
Workqueue: events binder_deferred_func
Call trace:
binder_release_work+0x398/0x3d0
binder_deferred_func+0xb60/0x109c
process_one_work+0x51c/0xbd4
worker_thread+0x608/0xee8

Allocated by task 703:
__kmalloc_cache_noprof+0x130/0x280
binder_thread_write+0xdb4/0x42a0
binder_ioctl+0x18f0/0x25ac
__arm64_sys_ioctl+0x124/0x190
invoke_syscall+0x6c/0x254

Freed by task 211:
kfree+0xc4/0x230
binder_deferred_func+0xae8/0x109c
process_one_work+0x51c/0xbd4
worker_thread+0x608/0xee8
==================================================================

This commit fixes the issue by ensuring any queued freeze work is removed
when cleaning up a binder reference.

Fixes: d579b04a52a1 ("binder: frozen notification")
Cc: stable@vger.kernel.org
Acked-by: Todd Kjos <tkjos@android.com>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Signed-off-by: Carlos Llamas <cmllamas@google.com>
Link: https://lore.kernel.org/r/20240926233632.821189-4-cmllamas@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

authored by

Carlos Llamas and committed by
Greg Kroah-Hartman
7e20434c 011e69a1

+6
+6
drivers/android/binder.c
··· 1225 1225 binder_dequeue_work(ref->proc, &ref->death->work); 1226 1226 binder_stats_deleted(BINDER_STAT_DEATH); 1227 1227 } 1228 + 1229 + if (ref->freeze) { 1230 + binder_dequeue_work(ref->proc, &ref->freeze->work); 1231 + binder_stats_deleted(BINDER_STAT_FREEZE); 1232 + } 1233 + 1228 1234 binder_stats_deleted(BINDER_STAT_REF); 1229 1235 } 1230 1236