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Message-ID: <CAD0t5oNFc0UtFpsPVWBVTzZbEgqy+PeuW4uv1_sNM=+Aqbu2kA@mail.gmail.com>
Date: Tue, 24 Sep 2024 17:52:47 -0700
From: Todd Kjos <tkjos@...roid.com>
To: Carlos Llamas <cmllamas@...gle.com>
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>, Arve Hjønnevåg <arve@...roid.com>,
Martijn Coenen <maco@...roid.com>, Joel Fernandes <joel@...lfernandes.org>,
Christian Brauner <brauner@...nel.org>, Suren Baghdasaryan <surenb@...gle.com>,
Yu-Ting Tseng <yutingtseng@...gle.com>, linux-kernel@...r.kernel.org,
kernel-team@...roid.com, Alice Ryhl <aliceryhl@...gle.com>, stable@...r.kernel.org
Subject: Re: [PATCH 3/4] binder: fix freeze UAF in binder_release_work()
On Tue, Sep 24, 2024 at 11:44 AM Carlos Llamas <cmllamas@...gle.com> wrote:
>
> 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@...r.kernel.org
> Signed-off-by: Carlos Llamas <cmllamas@...gle.com>
Acked-by: Todd Kjos <tkjos@...roid.com>
> ---
> drivers/android/binder.c | 6 ++++++
> 1 file changed, 6 insertions(+)
>
> diff --git a/drivers/android/binder.c b/drivers/android/binder.c
> index 8bca2de6fa24..d955135ee37a 100644
> --- a/drivers/android/binder.c
> +++ b/drivers/android/binder.c
> @@ -1225,6 +1225,12 @@ static void binder_cleanup_ref_olocked(struct binder_ref *ref)
> binder_dequeue_work(ref->proc, &ref->death->work);
> binder_stats_deleted(BINDER_STAT_DEATH);
> }
> +
> + if (ref->freeze) {
> + binder_dequeue_work(ref->proc, &ref->freeze->work);
> + binder_stats_deleted(BINDER_STAT_FREEZE);
> + }
> +
> binder_stats_deleted(BINDER_STAT_REF);
> }
>
> --
> 2.46.0.792.g87dc391469-goog
>
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