Ahead of the imminent Linux 6.19-rc5 release, the char/misc pull request was merged earlier today with a notable fix to the Rust Binder driver as well as adding the Intel Nova Lake Point S device ID to the MEI driver.

Today's char/misc merge brings a fix for the Rust Binder driver. Google's Rust Binder driver [1]debuted in the upstream Linux 6.18 kernel as an alternative to the existing C-based Binder driver in the kernel used by Android.

That Rust Binder driver led to [2]the first CVE being assigned to the kernel's Rust code . Now there is another fix to the Rust Binder driver due to a mishap when updating the Rust Binder driver for its Linux 6.18 mainlining.

Alice Ryhl of Google [3]explained in the patch last month:

"When forward-porting Rust Binder to 6.18, I neglected to take commit fb56fdf8b9a2 ("mm/list_lru: split the lock to per-cgroup scope") into account, and apparently I did not end up running the shrinker callback when I sanity tested the driver before submission. This leads to crashes like the following:

============================================

WARNING: possible recursive locking detected

6.18.0-mainline-maybe-dirty #1 Tainted: G IO

--------------------------------------------

kswapd0/68 is trying to acquire lock:

ffff956000fa18b0 (&l->lock){+.+.}-{2:2}, at: lock_list_lru_of_memcg+0x128/0x230

but task is already holding lock:

ffff956000fa18b0 (&l->lock){+.+.}-{2:2}, at: rust_helper_spin_lock+0xd/0x20

other info that might help us debug this:

Possible unsafe locking scenario:

CPU0

----

lock(&l->lock);

lock(&l->lock);

*** DEADLOCK ***

May be due to missing lock nesting notation

3 locks held by kswapd0/68:

#0: ffffffff90d2e260 (fs_reclaim){+.+.}-{0:0}, at: kswapd+0x597/0x1160

#1: ffff956000fa18b0 (&l->lock){+.+.}-{2:2}, at: rust_helper_spin_lock+0xd/0x20

#2: ffffffff90cf3680 (rcu_read_lock){....}-{1:2}, at: lock_list_lru_of_memcg+0x2d/0x230

To fix this, remove the spin_lock() call from rust_shrink_free_page()."

Dropping one (unsafe) line of Rust code avoids this crash. The patch is merged today for Linux 6.19-rc5 and is also marked for back-porting to the stable Linux 6.19 kernel.

The other notable bit with today's [4]char/misc pull is adding Nova Lake S support to the Intel Management Engine Interface "MEI" driver. As it's just a new device ID and no other driver changes needed, it's fine for this late-stage of the Linux 6.19 cycle as it doesn't risk regressing existing hardware support.



[1] https://www.phoronix.com/news/Rust-Binder-For-Linux-6.18

[2] https://www.phoronix.com/news/First-Linux-Rust-CVE

[3] https://lists.openwall.net/linux-kernel/2025/12/02/759

[4] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=9c7ef209cd0f7c1a92ed61eed3e835d6e4abc66c