linux-kernel - Re: [PATCH v5] driver core: enforce device_lock for driver_match

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Message-Id: <DFNPG605THQ0.3S8WLUGKB5IP7@kernel.org>
Date: Tue, 13 Jan 2026 20:23:20 +0100
From: "Danilo Krummrich" <dakr@...nel.org>
To: "Gui-Dong Han" <hanguidong02@...il.com>
Cc: <gregkh@...uxfoundation.org>, <rafael@...nel.org>,
 <linux-kernel@...r.kernel.org>, <baijiaju1990@...il.com>, "Qiu-ji Chen"
 <chenqiuji666@...il.com>
Subject: Re: [PATCH v5] driver core: enforce device_lock for
 driver_match_device()

On Tue Jan 13, 2026 at 5:28 PM CET, Gui-Dong Han wrote:
> Currently, driver_match_device() is called from three sites. One site
> (__device_attach_driver) holds device_lock(dev), but the other two
> (bind_store and __driver_attach) do not. This inconsistency means that
> bus match() callbacks are not guaranteed to be called with the lock
> held.
>
> Fix this by introducing driver_match_device_locked(), which guarantees
> holding the device lock using a scoped guard. Replace the unlocked calls
> in bind_store() and __driver_attach() with this new helper. Also add a
> lock assertion to driver_match_device() to enforce this guarantee.
>
> This consistency also fixes a known race condition. The driver_override
> implementation relies on the device_lock, so the missing lock led to the
> use-after-free (UAF) reported in Bugzilla for buses using this field.
>
> Stress testing the two newly locked paths for 24 hours with
> CONFIG_PROVE_LOCKING and CONFIG_LOCKDEP enabled showed no UAF recurrence
> and no lockdep warnings.
>
> Closes: https://bugzilla.kernel.org/show_bug.cgi?id=220789

Fixes: 49b420a13ff9 ("driver core: check bus->match without holding device lock")

> Suggested-by: Qiu-ji Chen <chenqiuji666@...il.com>
> Signed-off-by: Gui-Dong Han <hanguidong02@...il.com>

This looks good now!

Reviewed-by: Danilo Krummrich <dakr@...nel.org>