Input: psmouse - fix use-after-free during protocol disconnect

When a PS/2 mouse is disconnected or unbound, psmouse_disconnect() calls
the protocol disconnect handler (psmouse->disconnect()). During this time,
stray bytes arriving from the physical controller can still be passed to
psmouse_handle_byte(), which will invoke psmouse->protocol_handler().

This creates an asynchronous race condition with vendor disconnect handlers
(such as synaptics_disconnect()), which free vendor-specific private
structures (psmouse->private). If a byte arrives while the structures
are being freed, it leads to a use-after-free or NULL pointer
dereference in the protocol handler.

Fix this by explicitly setting psmouse->protocol_handler to NULL
safely wrapped in scoped_guard(serio_pause_rx, serio) immediately before
calling the vendor disconnect handler. We also add an unlikely check
in psmouse_handle_byte() to safely drop incoming bytes if the protocol
handler is NULL.

Assisted-by: Antigravity:gemini-3.5-flash
Link: https://patch.msgid.link/20260727050803.1269941-1-dmitry.torokhov@gmail.com
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

0 files changed, 0 insertions, 0 deletions