From a4bc41504690b7d7064931909874f5b98cd148b6 Mon Sep 17 00:00:00 2001 From: Philipp Weber Date: Tue, 19 May 2026 15:00:14 +0200 Subject: [PATCH] HID: core: quiesce input in hid_hw_stop() to prevent use-after-free A driver's probe calls hid_device_io_start() to enable input delivery, then fails at a later initialization step and unwinds via hid_hw_stop(). The unwind frees struct hidraw via hidraw_disconnect() while in-flight HID reports may still be running on another CPU, dereferencing the freed object through hidraw_report_event(). syzbot reports the resulting use-after-free for the corsair-psu HID driver. Edward Adam Davis posted a per-driver fix for corsair-psu that adds an explicit hid_device_io_stop() before hid_hw_stop() in the probe error path ("hwmon: prevent packets from going to driver for probe", 2026-04-28). Auditing the tree shows 15 drivers call hid_device_io_start(); 7 also call hid_device_io_stop() and 8 do not: drivers calling hid_device_io_start() without a matching hid_device_io_stop() before hid_hw_stop(): drivers/hwmon/corsair-psu.c (fix posted by Edward) drivers/hwmon/corsair-cpro.c drivers/hwmon/nzxt-kraken3.c drivers/hwmon/nzxt-smart2.c drivers/hwmon/gigabyte_waterforce.c drivers/hid/hid-logitech-dj.c drivers/hid/hid-nintendo.c drivers/hid/hid-mcp2221.c Roughly half of all callers of the API are exposed. Centralize the quiesce in hid_hw_stop() so callers do not have to remember the matching stop: if a driver has left hdev->io_started true on entry, call hid_device_io_stop() before hid_disconnect(). For the 7 drivers that already call hid_device_io_stop() correctly, hdev->io_started is false on entry, the guard short-circuits, and behavior is unchanged. No Fixes: tag because the affected drivers gained their hid_device_io_start() calls independently over years; the bug is a class-wide API misuse rather than a regression from one commit. Reported-by: syzbot+9eebf5f6544c5e873858@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=9eebf5f6544c5e873858 Signed-off-by: Philipp Weber Signed-off-by: Jiri Kosina --- drivers/hid/hid-core.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/drivers/hid/hid-core.c b/drivers/hid/hid-core.c index 41a79e43c82b..6b024118d983 100644 --- a/drivers/hid/hid-core.c +++ b/drivers/hid/hid-core.c @@ -2440,9 +2440,16 @@ EXPORT_SYMBOL_GPL(hid_hw_start); * * This is usually called from remove function or from probe when something * failed and hid_hw_start was called already. + * + * If the caller enabled HID input via hid_device_io_start() and is unwinding + * without an explicit hid_device_io_stop(), quiesce input first so that + * in-flight reports cannot reach handlers (e.g. hidraw_report_event) whose + * backing objects hid_disconnect() is about to free. */ void hid_hw_stop(struct hid_device *hdev) { + if (hdev->io_started) + hid_device_io_stop(hdev); hid_disconnect(hdev); hdev->ll_driver->stop(hdev); }