linux-kernel - [PATCH] usbhid: free raw_report buffers in usbhid

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Date:   Thu, 24 Jun 2021 00:10:29 +0530
From:   Anirudh Rayabharam <mail@...rudhrb.com>
To:     Jiri Kosina <jikos@...nel.org>,
        Benjamin Tissoires <benjamin.tissoires@...hat.com>
Cc:     gregkh@...uxfoundation.org,
        linux-kernel-mentees@...ts.linuxfoundation.org,
        Anirudh Rayabharam <mail@...rudhrb.com>,
        syzbot+47b26cd837ececfc666d@...kaller.appspotmail.com,
        linux-usb@...r.kernel.org, linux-input@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH] usbhid: free raw_report buffers in usbhid_stop

Free the unsent raw_report buffers when the device is removed.

Fixes a memory leak reported by syzbot at:
https://syzkaller.appspot.com/bug?id=7b4fa7cb1a7c2d3342a2a8a6c53371c8c418ab47

Reported-by: syzbot+47b26cd837ececfc666d@...kaller.appspotmail.com
Tested-by: syzbot+47b26cd837ececfc666d@...kaller.appspotmail.com
Signed-off-by: Anirudh Rayabharam <mail@...rudhrb.com>
---
 drivers/hid/usbhid/hid-core.c | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/drivers/hid/usbhid/hid-core.c b/drivers/hid/usbhid/hid-core.c
index 4e9077363c96..9c970e63670e 100644
--- a/drivers/hid/usbhid/hid-core.c
+++ b/drivers/hid/usbhid/hid-core.c
@@ -505,7 +505,7 @@ static void hid_ctrl(struct urb *urb)
 
 	if (unplug) {
 		usbhid->ctrltail = usbhid->ctrlhead;
-	} else {
+	} else if (usbhid->ctrlhead != usbhid->ctrltail) {
 		usbhid->ctrltail = (usbhid->ctrltail + 1) & (HID_CONTROL_FIFO_SIZE - 1);
 
 		if (usbhid->ctrlhead != usbhid->ctrltail &&
@@ -1223,9 +1223,20 @@ static void usbhid_stop(struct hid_device *hid)
 	mutex_lock(&usbhid->mutex);
 
 	clear_bit(HID_STARTED, &usbhid->iofl);
+
 	spin_lock_irq(&usbhid->lock);	/* Sync with error and led handlers */
 	set_bit(HID_DISCONNECTED, &usbhid->iofl);
+	while (usbhid->ctrltail != usbhid->ctrlhead) {
+		if (usbhid->ctrl[usbhid->ctrltail].dir == USB_DIR_OUT) {
+			kfree(usbhid->ctrl[usbhid->ctrltail].raw_report);
+			usbhid->ctrl[usbhid->ctrltail].raw_report = NULL;
+		}
+
+		usbhid->ctrltail = (usbhid->ctrltail + 1) &
+			(HID_CONTROL_FIFO_SIZE - 1);
+	}
 	spin_unlock_irq(&usbhid->lock);
+
 	usb_kill_urb(usbhid->urbin);
 	usb_kill_urb(usbhid->urbout);
 	usb_kill_urb(usbhid->urbctrl);
-- 
2.26.2