blob: d74aefffed715e444c804243696b2dd47826c6ab [file] [log] [blame]
From e719ffa45164370554310ff2d99c7d9d471864ad Mon Sep 17 00:00:00 2001
From: "dan.carpenter@oracle.com" <dan.carpenter@oracle.com>
Date: Wed, 15 Jan 2020 20:46:28 +0300
Subject: [PATCH] HID: hiddev: Fix race in in hiddev_disconnect()
commit 5c02c447eaeda29d3da121a2e17b97ccaf579b51 upstream.
Syzbot reports that "hiddev" is used after it's free in hiddev_disconnect().
The hiddev_disconnect() function sets "hiddev->exist = 0;" so
hiddev_release() can free it as soon as we drop the "existancelock"
lock. This patch moves the mutex_unlock(&hiddev->existancelock) until
after we have finished using it.
Reported-by: syzbot+784ccb935f9900cc7c9e@syzkaller.appspotmail.com
Fixes: 7f77897ef2b6 ("HID: hiddev: fix potential use-after-free")
Suggested-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
diff --git a/drivers/hid/usbhid/hiddev.c b/drivers/hid/usbhid/hiddev.c
index 4aac11d8535a..86759ba04452 100644
--- a/drivers/hid/usbhid/hiddev.c
+++ b/drivers/hid/usbhid/hiddev.c
@@ -941,9 +941,9 @@ void hiddev_disconnect(struct hid_device *hid)
hiddev->exist = 0;
if (hiddev->open) {
- mutex_unlock(&hiddev->existancelock);
hid_hw_close(hiddev->hid);
wake_up_interruptible(&hiddev->wait);
+ mutex_unlock(&hiddev->existancelock);
} else {
mutex_unlock(&hiddev->existancelock);
kfree(hiddev);
--
2.7.4