From 0ed08faded1da03eb3def61502b27f81aef2e615 Mon Sep 17 00:00:00 2001 From: Alan Stern Date: Wed, 22 Apr 2020 16:18:48 -0400 Subject: HID: usbhid: Fix race between usbhid_close() and usbhid_stop() The syzbot fuzzer discovered a bad race between in the usbhid driver between usbhid_stop() and usbhid_close(). In particular, usbhid_stop() does: usb_free_urb(usbhid->urbin); ... usbhid->urbin = NULL; /* don't mess up next start */ and usbhid_close() does: usb_kill_urb(usbhid->urbin); with no mutual exclusion. If the two routines happen to run concurrently so that usb_kill_urb() is called in between the usb_free_urb() and the NULL assignment, it will access the deallocated urb structure -- a use-after-free bug. This patch adds a mutex to the usbhid private structure and uses it to enforce mutual exclusion of the usbhid_start(), usbhid_stop(), usbhid_open() and usbhid_close() callbacks. Reported-and-tested-by: syzbot+7bf5a7b0f0a1f9446f4c@syzkaller.appspotmail.com Signed-off-by: Alan Stern CC: Signed-off-by: Jiri Kosina --- drivers/hid/usbhid/usbhid.h | 1 + 1 file changed, 1 insertion(+) (limited to 'drivers/hid/usbhid/usbhid.h') diff --git a/drivers/hid/usbhid/usbhid.h b/drivers/hid/usbhid/usbhid.h index 8620408bd7af..75fe85d3d27a 100644 --- a/drivers/hid/usbhid/usbhid.h +++ b/drivers/hid/usbhid/usbhid.h @@ -80,6 +80,7 @@ struct usbhid_device { dma_addr_t outbuf_dma; /* Output buffer dma */ unsigned long last_out; /* record of last output for timeouts */ + struct mutex mutex; /* start/stop/open/close */ spinlock_t lock; /* fifo spinlock */ unsigned long iofl; /* I/O flags (CTRL_RUNNING, OUT_RUNNING) */ struct timer_list io_retry; /* Retry timer */ -- cgit v1.2.3