Messages in this thread Patch in this message | | | From | Sasha Levin <> | Subject | [PATCH AUTOSEL 4.14 05/19] HID: hiddev: Fix race in in hiddev_disconnect() | Date | Thu, 5 Mar 2020 12:15:26 -0500 |
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From: "dan.carpenter@oracle.com" <dan.carpenter@oracle.com>
[ Upstream commit 5c02c447eaeda29d3da121a2e17b97ccaf579b51 ]
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: Sasha Levin <sashal@kernel.org> --- drivers/hid/usbhid/hiddev.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/hid/usbhid/hiddev.c b/drivers/hid/usbhid/hiddev.c index bccd97cdc53f9..d9602f3a359e1 100644 --- a/drivers/hid/usbhid/hiddev.c +++ b/drivers/hid/usbhid/hiddev.c @@ -954,9 +954,9 @@ 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); -- 2.20.1
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