Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S966448AbcCPIgS (ORCPT ); Wed, 16 Mar 2016 04:36:18 -0400 Received: from mail.kernel.org ([198.145.29.136]:59610 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965601AbcCPIJL (ORCPT ); Wed, 16 Mar 2016 04:09:11 -0400 From: lizf@kernel.org To: stable@vger.kernel.org Cc: linux-kernel@vger.kernel.org, AMAN DEEP , Mathias Nyman , Greg Kroah-Hartman , Zefan Li Subject: [PATCH 3.4 037/107] usb: xhci: Bugfix for NULL pointer deference in xhci_endpoint_init() function Date: Wed, 16 Mar 2016 16:05:31 +0800 Message-Id: <1458115601-5762-37-git-send-email-lizf@kernel.org> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1458115541-5712-1-git-send-email-lizf@kernel.org> References: <1458115541-5712-1-git-send-email-lizf@kernel.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2311 Lines: 61 From: AMAN DEEP 3.4.111-rc1 review patch. If anyone has any objections, please let me know. ------------------ commit 3496810663922617d4b706ef2780c279252ddd6a upstream. virt_dev->num_cached_rings counts on freed ring and is not updated correctly. In xhci_free_or_cache_endpoint_ring() function, the free ring is added into cache and then num_rings_cache is incremented as below: virt_dev->ring_cache[rings_cached] = virt_dev->eps[ep_index].ring; virt_dev->num_rings_cached++; here, free ring pointer is added to a current index and then index is incremented. So current index always points to empty location in the ring cache. For getting available free ring, current index should be decremented first and then corresponding ring buffer value should be taken from ring cache. But In function xhci_endpoint_init(), the num_rings_cached index is accessed before decrement. virt_dev->eps[ep_index].new_ring = virt_dev->ring_cache[virt_dev->num_rings_cached]; virt_dev->ring_cache[virt_dev->num_rings_cached] = NULL; virt_dev->num_rings_cached--; This is bug in manipulating the index of ring cache. And it should be as below: virt_dev->num_rings_cached--; virt_dev->eps[ep_index].new_ring = virt_dev->ring_cache[virt_dev->num_rings_cached]; virt_dev->ring_cache[virt_dev->num_rings_cached] = NULL; Signed-off-by: Aman Deep Signed-off-by: Mathias Nyman Signed-off-by: Greg Kroah-Hartman Signed-off-by: Zefan Li --- drivers/usb/host/xhci-mem.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/usb/host/xhci-mem.c b/drivers/usb/host/xhci-mem.c index aa38b1f..048cc38 100644 --- a/drivers/usb/host/xhci-mem.c +++ b/drivers/usb/host/xhci-mem.c @@ -1420,10 +1420,10 @@ int xhci_endpoint_init(struct xhci_hcd *xhci, /* Attempt to use the ring cache */ if (virt_dev->num_rings_cached == 0) return -ENOMEM; + virt_dev->num_rings_cached--; virt_dev->eps[ep_index].new_ring = virt_dev->ring_cache[virt_dev->num_rings_cached]; virt_dev->ring_cache[virt_dev->num_rings_cached] = NULL; - virt_dev->num_rings_cached--; xhci_reinit_cached_ring(xhci, virt_dev->eps[ep_index].new_ring, 1, type); } -- 1.9.1