Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759283Ab2FQSjL (ORCPT ); Sun, 17 Jun 2012 14:39:11 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:50186 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758033Ab2FQSWe (ORCPT ); Sun, 17 Jun 2012 14:22:34 -0400 Message-Id: <20120617175950.170141377@decadent.org.uk> User-Agent: quilt/0.60-1 Date: Sun, 17 Jun 2012 19:00:42 +0100 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, Takashi Iwai , Sarah Sharp , Oliver Neukum Subject: [ 61/69] xhci: Fix invalid loop check in xhci_free_tt_info() In-Reply-To: <20120617175941.281333656@decadent.org.uk> X-SA-Exim-Connect-IP: 2001:470:1f08:1539:21c:bfff:fe03:f805 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3044 Lines: 94 3.2-stable review patch. If anyone has any objections, please let me know. ------------------ From: Takashi Iwai commit 46ed8f00d8982e49f8fe2c1a9cea192f640cb3ba upstream. xhci_free_tt_info() may access the invalid memory when it removes the last entry but the list is not empty. Then tt_next reaches to the list head but it still tries to check the tt_info of that entry. This patch fixes the bug and cleans up the messy code by rewriting with a simple list_for_each_entry_safe(). This patch should be backported to kernels as old as 3.2, that contain the commit 839c817ce67178ca3c7c7ad534c571bba1e69ebe "xhci: Store information about roothubs and TTs." Signed-off-by: Takashi Iwai Signed-off-by: Sarah Sharp Reviewed-by: Oliver Neukum Signed-off-by: Ben Hutchings --- drivers/usb/host/xhci-mem.c | 39 ++++++++++----------------------------- 1 file changed, 10 insertions(+), 29 deletions(-) diff --git a/drivers/usb/host/xhci-mem.c b/drivers/usb/host/xhci-mem.c index ec4338e..898dfc8 100644 --- a/drivers/usb/host/xhci-mem.c +++ b/drivers/usb/host/xhci-mem.c @@ -793,10 +793,9 @@ static void xhci_free_tt_info(struct xhci_hcd *xhci, struct xhci_virt_device *virt_dev, int slot_id) { - struct list_head *tt; struct list_head *tt_list_head; - struct list_head *tt_next; - struct xhci_tt_bw_info *tt_info; + struct xhci_tt_bw_info *tt_info, *next; + bool slot_found = false; /* If the device never made it past the Set Address stage, * it may not have the real_port set correctly. @@ -808,34 +807,16 @@ static void xhci_free_tt_info(struct xhci_hcd *xhci, } tt_list_head = &(xhci->rh_bw[virt_dev->real_port - 1].tts); - if (list_empty(tt_list_head)) - return; - - list_for_each(tt, tt_list_head) { - tt_info = list_entry(tt, struct xhci_tt_bw_info, tt_list); - if (tt_info->slot_id == slot_id) + list_for_each_entry_safe(tt_info, next, tt_list_head, tt_list) { + /* Multi-TT hubs will have more than one entry */ + if (tt_info->slot_id == slot_id) { + slot_found = true; + list_del(&tt_info->tt_list); + kfree(tt_info); + } else if (slot_found) { break; + } } - /* Cautionary measure in case the hub was disconnected before we - * stored the TT information. - */ - if (tt_info->slot_id != slot_id) - return; - - tt_next = tt->next; - tt_info = list_entry(tt, struct xhci_tt_bw_info, - tt_list); - /* Multi-TT hubs will have more than one entry */ - do { - list_del(tt); - kfree(tt_info); - tt = tt_next; - if (list_empty(tt_list_head)) - break; - tt_next = tt->next; - tt_info = list_entry(tt, struct xhci_tt_bw_info, - tt_list); - } while (tt_info->slot_id == slot_id); } int xhci_alloc_tt_info(struct xhci_hcd *xhci, -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/