From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759602Ab3LBVTo (ORCPT ); Mon, 2 Dec 2013 16:19:44 -0500 Received: from mail.linuxfoundation.org ([140.211.169.12]:38411 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753324Ab3LBTMs (ORCPT ); Mon, 2 Dec 2013 14:12:48 -0500 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Olav Haugan Subject: [PATCH 3.10 010/173] staging: zsmalloc: Ensure handle is never 0 on success Date: Mon, 2 Dec 2013 11:09:53 -0800 Message-Id: <20131202191144.100960023@linuxfoundation.org> X-Mailer: git-send-email 1.8.4.3.gca3854a In-Reply-To: <20131202191142.873808297@linuxfoundation.org> References: <20131202191142.873808297@linuxfoundation.org> User-Agent: quilt/0.60-8.1.3 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.10-stable review patch. If anyone has any objections, please let me know. ------------------ From: Olav Haugan commit 67296874eb1cc80317bf2a8fba22b494e21eb29b upstream. zsmalloc encodes a handle using the pfn and an object index. On hardware platforms with physical memory starting at 0x0 the pfn can be 0. This causes the encoded handle to be 0 and is incorrectly interpreted as an allocation failure. This issue affects all current and future SoCs with physical memory starting at 0x0. All MSM8974 SoCs which includes Google Nexus 5 devices are affected. To prevent this false error we ensure that the encoded handle will not be 0 when allocation succeeds. Signed-off-by: Olav Haugan Signed-off-by: Greg Kroah-Hartman --- drivers/staging/zsmalloc/zsmalloc-main.c | 17 +++++++++++++---- 1 file changed, 13 insertions(+), 4 deletions(-) --- a/drivers/staging/zsmalloc/zsmalloc-main.c +++ b/drivers/staging/zsmalloc/zsmalloc-main.c @@ -430,7 +430,12 @@ static struct page *get_next_page(struct return next; } -/* Encode as a single handle value */ +/* + * Encode as a single handle value. + * On hardware platforms with physical memory starting at 0x0 the pfn + * could be 0 so we ensure that the handle will never be 0 by adjusting the + * encoded obj_idx value before encoding. + */ static void *obj_location_to_handle(struct page *page, unsigned long obj_idx) { unsigned long handle; @@ -441,17 +446,21 @@ static void *obj_location_to_handle(stru } handle = page_to_pfn(page) << OBJ_INDEX_BITS; - handle |= (obj_idx & OBJ_INDEX_MASK); + handle |= ((obj_idx + 1) & OBJ_INDEX_MASK); return (void *)handle; } -/* Decode pair from the given object handle */ +/* + * Decode pair from the given object handle. We adjust the + * decoded obj_idx back to its original value since it was adjusted in + * obj_location_to_handle(). + */ static void obj_handle_to_location(unsigned long handle, struct page **page, unsigned long *obj_idx) { *page = pfn_to_page(handle >> OBJ_INDEX_BITS); - *obj_idx = handle & OBJ_INDEX_MASK; + *obj_idx = (handle & OBJ_INDEX_MASK) - 1; } static unsigned long obj_idx_to_offset(struct page *page,