Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1952629AbdDYSWu (ORCPT ); Tue, 25 Apr 2017 14:22:50 -0400 Received: from foss.arm.com ([217.140.101.70]:45790 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1952591AbdDYSWg (ORCPT ); Tue, 25 Apr 2017 14:22:36 -0400 From: Catalin Marinas To: linux-kernel@vger.kernel.org Cc: linux-arm-kernel@lists.infradead.org, geert@linux-m68k.org, a.hajda@samsung.com, robin.murphy@arm.com, Laura Abbott , Greg Kroah-Hartman Subject: [PATCH] arm64: Do not leave an invalid area->pages pointer in dma_common_contiguous_remap() Date: Tue, 25 Apr 2017 19:22:23 +0100 Message-Id: <1493144543-2497-1-git-send-email-catalin.marinas@arm.com> X-Mailer: git-send-email 2.1.4 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3128 Lines: 94 The dma_common_pages_remap() function allocates a vm_struct object and initialises the pages pointer to value passed as argument. However, when this function is called dma_common_contiguous_remap(), the pages array is only temporarily allocated, being freed shortly after dma_common_contiguous_remap() returns. Architecture code checking the validity of an area->pages pointer would incorrectly dereference already freed pointers. This has been exposed by the arm64 commit 44176bb38fa4 ("arm64: Add support for DMA_ATTR_FORCE_CONTIGUOUS to IOMMU"). Fixes: 513510ddba96 ("common: dma-mapping: introduce common remapping functions") Cc: Laura Abbott Cc: Greg Kroah-Hartman Reported-by: Andrzej Hajda Signed-off-by: Catalin Marinas --- This is for correctness since once the arm64's mmap and get_sgtable ops are fixed for DMA_ATTR_FORCE_CONTIGUOUS, we would no longer see the issue. Anyway, it's better to get this fixed in case others trip over a similar issue. I added a "Fixes" tag for completeness but I'm not sure it's worth back-porting. drivers/base/dma-mapping.c | 29 ++++++++++++++++++++++------- 1 file changed, 22 insertions(+), 7 deletions(-) diff --git a/drivers/base/dma-mapping.c b/drivers/base/dma-mapping.c index efd71cf4fdea..ab7071041141 100644 --- a/drivers/base/dma-mapping.c +++ b/drivers/base/dma-mapping.c @@ -277,8 +277,8 @@ EXPORT_SYMBOL(dma_common_mmap); * remaps an array of PAGE_SIZE pages into another vm_area * Cannot be used in non-sleeping contexts */ -void *dma_common_pages_remap(struct page **pages, size_t size, - unsigned long vm_flags, pgprot_t prot, +static struct vm_struct *__dma_common_pages_remap(struct page **pages, + size_t size, unsigned long vm_flags, pgprot_t prot, const void *caller) { struct vm_struct *area; @@ -287,13 +287,26 @@ void *dma_common_pages_remap(struct page **pages, size_t size, if (!area) return NULL; - area->pages = pages; - if (map_vm_area(area, prot, pages)) { vunmap(area->addr); return NULL; } + return area; +} + +void *dma_common_pages_remap(struct page **pages, size_t size, + unsigned long vm_flags, pgprot_t prot, + const void *caller) +{ + struct vm_struct *area; + + area = __dma_common_pages_remap(pages, size, vm_flags, prot, caller); + if (!area) + return NULL; + + area->pages = pages; + return area->addr; } @@ -308,7 +321,7 @@ void *dma_common_contiguous_remap(struct page *page, size_t size, { int i; struct page **pages; - void *ptr; + struct vm_struct *area; unsigned long pfn; pages = kmalloc(sizeof(struct page *) << get_order(size), GFP_KERNEL); @@ -318,11 +331,13 @@ void *dma_common_contiguous_remap(struct page *page, size_t size, for (i = 0, pfn = page_to_pfn(page); i < (size >> PAGE_SHIFT); i++) pages[i] = pfn_to_page(pfn + i); - ptr = dma_common_pages_remap(pages, size, vm_flags, prot, caller); + area = __dma_common_pages_remap(pages, size, vm_flags, prot, caller); kfree(pages); - return ptr; + if (!area) + return NULL; + return area->addr; } /*