From 1a3389ffc538a3a7b73335e84f33120a2f636f55 Mon Sep 17 00:00:00 2001 From: Catalin Marinas Date: Thu, 25 May 2017 17:26:47 +0100 Subject: [PATCH] drivers: dma-mapping: Do not leave an invalid area->pages pointer in dma_common_contiguous_remap() 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: Greg Kroah-Hartman Reported-by: Andrzej Hajda Acked-by: Laura Abbott Reviewed-by: Robin Murphy Signed-off-by: Catalin Marinas Signed-off-by: Greg Kroah-Hartman --- drivers/base/dma-mapping.c | 33 ++++++++++++++++++++++++--------- 1 file changed, 24 insertions(+), 9 deletions(-) diff --git a/drivers/base/dma-mapping.c b/drivers/base/dma-mapping.c index f3deb6af42ad..9dbef4d1baa4 100644 --- a/drivers/base/dma-mapping.c +++ b/drivers/base/dma-mapping.c @@ -275,6 +275,24 @@ int dma_common_mmap(struct device *dev, struct vm_area_struct *vma, EXPORT_SYMBOL(dma_common_mmap); #ifdef CONFIG_MMU +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; + + area = get_vm_area_caller(size, vm_flags, caller); + if (!area) + return NULL; + + if (map_vm_area(area, prot, pages)) { + vunmap(area->addr); + return NULL; + } + + return area; +} + /* * remaps an array of PAGE_SIZE pages into another vm_area * Cannot be used in non-sleeping contexts @@ -285,17 +303,12 @@ void *dma_common_pages_remap(struct page **pages, size_t size, { struct vm_struct *area; - area = get_vm_area_caller(size, vm_flags, caller); + area = __dma_common_pages_remap(pages, size, vm_flags, prot, caller); if (!area) return NULL; area->pages = pages; - if (map_vm_area(area, prot, pages)) { - vunmap(area->addr); - return NULL; - } - return area->addr; } @@ -310,7 +323,7 @@ void *dma_common_contiguous_remap(struct page *page, size_t size, { int i; struct page **pages; - void *ptr; + struct vm_struct *area; pages = kmalloc(sizeof(struct page *) << get_order(size), GFP_KERNEL); if (!pages) @@ -319,11 +332,13 @@ void *dma_common_contiguous_remap(struct page *page, size_t size, for (i = 0; i < (size >> PAGE_SHIFT); i++) pages[i] = nth_page(page, 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; } /* -- 2.20.1