[PATCH 3.16 02/16] mm: cma: fix incorrect type conversion for size during dma allocation

[Ben Hutchings]

3.16.64-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Rohit Vaswani <rvaswani@xxxxxxxxxxxxxx>

commit 67a2e213e7e937c41c52ab5bc46bf3f4de469f6e upstream.

This was found during userspace fuzzing test when a large size dma cma
allocation is made by driver(like ion) through userspace.

  show_stack+0x10/0x1c
  dump_stack+0x74/0xc8
  kasan_report_error+0x2b0/0x408
  kasan_report+0x34/0x40
  __asan_storeN+0x15c/0x168
  memset+0x20/0x44
  __dma_alloc_coherent+0x114/0x18c

Signed-off-by: Rohit Vaswani <rvaswani@xxxxxxxxxxxxxx>
Acked-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Cc: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
[bwh: Backported to 3.16: cma_alloc() does not exist so only
 dma_alloc_from_contiguous() needs to be changed]
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
--- a/drivers/base/dma-contiguous.c
+++ b/drivers/base/dma-contiguous.c
@@ -313,7 +313,7 @@ static void clear_cma_bitmap(struct cma
  * global one. Requires architecture specific dev_get_cma_area() helper
  * function.
  */
-struct page *dma_alloc_from_contiguous(struct device *dev, int count,
+struct page *dma_alloc_from_contiguous(struct device *dev, size_t count,
 				       unsigned int align)
 {
 	unsigned long mask, pfn, pageno, start = 0;
@@ -327,7 +327,7 @@ struct page *dma_alloc_from_contiguous(s
 	if (align > CONFIG_CMA_ALIGNMENT)
 		align = CONFIG_CMA_ALIGNMENT;
 
-	pr_debug("%s(cma %p, count %d, align %d)\n", __func__, (void *)cma,
+	pr_debug("%s(cma %p, count %zu, align %d)\n", __func__, (void *)cma,
 		 count, align);
 
 	if (!count)
--- a/include/linux/dma-contiguous.h
+++ b/include/linux/dma-contiguous.h
@@ -116,7 +116,7 @@ static inline int dma_declare_contiguous
 	return ret;
 }
 
-struct page *dma_alloc_from_contiguous(struct device *dev, int count,
+struct page *dma_alloc_from_contiguous(struct device *dev, size_t count,
 				       unsigned int order);
 bool dma_release_from_contiguous(struct device *dev, struct page *pages,
 				 int count);
@@ -151,7 +151,7 @@ int dma_declare_contiguous(struct device
 }
 
 static inline
-struct page *dma_alloc_from_contiguous(struct device *dev, int count,
+struct page *dma_alloc_from_contiguous(struct device *dev, size_t count,
 				       unsigned int order)
 {
 	return NULL;