Patch "staging: android: ion: Zero CMA allocated memory" has been added to the 4.15-stable tree

This is a note to let you know that I've just added the patch titled

staging: android: ion: Zero CMA allocated memory

to the 4.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
staging-android-ion-zero-cma-allocated-memory.patch
and it can be found in the queue-4.15 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Liam Mark <[email protected]>
Date: Fri, 26 Jan 2018 09:48:18 -0800
Subject: staging: android: ion: Zero CMA allocated memory

From: Liam Mark <[email protected]>

commit 6d79bd5bb6c79a9dba4842040c9adf39e7806330 upstream.

Since commit 204f672255c2 ("staging: android: ion: Use CMA APIs directly") the CMA API is now used directly and therefore the allocated memory is no longer automatically zeroed.

Explicitly zero CMA allocated memory to ensure that no data is exposed to userspace.

---
 drivers/staging/android/ion/ion_cma_heap.c |   17 +++++++++++++++++
 1 file changed, 17 insertions(+)

@@ -21,6 +21,7 @@
 #include <linux/err.h>
 #include <linux/cma.h>
 #include <linux/scatterlist.h>
+#include <linux/highmem.h>
 
 #include "ion.h"
 

@@ -51,6 +52,22 @@ static int ion_cma_allocate(struct ion_h
 	if (!pages)
 		return -ENOMEM;
 
+	if (PageHighMem(pages)) {
+		unsigned long nr_clear_pages = nr_pages;
+		struct page *page = pages;
+
+		while (nr_clear_pages > 0) {
+			void *vaddr = kmap_atomic(page);
+
+			memset(vaddr, 0, PAGE_SIZE);
+			kunmap_atomic(vaddr);
+			page++;
+			nr_clear_pages--;
+		}
+	} else {
+		memset(page_address(pages), 0, size);
+	}
+
 	table = kmalloc(sizeof(*table), GFP_KERNEL);
 	if (!table)
 		goto err;

Patches currently in stable-queue which might be from [email protected] are

queue-4.15/staging-android-ion-zero-cma-allocated-memory.patch