android: binder: Move buffer out of area shared with user space

Binder driver allocates buffer meta data in a region that is mapped
in user space. These meta data contain pointers in the kernel.

This patch allocates buffer meta data on the kernel heap that is
not mapped in user space, and uses a pointer to refer to the data mapped.

Signed-off-by: Sherry Yang <sherryy@android.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 5 insertions, 6 deletions

diff --git a/drivers/android/binder_alloc_selftest.c b/drivers/android/binder_alloc_selftest.c
index cc00ab6ee29d..0bf72079a9da 100644
--- a/drivers/android/binder_alloc_selftest.c
+++ b/drivers/android/binder_alloc_selftest.c
@@ -105,8 +105,9 @@ static bool check_buffer_pages_allocated(struct binder_alloc *alloc,
 	void *page_addr, *end;
 	int page_index;
 
-	end = (void *)PAGE_ALIGN((uintptr_t)buffer + size);
-	for (page_addr = buffer; page_addr < end; page_addr += PAGE_SIZE) {
+	end = (void *)PAGE_ALIGN((uintptr_t)buffer->data + size);
+	page_addr = buffer->data;
+	for (; page_addr < end; page_addr += PAGE_SIZE) {
 		page_index = (page_addr - alloc->buffer) / PAGE_SIZE;
 		if (!alloc->pages[page_index]) {
 			pr_err("incorrect alloc state at page index %d\n",
@@ -209,8 +210,7 @@ static void binder_selftest_alloc_size(struct binder_alloc *alloc,
 	 * Only BUFFER_NUM - 1 buffer sizes are adjustable since
 	 * we need one giant buffer before getting to the last page.
 	 */
-	back_sizes[0] += alloc->buffer_size - end_offset[BUFFER_NUM - 1]
-		- sizeof(struct binder_buffer) * BUFFER_NUM;
+	back_sizes[0] += alloc->buffer_size - end_offset[BUFFER_NUM - 1];
 	binder_selftest_free_seq(alloc, front_sizes, seq, 0);
 	binder_selftest_free_seq(alloc, back_sizes, seq, 0);
 }
@@ -228,8 +228,7 @@ static void binder_selftest_alloc_offset(struct binder_alloc *alloc,
 	prev = index == 0 ? 0 : end_offset[index - 1];
 	end = prev;
 
-	BUILD_BUG_ON((BUFFER_MIN_SIZE + sizeof(struct binder_buffer))
-		     * BUFFER_NUM >= PAGE_SIZE);
+	BUILD_BUG_ON(BUFFER_MIN_SIZE * BUFFER_NUM >= PAGE_SIZE);
 
 	for (align = SAME_PAGE_UNALIGNED; align < LOOP_END; align++) {
 		if (align % 2)