[PATCH 4.12 06/43] ANDROID: binder: add padding to binder_fd_array_object.

Greg Kroah-Hartman
2017-09-08T13:22:37Z

From: Martijn Coenen <maco@android.com>

commit 5cdcf4c6a638591ec0e98c57404a19e7f9997567 upstream.

binder_fd_array_object starts with a 4-byte header,
followed by a few fields that are 8 bytes when
ANDROID_BINDER_IPC_32BIT=N.

This can cause alignment issues in a 64-bit kernel
with a 32-bit userspace, as on x86_32 an 8-byte primitive
may be aligned to a 4-byte address. Pad with a __u32
to fix this.

Signed-off-by: Martijn Coenen <maco@android.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
include/uapi/linux/android/binder.h | 2 ++
1 file changed, 2 insertions(+)

--- a/include/uapi/linux/android/binder.h
+++ b/include/uapi/linux/android/binder.h
@@ -132,6 +132,7 @@ enum {

/* struct binder_fd_array_object - object describing an array of fds in a buffer
* @hdr: common header structure
+ * @pad: padding to ensure correct alignment
* @num_fds: number of file descriptors in the buffer
* @parent: index in offset array to buffer holding the fd array
* @parent_offset: start offset of fd array in the buffer
@@ -152,6 +153,7 @@ enum {
*/
struct binder_fd_array_object {
struct binder_object_header hdr;
+ __u32 pad;
binder_size_t num_fds;
binder_size_t parent;
binder_size_t parent_offset;