linux-kernel - [PATCH 4.13 06/47] ANDROID: binder: add padding to binder_fd_array

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Date:   Fri,  8 Sep 2017 15:18:38 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Martijn Coenen <maco@...roid.com>
Subject: [PATCH 4.13 06/47] ANDROID: binder: add padding to binder_fd_array_object.

4.13-stable review patch.  If anyone has any objections, please let me know.

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

From: Martijn Coenen <maco@...roid.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@...roid.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.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;