staging: android: binder: fix alignment issues
authorSerban Constantinescu <serban.constantinescu@arm.com>
Thu, 4 Jul 2013 09:54:46 +0000 (10:54 +0100)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Tue, 23 Jul 2013 21:37:22 +0000 (14:37 -0700)
The Android userspace aligns the data written to the binder buffers to
4bytes. Thus for 32bit platforms or 64bit platforms running an 32bit
Android userspace we can have a buffer looking like this:

platform    buffer(binder_cmd   pointer)      size
32/32                 32b         32b          8B
64/32                 32b         64b          12B
64/64                 32b         64b          12B

Thus the kernel needs to check that the buffer size is aligned to 4bytes
not to (void *) that will be 8bytes on 64bit machines.

The change does not affect existing 32bit ABI.

Signed-off-by: Serban Constantinescu <serban.constantinescu@arm.com>
Acked-by: Arve Hjønnevåg <arve@android.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
drivers/staging/android/binder.c

index 787fc921b1e7c88fa5376fc4b3ef87cd46e28e76..c6813ea15f403818fe96c28fede36ce385811dda 100644 (file)
@@ -1248,7 +1248,7 @@ static void binder_transaction_buffer_release(struct binder_proc *proc,
                struct flat_binder_object *fp;
                if (*offp > buffer->data_size - sizeof(*fp) ||
                    buffer->data_size < sizeof(*fp) ||
-                   !IS_ALIGNED(*offp, sizeof(void *))) {
+                   !IS_ALIGNED(*offp, sizeof(u32))) {
                        pr_err("transaction release %d bad offset %zd, size %zd\n",
                         debug_id, *offp, buffer->data_size);
                        continue;
@@ -1497,7 +1497,7 @@ static void binder_transaction(struct binder_proc *proc,
                struct flat_binder_object *fp;
                if (*offp > t->buffer->data_size - sizeof(*fp) ||
                    t->buffer->data_size < sizeof(*fp) ||
-                   !IS_ALIGNED(*offp, sizeof(void *))) {
+                   !IS_ALIGNED(*offp, sizeof(u32))) {
                        binder_user_error("%d:%d got transaction with invalid offset, %zd\n",
                                        proc->pid, thread->pid, *offp);
                        return_error = BR_FAILED_REPLY;