binder: fix handling of misaligned binder object

Fixes crash found by syzbot:
kernel BUG at drivers/android/binder_alloc.c:LINE! (2)

Reported-and-tested-by: syzbot+55de1eb4975dec156d8f@syzkaller.appspotmail.com
Signed-off-by: Todd Kjos <tkjos@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/android/binder.c b/drivers/android/binder.c
index 2dba539eb792cebc57b9632946d4d397ae78e99d..8685882da64cdaf60dcbac09d9c61735905b5300 100644 (file)
--- a/drivers/android/binder.c
+++ b/drivers/android/binder.c
@@ -2057,7 +2057,7 @@ static size_t binder_get_object(struct binder_proc *proc,
        size_t object_size = 0;
 
        read_size = min_t(size_t, sizeof(*object), buffer->data_size - offset);
-       if (read_size < sizeof(*hdr))
+       if (read_size < sizeof(*hdr) || !IS_ALIGNED(offset, sizeof(u32)))
                return 0;
        binder_alloc_copy_from_buffer(&proc->alloc, object, buffer,
                                      offset, read_size);