binder: return errors from buffer copy functions

The buffer copy functions assumed the caller would ensure
correct alignment and that the memory to be copied was
completely within the binder buffer. There have been
a few cases discovered by syzkallar where a malformed
transaction created by a user could violated the
assumptions and resulted in a BUG_ON.

The fix is to remove the BUG_ON and always return the
error to be handled appropriately by the caller.

Acked-by: Martijn Coenen <maco@android.com>
Reported-by: syzbot+3ae18325f96190606754@syzkaller.appspotmail.com
Fixes: bde4a19fc04f ("binder: use userspace pointer as base of buffer space")
Suggested-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Todd Kjos <tkjos@google.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 11 insertions, 11 deletions

diff --git a/drivers/android/binder_alloc.h b/drivers/android/binder_alloc.h
index 71bfa95f8e09..db9c1b984695 100644
--- a/drivers/android/binder_alloc.h
+++ b/drivers/android/binder_alloc.h
@@ -159,17 +159,17 @@ binder_alloc_copy_user_to_buffer(struct binder_alloc *alloc,
 				 const void __user *from,
 				 size_t bytes);
 
-void binder_alloc_copy_to_buffer(struct binder_alloc *alloc,
-				 struct binder_buffer *buffer,
-				 binder_size_t buffer_offset,
-				 void *src,
-				 size_t bytes);
-
-void binder_alloc_copy_from_buffer(struct binder_alloc *alloc,
-				   void *dest,
-				   struct binder_buffer *buffer,
-				   binder_size_t buffer_offset,
-				   size_t bytes);
+int binder_alloc_copy_to_buffer(struct binder_alloc *alloc,
+				struct binder_buffer *buffer,
+				binder_size_t buffer_offset,
+				void *src,
+				size_t bytes);
+
+int binder_alloc_copy_from_buffer(struct binder_alloc *alloc,
+				  void *dest,
+				  struct binder_buffer *buffer,
+				  binder_size_t buffer_offset,
+				  size_t bytes);
 
 #endif /* _LINUX_BINDER_ALLOC_H */