binder: fix max_thread type inconsistency

commit 42316941335644a98335f209daafa4c122f28983 upstream.

The type defined for the BINDER_SET_MAX_THREADS ioctl was changed from
size_t to __u32 in order to avoid incompatibility issues between 32 and
64-bit kernels. However, the internal types used to copy from user and
store the value were never updated. Use u32 to fix the inconsistency.

Fixes: a9350fc859 ("staging: android: binder: fix BINDER_SET_MAX_THREADS declaration")
Reported-by: Arve Hjønnevåg <arve@android.com>
Cc: stable@vger.kernel.org
Signed-off-by: Carlos Llamas <cmllamas@google.com>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Link: https://lore.kernel.org/r/20240421173750.3117808-1-cmllamas@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/android/binder.c

@@ -5165,7 +5165,7 @@ static long binder_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 			goto err;
 		break;
 	case BINDER_SET_MAX_THREADS: {
-		int max_threads;
+		u32 max_threads;
 
 		if (copy_from_user(&max_threads, ubuf,
 				   sizeof(max_threads))) {

drivers/android/binder_internal.h

@@ -420,7 +420,7 @@ struct binder_proc {
 	struct list_head todo;
 	struct binder_stats stats;
 	struct list_head delivered_death;
-	int max_threads;
+	u32 max_threads;
 	int requested_threads;
 	int requested_threads_started;
 	int tmp_ref;