misc: fastrpc: Use memdup_user()

Switching to memdup_user() overwrites the allocated memory only once,
whereas kzalloc() followed by copy_from_user() initializes the allocated
memory to zero and then immediately overwrites it.

Fixes the following Coccinelle/coccicheck warning reported by
memdup_user.cocci:

	WARNING opportunity for memdup_user

Signed-off-by: Thorsten Blum <thorsten.blum@toblux.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Link: https://lore.kernel.org/r/20240705075900.424100-2-srinivas.kandagatla@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Author: toblux

drivers/misc/fastrpc.c

@@ -1259,17 +1259,12 @@ static int fastrpc_init_create_static_process(struct fastrpc_user *fl,
 		goto err;
 	}
 
-	name = kzalloc(init.namelen, GFP_KERNEL);
-	if (!name) {
-		err = -ENOMEM;
+	name = memdup_user(u64_to_user_ptr(init.name), init.namelen);
+	if (IS_ERR(name)) {
+		err = PTR_ERR(name);
 		goto err;
 	}
 
-	if (copy_from_user(name, (void __user *)(uintptr_t)init.name, init.namelen)) {
-		err = -EFAULT;
-		goto err_name;
-	}
-
 	if (!fl->cctx->remote_heap) {
 		err = fastrpc_remote_heap_alloc(fl, fl->sctx->dev, init.memlen,
 						&fl->cctx->remote_heap);