Re: [PATCH v4 4/9] cxl/mem: Add basic IOCTL interface
On Mon, Feb 15, 2021 at 05:45:33PM -0800, Ben Widawsky wrote:
+ if (cmd->info.size_in) {
+ mbox_cmd.payload_in = kvzalloc(cmd->info.size_in, GFP_KERNEL);
+ if (!mbox_cmd.payload_in) {
+ rc = -ENOMEM;
+ goto out;
+ }
+
+ if (copy_from_user(mbox_cmd.payload_in,
+ u64_to_user_ptr(in_payload),
+ cmd->info.size_in)) {
+ rc = -EFAULT;
+ goto out;
+ }
Umm... Do you need to open-code vmemdup_user()? The only difference is
GFP_KERNEL allocation instead of GFP_USER one, and the latter is arguably
saner here... Zeroing is definitely pointless - you either overwrite
the entire buffer with copy_from_user(), or you fail and free the damn
thing.