> +static ssize_t efivarfs_file_write(struct file *file,
> + const char __user *userbuf, size_t count, loff_t *ppos)
> +{
> + struct efivar_entry *var = file->private_data;
> + struct efivars *efivars;
> + efi_status_t status;
> + void *data;
> + u32 attributes;
> + struct inode *inode = file->f_mapping->host;
> + int datasize = count - sizeof(attributes);
long ?
> +
> + if (count < sizeof(attributes))
> + return -EINVAL;
> +
> + data = kmalloc(datasize, GFP_KERNEL);
This allows anyone who can open the file to allocate enormous amounts of
memory ... there should probably be a sanity check size here ?
> + if (!data)
> + return -ENOMEM;
> +
> + efivars = var->efivars;
> +
> + if (copy_from_user(&attributes, userbuf, sizeof(attributes))) {
> + count = -EFAULT;
Nope.. size_t is not necessarily signed. ssize_t is. This probably
happens to do the right thing but it's not really right.
> + switch (status) {
> + case EFI_SUCCESS:
Would it make sense for EFI to have a generic 'efi_to_errno' ?
> +static ssize_t efivarfs_file_read(struct file *file, char __user *userbuf,
> + size_t count, loff_t *ppos)
> +{
> + struct efivar_entry *var = file->private_data;
> + struct efivars *efivars = var->efivars;
> + efi_status_t status;
> + unsigned long datasize = 0;
> + u32 attributes;
> + void *data;
> + ssize_t size;
> +
> + status = efivars->ops->get_variable(var->var.VariableName,
> + &var->var.VendorGuid,
> + &attributes, &datasize, NULL);
> +
> + if (status != EFI_BUFFER_TOO_SMALL)
> + return 0;
This seems odd - the writer translates error codes this doesnt.
> +
> + data = kmalloc(datasize + 4, GFP_KERNEL);
Are you sure the firmware will never hand back insane datasize values ?
> +static const struct file_operations efivarfs_file_operations = {
> + .open = efivarfs_file_open,
> + .read = efivarfs_file_read,
> + .write = efivarfs_file_write,
> + .llseek = default_llseek,
But you don't implement llseek in your read/write methods ?
> + /* GUID plus trailing NULL */
> + name = kmalloc(len + 38, GFP_ATOMIC);
> +
> + for (i = 0; i < len; i++)
> + name[i] = entry->var.VariableName[i] & 0xFF;
Unchecked kmalloc - and an atomic one at that.
> + dentry = d_alloc_name(root, name);
...
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