On Sat, 2012-11-03 at 00:21 +0000, Matthew Garrett wrote:
> Yeah. It's fair that this should be limited to whatever
> QueryVariableInfo() returns on systems that have that, and say 64K on
> older systems.
Folks how about something like this (compile-tested only)?
---
diff --git a/drivers/firmware/efivars.c b/drivers/firmware/efivars.c
index 9ac9340..b75fdf2 100644
--- a/drivers/firmware/efivars.c
+++ b/drivers/firmware/efivars.c
@@ -694,28 +694,54 @@ static ssize_t efivarfs_file_write(struct file *file,
struct inode *inode = file->f_mapping->host;
unsigned long datasize = count - sizeof(attributes);
unsigned long newdatasize;
+ u64 storage_size, remaining_size, max_size;
ssize_t bytes = 0;
if (count < sizeof(attributes))
return -EINVAL;
- data = kmalloc(datasize, GFP_KERNEL);
+ if (copy_from_user(&attributes, userbuf, sizeof(attributes)))
+ return -EFAULT;
- if (!data)
- return -ENOMEM;
+ if (attributes & ~(EFI_VARIABLE_MASK))
+ return -EINVAL;
efivars = var->efivars;
- if (copy_from_user(&attributes, userbuf, sizeof(attributes))) {
- bytes = -EFAULT;
- goto out;
+ /*
+ * Ensure that the user can't allocate arbitrarily large
+ * amounts of memory. Pick a default size of 64K if
+ * QueryVariableInfo() isn't supported by the firmware.
+ */
+ spin_lock(&efivars->lock);
+
+ if (!efivars->ops->query_variable_info)
+ status = EFI_UNSUPPORTED;
+ else {
+ const struct efivar_operations *fops = efivars->ops;
+ status = fops->query_variable_info(attributes, &storage_size,
+ &remaining_size, &max_size);
}
- if (attributes & ~(EFI_VARIABLE_MASK)) {
- bytes = -EINVAL;
- goto out;
+ spin_unlock(&efivars->lock);
+
+ if (status != EFI_SUCCESS) {
+ if (status != EFI_UNSUPPORTED)
+ return efi_status_to_err(status);
+
+ remaining_size = 65536;
+ }
+
+ if (datasize > remaining_size) {
+ printk(KERN_ERR "efivars: Variable size too big\n");
+ return -ENOSPC;
}
+ data = kmalloc(datasize, GFP_KERNEL);
+
+ if (!data)
+ return -ENOMEM;
+
if (copy_from_user(data, userbuf + sizeof(attributes), datasize)) {
bytes = -EFAULT;
goto out;
@@ -1709,6 +1735,9 @@ efivars_init(void)
ops.get_variable = efi.get_variable;
ops.set_variable = efi.set_variable;
ops.get_next_variable = efi.get_next_variable;
+#ifdef CONFIG_X86
+ ops.query_variable_info = efi.query_variable_info;
+#endif
error = register_efivars(&__efivars, &ops, efi_kobj);
if (error)
goto err_put;
diff --git a/include/linux/efi.h b/include/linux/efi.h
index 5e2308d..f80079c 100644
--- a/include/linux/efi.h
+++ b/include/linux/efi.h
@@ -646,6 +646,7 @@ struct efivar_operations {
efi_get_variable_t *get_variable;
efi_get_next_variable_t *get_next_variable;
efi_set_variable_t *set_variable;
+ efi_query_variable_info_t *query_variable_info;
};
struct efivars {
--
Matt Fleming, Intel Open Source Technology Center
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