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[PATCH] Fix race in efi variable delete code

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Fix race when deleting an EFI variable and issuing another EFI command on
the same variable.  The removal of the variable from the efivars_list
should be done in efivar_delete and not delayed until the kobject release.

Furthermore, remove the item from the list at module unload time, and use
list_for_each_entry_safe() rather than list_for_each_safe() for
readability.

Tested on ia64.

Signed-off-by: Prarit Bhargava <prarit@redhat.com>
Signed-off-by: Matt Domsch <Matt_Domsch@dell.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Matt Domsch 2007-01-26 00:57:18 -08:00 committed by Linus Torvalds
parent 01f2073411
commit 496a0fc8c5
1 changed files with 12 additions and 17 deletions
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29
drivers/firmware/efivars.c
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@ -122,8 +122,6 @@ struct efivar_entry {
struct kobject kobj;
};
#define get_efivar_entry(n) list_entry(n, struct efivar_entry, list)
struct efivar_attribute {
struct attribute attr;
ssize_t (*show) (struct efivar_entry *entry, char *buf);
@ -386,9 +384,6 @@ static struct sysfs_ops efivar_attr_ops = {
static void efivar_release(struct kobject *kobj)
{
struct efivar_entry *var = container_of(kobj, struct efivar_entry, kobj);
spin_lock(&efivars_lock);
list_del(&var->list);
spin_unlock(&efivars_lock);
kfree(var);
}
@ -430,9 +425,8 @@ static ssize_t
efivar_create(struct subsystem *sub, const char *buf, size_t count)
{
struct efi_variable *new_var = (struct efi_variable *)buf;
struct efivar_entry *search_efivar = NULL;
struct efivar_entry *search_efivar, *n;
unsigned long strsize1, strsize2;
struct list_head *pos, *n;
efi_status_t status = EFI_NOT_FOUND;
int found = 0;
@ -444,8 +438,7 @@ efivar_create(struct subsystem *sub, const char *buf, size_t count)
/*
* Does this variable already exist?
*/
list_for_each_safe(pos, n, &efivar_list) {
search_efivar = get_efivar_entry(pos);
list_for_each_entry_safe(search_efivar, n, &efivar_list, list) {
strsize1 = utf8_strsize(search_efivar->var.VariableName, 1024);
strsize2 = utf8_strsize(new_var->VariableName, 1024);
if (strsize1 == strsize2 &&
@ -490,9 +483,8 @@ static ssize_t
efivar_delete(struct subsystem *sub, const char *buf, size_t count)
{
struct efi_variable *del_var = (struct efi_variable *)buf;
struct efivar_entry *search_efivar = NULL;
struct efivar_entry *search_efivar, *n;
unsigned long strsize1, strsize2;
struct list_head *pos, *n;
efi_status_t status = EFI_NOT_FOUND;
int found = 0;
@ -504,8 +496,7 @@ efivar_delete(struct subsystem *sub, const char *buf, size_t count)
/*
* Does this variable already exist?
*/
list_for_each_safe(pos, n, &efivar_list) {
search_efivar = get_efivar_entry(pos);
list_for_each_entry_safe(search_efivar, n, &efivar_list, list) {
strsize1 = utf8_strsize(search_efivar->var.VariableName, 1024);
strsize2 = utf8_strsize(del_var->VariableName, 1024);
if (strsize1 == strsize2 &&
@ -537,9 +528,9 @@ efivar_delete(struct subsystem *sub, const char *buf, size_t count)
spin_unlock(&efivars_lock);
return -EIO;
}
list_del(&search_efivar->list);
/* We need to release this lock before unregistering. */
spin_unlock(&efivars_lock);
efivar_unregister(search_efivar);
/* It's dead Jim.... */
@ -768,10 +759,14 @@ out_free:
static void __exit
efivars_exit(void)
{
struct list_head *pos, *n;
struct efivar_entry *entry, *n;
list_for_each_safe(pos, n, &efivar_list)
efivar_unregister(get_efivar_entry(pos));
list_for_each_entry_safe(entry, n, &efivar_list, list) {
spin_lock(&efivars_lock);
list_del(&entry->list);
spin_unlock(&efivars_lock);
efivar_unregister(entry);
}
subsystem_unregister(&vars_subsys);
firmware_unregister(&efi_subsys);