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EFI fixes for v6.14 #3

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- Avoid physical address 0x0 for random page allocations
 
 - Add correct lockdep annotation when traversing efivarfs on resume
 
 - Avoid NULL mount in kernel_file_open() when traversing efivarfs on
   resume
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Merge tag 'efi-fixes-for-v6.14-3' of git://git.kernel.org/pub/scm/linux/kernel/git/efi/efi

Pull EFI fixes from Ard Biesheuvel:
 "Here's a final batch of EFI fixes for v6.14.

  The efivarfs ones are fixes for changes that were made this cycle.
  James's fix is somewhat of a band-aid, but it was blessed by the VFS
  folks, who are working with James to come up with something better for
  the next cycle.

   - Avoid physical address 0x0 for random page allocations

   - Add correct lockdep annotation when traversing efivarfs on resume

   - Avoid NULL mount in kernel_file_open() when traversing efivarfs on
     resume"

* tag 'efi-fixes-for-v6.14-3' of git://git.kernel.org/pub/scm/linux/kernel/git/efi/efi:
  efivarfs: fix NULL dereference on resume
  efivarfs: use I_MUTEX_CHILD nested lock to traverse variables on resume
  efi/libstub: Avoid physical address 0x0 when doing random allocation
This commit is contained in:
Linus Torvalds 2025-03-20 09:18:38 -07:00
commit a4f586a9fc
2 changed files with 53 additions and 3 deletions
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4
drivers/firmware/efi/libstub/randomalloc.c
View File

@ -75,6 +75,10 @@ efi_status_t efi_random_alloc(unsigned long size,
if (align < EFI_ALLOC_ALIGN)
align = EFI_ALLOC_ALIGN;
/* Avoid address 0x0, as it can be mistaken for NULL */
if (alloc_min == 0)
alloc_min = align;
size = round_up(size, EFI_ALLOC_ALIGN);
/* count the suitable slots in each memory map entry */

52
fs/efivarfs/super.c
View File

@ -421,7 +421,7 @@ static bool efivarfs_actor(struct dir_context *ctx, const char *name, int len,
if (err)
size = 0;
inode_lock(inode);
inode_lock_nested(inode, I_MUTEX_CHILD);
i_size_write(inode, size);
inode_unlock(inode);
@ -474,12 +474,25 @@ static int efivarfs_check_missing(efi_char16_t *name16, efi_guid_t vendor,
return err;
}
static void efivarfs_deactivate_super_work(struct work_struct *work)
{
struct super_block *s = container_of(work, struct super_block,
destroy_work);
/*
* note: here s->destroy_work is free for reuse (which
* will happen in deactivate_super)
*/
deactivate_super(s);
}
static struct file_system_type efivarfs_type;
static int efivarfs_pm_notify(struct notifier_block *nb, unsigned long action,
void *ptr)
{
struct efivarfs_fs_info *sfi = container_of(nb, struct efivarfs_fs_info,
pm_nb);
struct path path = { .mnt = NULL, .dentry = sfi->sb->s_root, };
struct path path;
struct efivarfs_ctx ectx = {
.ctx = {
.actor = efivarfs_actor,
@ -487,6 +500,7 @@ static int efivarfs_pm_notify(struct notifier_block *nb, unsigned long action,
.sb = sfi->sb,
};
struct file *file;
struct super_block *s = sfi->sb;
static bool rescan_done = true;
if (action == PM_HIBERNATION_PREPARE) {
@ -499,11 +513,43 @@ static int efivarfs_pm_notify(struct notifier_block *nb, unsigned long action,
if (rescan_done)
return NOTIFY_DONE;
/* ensure single superblock is alive and pin it */
if (!atomic_inc_not_zero(&s->s_active))
return NOTIFY_DONE;
pr_info("efivarfs: resyncing variable state\n");
/* O_NOATIME is required to prevent oops on NULL mnt */
path.dentry = sfi->sb->s_root;
/*
* do not add SB_KERNMOUNT which a single superblock could
* expose to userspace and which also causes MNT_INTERNAL, see
* below
*/
path.mnt = vfs_kern_mount(&efivarfs_type, 0,
efivarfs_type.name, NULL);
if (IS_ERR(path.mnt)) {
pr_err("efivarfs: internal mount failed\n");
/*
* We may be the last pinner of the superblock but
* calling efivarfs_kill_sb from within the notifier
* here would deadlock trying to unregister it
*/
INIT_WORK(&s->destroy_work, efivarfs_deactivate_super_work);
schedule_work(&s->destroy_work);
return PTR_ERR(path.mnt);
}
/* path.mnt now has pin on superblock, so this must be above one */
atomic_dec(&s->s_active);
file = kernel_file_open(&path, O_RDONLY | O_DIRECTORY | O_NOATIME,
current_cred());
/*
* safe even if last put because no MNT_INTERNAL means this
* will do delayed deactivate_super and not deadlock
*/
mntput(path.mnt);
if (IS_ERR(file))
return NOTIFY_DONE;