[PATCH] efi-pstore: Fix read iter after pstore API refactor

[Kees Cook]

During the internal pstore API refactoring, the EFI vars read entry was
accidentally made to update a stack variable instead of the pstore
private data pointer. This corrects the problem (and removes the now
needless argument).

Signed-off-by: Kees Cook <keesc...@chromium.org>
---
 drivers/firmware/efi/efi-pstore.c | 26 ++++++++++----------------
 1 file changed, 10 insertions(+), 16 deletions(-)

diff --git a/drivers/firmware/efi/efi-pstore.c 
b/drivers/firmware/efi/efi-pstore.c
index 93d8cdbe7ef4..9e6f14c354f1 100644
--- a/drivers/firmware/efi/efi-pstore.c
+++ b/drivers/firmware/efi/efi-pstore.c
@@ -155,25 +155,20 @@ static int efi_pstore_scan_sysfs_exit(struct efivar_entry 
*pos,
  * efi_pstore_sysfs_entry_iter
  *
  * @record: pstore record to pass to callback
- * @pos: entry to begin iterating from
  *
  * You MUST call efivar_enter_iter_begin() before this function, and
  * efivar_entry_iter_end() afterwards.
  *
- * It is possible to begin iteration from an arbitrary entry within
- * the list by passing @pos. @pos is updated on return to point to
- * the next entry of the last one passed to efi_pstore_read_func().
- * To begin iterating from the beginning of the list @pos must be %NULL.
  */
-static int efi_pstore_sysfs_entry_iter(struct pstore_record *record,
-                                      struct efivar_entry **pos)
+static int efi_pstore_sysfs_entry_iter(struct pstore_record *record)
 {
+       struct efivar_entry *pos = (struct efivar_entry *)record->psi->data;
        struct efivar_entry *entry, *n;
        struct list_head *head = &efivar_sysfs_list;
        int size = 0;
        int ret;
 
-       if (!*pos) {
+       if (!pos) {
                list_for_each_entry_safe(entry, n, head, list) {
                        efi_pstore_scan_sysfs_enter(entry, n, head);
 
@@ -185,21 +180,21 @@ static int efi_pstore_sysfs_entry_iter(struct 
pstore_record *record,
                        if (size)
                                break;
                }
-               *pos = n;
+               pos = n;
                return size;
        }
 
-       list_for_each_entry_safe_from((*pos), n, head, list) {
-               efi_pstore_scan_sysfs_enter((*pos), n, head);
+       list_for_each_entry_safe_from(pos, n, head, list) {
+               efi_pstore_scan_sysfs_enter(pos, n, head);
 
-               size = efi_pstore_read_func((*pos), record);
-               ret = efi_pstore_scan_sysfs_exit((*pos), n, head, size < 0);
+               size = efi_pstore_read_func(pos, record);
+               ret = efi_pstore_scan_sysfs_exit(pos, n, head, size < 0);
                if (ret)
                        return ret;
                if (size)
                        break;
        }
-       *pos = n;
+       pos = n;
        return size;
 }
 
@@ -218,7 +213,6 @@ static int efi_pstore_sysfs_entry_iter(struct pstore_record 
*record,
  */
 static ssize_t efi_pstore_read(struct pstore_record *record)
 {
-       struct efivar_entry *entry = (struct efivar_entry *)record->psi->data;
        ssize_t size;
 
        record->buf = kzalloc(EFIVARS_DATA_SIZE_MAX, GFP_KERNEL);
@@ -229,7 +223,7 @@ static ssize_t efi_pstore_read(struct pstore_record *record)
                size = -EINTR;
                goto out;
        }
-       size = efi_pstore_sysfs_entry_iter(record, &entry);
+       size = efi_pstore_sysfs_entry_iter(record);
        efivar_entry_iter_end();
 
 out:
-- 
2.7.4


-- 
Kees Cook
Pixel Security
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