On 12 May 2017 at 22:58, Kees Cook <keescook@xxxxxxxxxxxx> wrote:
> 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 <keescook@xxxxxxxxxxxx>
Does this need a cc stable?
> ---
> 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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