On Thu, Jul 09, 2020 at 12:35:13PM +0200, mwilck@xxxxxxxx wrote:
> From: Martin Wilck <mwilck@xxxxxxxx>
>
> We already avoid creating maps with empty WWID in coalesce_paths()
> as well as in ev_add_path(). The only code path where it's difficult
> to prove (although extremely unlikely) that we can't call
> dm_addmap(ACT_CREATE) with an empty WWID is update_path_groups()->
> reload_map(). To make the code easier to review and avoid ugly
> corner cases, simply refuse to create maps with a zero-length
> WWID.
>
Reviewed-by: Benjamin Marzinski <bmarzins@xxxxxxxxxx>
> Signed-off-by: Martin Wilck <mwilck@xxxxxxxx>
> ---
> libmultipath/devmapper.c | 26 +++++++++++++++-----------
> 1 file changed, 15 insertions(+), 11 deletions(-)
>
> diff --git a/libmultipath/devmapper.c b/libmultipath/devmapper.c
> index a177a54..fb7675c 100644
> --- a/libmultipath/devmapper.c
> +++ b/libmultipath/devmapper.c
> @@ -352,6 +352,12 @@ dm_addmap (int task, const char *target, struct multipath *mpp,
> char *prefixed_uuid = NULL;
> uint32_t cookie = 0;
>
> + if (task == DM_DEVICE_CREATE && strlen(mpp->wwid) == 0) {
> + condlog(1, "%s: refusing to create map with empty WWID",
> + mpp->alias);
> + return 0;
> + }
> +
> /* Need to add this here to allow 0 to be passed in udev_flags */
> udev_flags |= DM_UDEV_DISABLE_LIBRARY_FALLBACK;
>
> @@ -368,18 +374,16 @@ dm_addmap (int task, const char *target, struct multipath *mpp,
> dm_task_set_ro(dmt);
>
> if (task == DM_DEVICE_CREATE) {
> - if (strlen(mpp->wwid) > 0) {
> - prefixed_uuid = MALLOC(UUID_PREFIX_LEN +
> - strlen(mpp->wwid) + 1);
> - if (!prefixed_uuid) {
> - condlog(0, "cannot create prefixed uuid : %s",
> - strerror(errno));
> - goto addout;
> - }
> - sprintf(prefixed_uuid, UUID_PREFIX "%s", mpp->wwid);
> - if (!dm_task_set_uuid(dmt, prefixed_uuid))
> - goto freeout;
> + prefixed_uuid = MALLOC(UUID_PREFIX_LEN +
> + strlen(mpp->wwid) + 1);
> + if (!prefixed_uuid) {
> + condlog(0, "cannot create prefixed uuid : %s",
> + strerror(errno));
> + goto addout;
> }
> + sprintf(prefixed_uuid, UUID_PREFIX "%s", mpp->wwid);
> + if (!dm_task_set_uuid(dmt, prefixed_uuid))
> + goto freeout;
> dm_task_skip_lockfs(dmt);
> #ifdef LIBDM_API_FLUSH
> dm_task_no_flush(dmt);
> --
> 2.26.2
--
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