libceph: Avoid using invalid osd indices from primary_temp

In the Linux kernel, the following vulnerability has been resolved: libceph: Avoid using invalid osd indices from primary_temp A corrupted osdmap received from a Ceph monitor or OSD may contain osd indices in its pg_temp, primary_temp, pg_upmap, and pg_upmap_items parts that don't exist, i.e., that are greater than max_osd or smaller than CEPH_HOMELESS_OSD (-1). These indices are used to create the up and acting set in ceph_pg_to_up_acting_osds(), called from calc_target(). While most of these osd indices are checked, the one from primary_temp is not. Subsequently, this may lead to calc_target() returning this (potentially invalid) index as target osd for a (linger) request. Because the osd_state, osd_weight, and osd_addr arrays only contain max_osd entries (with indices 0 to max_osd -1), this leads to out-of-bounds accesses when trying to read values from these arrays. This patch fixes the issue by adding a check to get_temp_osds(), so that only valid osd indices from primary_temp are used, and it falls back to using the primary from pg_temp or the up set if it is invalid. [ idryomov: changelog ]