CVE-2026-68159libceph: bound pg_{temp,upmap,upmap_items} length to CEPH_PG_MAX_SIZE

Official description

In the Linux kernel, the following vulnerability has been resolved: libceph: bound pg_{temp,upmap,upmap_items} length to CEPH_PG_MAX_SIZE __decode_pg_temp() decodes an user-controlled length but only rejects values large enough to overflow the allocation; it does not bound it to CEPH_PG_MAX_SIZE. The helper backs both pg_temp and pg_upmap decoding, and apply_upmap()/get_temp_osds() later copy the decoded list into the fixed-size on-stack array struct ceph_osds.osds[CEPH_PG_MAX_SIZE]. A monitor that sends an OSDMap with a pg_temp/pg_upmap entry longer than 32 thus causes a stack out-of-bounds write. An OSD set for a single PG can never exceed CEPH_PG_MAX_SIZE, so reject longer entries at decode time. The bound is well below the old overflow threshold, so it also covers the allocation-size overflow the previous check guarded against. BUG: KASAN: stack-out-of-bounds in ceph_pg_to_up_acting_osds Write of size 4 ... by task exploit kasan_report (mm/kasan/report.c:595) ceph_pg_to_up_acting_osds (net/ceph/osdmap.c:2617 net/ceph/osdmap.c:2833) calc_target (net/ceph/osd_client.c:1638) __submit_request (net/ceph/osd_client.c:2394) ceph_osdc_start_request (net/ceph/osd_client.c:2490) ceph_osdc_call (net/ceph/osd_client.c:5164) rbd_dev_image_probe (drivers/block/rbd.c:6899) do_rbd_add (drivers/block/rbd.c:7138) ... kernel BUG at net/ceph/osdmap.c:2670! [ idryomov: do the same in __decode_pg_upmap_items() ]

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/66eec4af1e080b695229c9a20635648a6d12fedf
• https://git.kernel.org/stable/c/4daf06456677177f2a6044729abac59c1b49e87b
• https://git.kernel.org/stable/c/d5650ddbd4d42c1a916c8fe1a4c4cb573ef810a1
• https://git.kernel.org/stable/c/42bc06c67d94d5f2a6b33294b0c4b07d8a47c515
• https://git.kernel.org/stable/c/ebdf4b4f3b1474079980a2e5cd79ad65fb54db57
• https://git.kernel.org/stable/c/590b07ceea138d49c9b64f65d263aa902d3b4730
• https://git.kernel.org/stable/c/e36663145abd7024f0281dfb22fdef65f185845b
• https://git.kernel.org/stable/c/9f00f9cf2be293efe899db67dc5272e3a9c62717