Description

In the Linux kernel, the following vulnerability has been resolved: ipc/shm: serialize orphan cleanup with shm_nattch updates shm_destroy_orphaned() walks the shm idr under shm_ids(ns).rwsem, but that does not serialize all fields tested by shm_may_destroy(). In particular, shm_nattch is updated while holding shm_perm.lock, and attach paths can do that without holding the rwsem. Do not decide that an orphaned segment is unused before taking the object lock. Move the shm_may_destroy() check under shm_perm.lock, matching the other destroy paths, and unlock the segment when it no longer qualifies for removal.

References 8

• git.kernel.org https://git.kernel.org/stable/c/030bbc857bd51d4b25a90d931d3f8775ef22823a
• git.kernel.org https://git.kernel.org/stable/c/1f0d01e35dbb228084d5187212e32c91a30dcbeb
• git.kernel.org https://git.kernel.org/stable/c/2e5c6f4fd4001562781e99bbfc7f1f0127187542
• git.kernel.org https://git.kernel.org/stable/c/6560be3f6a5bb84f006f184f0c966747bb58e1a3
• git.kernel.org https://git.kernel.org/stable/c/92cda2593cf2ed25b0e9d78e5e6d8303bba1a064
• git.kernel.org https://git.kernel.org/stable/c/b1e9aef48e4d8a0c1b54fb913077b0824ed7d650
• git.kernel.org https://git.kernel.org/stable/c/b5107b4ce3ad45fcf369ee2058c8910620f4b5a8
• git.kernel.org https://git.kernel.org/stable/c/db752ebfdaf2c7f27cd9690ef48b616af068319c

Remediation