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MR: https://gitlab.com/redhat/centos-stream/src/kernel/centos-stream-10/-/merge_requests/2928 JIRA: https://issues.redhat.com/browse/RHEL-193520 CVE: CVE-2026-52973 This patch is a backport of the following upstream commit: commit ee9dce44362b2d8132c32964656ab6dff7dfbc6a Author: Davidlohr Bueso <dave@stgolabs.net> Date: Fri May 1 12:41:23 2026 -0700 futex: Drop CLONE_THREAD requirement for private default hash alloc Currently need_futex_hash_allocate_default() depends on strict pthread semantics, abusing CLONE_THREAD. This breaks the non-concurrency assumptions when doing the mm->futex_ref pcpu allocations, leading to bugs[0] when sharing the mm in other ways; ie: BUG: KASAN: slab-use-after-free in futex_hash_put ... where the +1 bias can end up on a percpu counter that mm->futex_ref no longer points at. Loosen the check to cover any CLONE_VM clone, except vfork(). Excluding vfork keeps the existing paths untouched (no overhead), and we can't race in the first place: either the parent is suspended and the child runs alone, or mm->futex_ref is already allocated from an earlier CLONE_VM. Link: https://lore.kernel.org/all/CAL_bE8LsmCQ-FAtYDuwbJhOkt9p2wwYQwAbMh=PifC=VsiBM6A@mail.gmail.com/ [0] Fixes: d9b05321e21e ("futex: Move futex_hash_free() back to __mmput()") Reported-by: Yiming Qian <yimingqian591@gmail.com> Signed-off-by: Davidlohr Bueso <dave@stgolabs.net> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Audra Mitchell <audra@redhat.com> Approved-by: Waiman Long <longman@redhat.com> Approved-by: Rafael Aquini <raquini@redhat.com> Approved-by: Ricardo Robaina <rrobaina@redhat.com> Approved-by: CKI KWF Bot <cki-ci-bot+kwf-gitlab-com@redhat.com> Merged-by: CKI GitLab Kmaint Pipeline Bot <26919896-cki-kmaint-pipeline-bot@users.noreply.gitlab.com>