Description (CNA)
In the Linux kernel, the following vulnerability has been resolved: 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.
Affected (CNA)
| Vendor / product | Versions |
|---|---|
| Linux / Linux | affected d9b05321e21e4b218de4ce8a590bf375f58b6346 before 1dcd36420af2da5bd59306dba9caf78e3d248b1d; affected d9b05321e21e4b218de4ce8a590bf375f58b6346 before 974ac49a9a068b0591a59f65c63eb06579a13091; affected d9b05321e21e4b218de4ce8a590bf375f58b6346 before ee9dce44362b2d8132c32964656ab6dff7dfbc6a |
| Linux / Linux | affected 6.17; unaffected 0 before 6.17; unaffected 6.18.33 through 6.18.*; unaffected 7.0.10 through 7.0.*; unaffected 7.1 through * |
CWE
No CWE identifiers supplied.
References
- https://git.kernel.org/stable/c/1dcd36420af2da5bd59306dba9caf78e3d248b1d
- https://git.kernel.org/stable/c/974ac49a9a068b0591a59f65c63eb06579a13091
- https://git.kernel.org/stable/c/ee9dce44362b2d8132c32964656ab6dff7dfbc6a
ADP enrichment
A flaw was found in the Linux kernel's futex subsystem. The need_futex_hash_allocate_default() function incorrectly relies on CLONE_THREAD semantics, which can lead to non-concurrency issues when memory allocations (mm->futex_ref pcpu allocations) are shared across CLONE_VM clones, excluding vfork(). This can result in a use-after-free vulnerability in futex_hash_put, a form of memory corruption. Such vulnerabilities can potentially lead to system instability or other security impacts.
- https://access.redhat.com/security/cve/CVE-2026-52973
- https://bugzilla.redhat.com/show_bug.cgi?id=2492413
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-52973.json
- https://access.redhat.com/errata/RHSA-2026:45114
- https://access.redhat.com/errata/RHSA-2026:47040
- https://access.redhat.com/errata/RHSA-2026:62642
- https://access.redhat.com/errata/RHSA-2026:62640
No English description supplied.
No references supplied.