Description
In the Linux kernel, the following vulnerability has been resolved: rseq: Fix segfault on registration when rseq_cs is non-zero The rseq_cs field is documented as being set to 0 by user-space prior to registration, however this is not currently enforced by the kernel. This can result in a segfault on return to user-space if the value stored in the rseq_cs field doesn't point to a valid struct rseq_cs. The correct solution to this would be to fail the rseq registration when the rseq_cs field is non-zero. However, some older versions of glibc will reuse the rseq area of previous threads without clearing the rseq_cs field and will also terminate the process if the rseq registration fails in a secondary thread. This wasn't caught in testing because in this case the leftover rseq_cs does point to a valid struct rseq_cs. What we can do is clear the rseq_cs field on registration when it's non-zero which will prevent segfaults on registration and won't break the glibc versions that reuse rseq areas on thread creation.
Affected products
Version statuses are supplied by the assigning organization. Consult the original record for detailed ranges and platform conditions.
Linux Linux
Default version status: unaffected
d7822b1e24f2df5df98c76f0e94a5416349ff759 to < 48900d839a3454050fd5822e34be8d54c4ec9b86affectedd7822b1e24f2df5df98c76f0e94a5416349ff759 to < 3e4028ef31b69286c9d4878cee0330235f53f218affectedd7822b1e24f2df5df98c76f0e94a5416349ff759 to < b2b05d0dc2f4f0646922068af435aed5763d16baaffectedd7822b1e24f2df5df98c76f0e94a5416349ff759 to < eaf112069a904b6207b4106ff083e0208232a2ebaffectedd7822b1e24f2df5df98c76f0e94a5416349ff759 to < f004f58d18a2d3dc761cf973ad27b4a5997bd876affectedd7822b1e24f2df5df98c76f0e94a5416349ff759 to < 2df285dab00fa03a3ef939b6cb0d0d0aeb0791dbaffectedd7822b1e24f2df5df98c76f0e94a5416349ff759 to < fd881d0a085fc54354414aed990ccf05f282ba53affected
Linux Linux
Default version status: affected
4.18affected0 to < 4.18unaffected5.10.240 to ≤ 5.10.*unaffected5.15.189 to ≤ 5.15.*unaffected6.1.146 to ≤ 6.1.*unaffected6.6.99 to ≤ 6.6.*unaffected6.12.39 to ≤ 6.12.*unaffected6.14.9 to ≤ 6.14.*unaffected6.15 to ≤ *unaffected
References
- https://git.kernel.org/stable/c/48900d839a3454050fd5822e34be8d54c4ec9b86 ↗
- https://git.kernel.org/stable/c/3e4028ef31b69286c9d4878cee0330235f53f218 ↗
- https://git.kernel.org/stable/c/b2b05d0dc2f4f0646922068af435aed5763d16ba ↗
- https://git.kernel.org/stable/c/eaf112069a904b6207b4106ff083e0208232a2eb ↗
- https://git.kernel.org/stable/c/f004f58d18a2d3dc761cf973ad27b4a5997bd876 ↗
- https://git.kernel.org/stable/c/2df285dab00fa03a3ef939b6cb0d0d0aeb0791db ↗
- https://git.kernel.org/stable/c/fd881d0a085fc54354414aed990ccf05f282ba53 ↗
- https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html ↗
- https://lists.debian.org/debian-lts-announce/2025/10/msg00007.html ↗
- https://cert-portal.siemens.com/productcert/html/ssa-082556.html ↗