CVE-2025-38067
rseq: Fix segfault on registration when rseq_cs is non-zero
We use these services and cookies to improve your user experience. You may opt out if you wish, however, this may limit some features on this site.
Please see our statement on Data Privacy.
rseq: Fix segfault on registration when rseq_cs is non-zero
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.
Reserved 2025-04-16 | Published 2025-06-18 | Updated 2025-07-17 | Assigner Linuxgit.kernel.org/...c/48900d839a3454050fd5822e34be8d54c4ec9b86
git.kernel.org/...c/3e4028ef31b69286c9d4878cee0330235f53f218
git.kernel.org/...c/b2b05d0dc2f4f0646922068af435aed5763d16ba
git.kernel.org/...c/eaf112069a904b6207b4106ff083e0208232a2eb
git.kernel.org/...c/f004f58d18a2d3dc761cf973ad27b4a5997bd876
git.kernel.org/...c/2df285dab00fa03a3ef939b6cb0d0d0aeb0791db
git.kernel.org/...c/fd881d0a085fc54354414aed990ccf05f282ba53
Support options
