CVE-2025-38067

In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> rseq: Fix segfault on registration when rseq_cs is non-zero<br /> <br /> The rseq_cs field is documented as being set to 0 by user-space prior to<br /> registration, however this is not currently enforced by the kernel. This<br /> can result in a segfault on return to user-space if the value stored in<br /> the rseq_cs field doesn&amp;#39;t point to a valid struct rseq_cs.<br /> <br /> The correct solution to this would be to fail the rseq registration when<br /> the rseq_cs field is non-zero. However, some older versions of glibc<br /> will reuse the rseq area of previous threads without clearing the<br /> rseq_cs field and will also terminate the process if the rseq<br /> registration fails in a secondary thread. This wasn&amp;#39;t caught in testing<br /> because in this case the leftover rseq_cs does point to a valid struct<br /> rseq_cs.<br /> <br /> What we can do is clear the rseq_cs field on registration when it&amp;#39;s<br /> non-zero which will prevent segfaults on registration and won&amp;#39;t break<br /> the glibc versions that reuse rseq areas on thread creation.