In the Linux kernel, the following vulnerability has been resolved: fprobe: Terminate the fgraph_data list when the reservation is not filled… (CVE-2026-98540)

The Linux kernel's fprobe_fgraph_entry() function reserves shadow stack space for every fprobe with an exit handler but only fills it when the entry handler returns 0. Because fgraph_reserve_data() does not clear this reserved area, fprobe_return() may parse leftover data as valid headers, leading to an exit handler executing twice or executing despite being skipped. The vulnerability is mitigated by writing a zero word after the last valid entry to terminate the list, ensuring that read_fprobe_header() returns NULL for zeroed slots and preventing erroneous handler execution.

This vulnerability could cause an fprobe exit handler to execute twice or execute when it should be skipped, potentially leading to unexpected behavior in kernel tracing or monitoring functions. There is no indication of direct security compromise such as privilege escalation or code execution from the provided data.

A fix has been implemented that writes a zero word after the last valid fgraph_data entry to terminate the list properly. Users should apply the official Linux kernel update that includes this fix once available. Patch status is not explicitly confirmed in the provided data; check the vendor advisory for current remediation guidance.