CVE-2026-98540

In the Linux kernel, the following vulnerability has been resolved:

fprobe: Terminate the fgraph_data list when the reservation is not filled

fprobe_fgraph_entry() reserves shadow stack space for every fprobe with

an exit handler, but only fills it for those whose entry handler returns

0. fgraph_reserve_data() does not clear the area, so fprobe_return()

parses the unused tail as headers left over from an earlier call, and an

exit handler can run twice or despite its entry handler asking to skip

it.

Write a zero word after the last entry to terminate the walk. A zeroed

slot does not decode to a NULL fprobe on the arches that encode the

header into one unsigned long, since arch_decode_fprobe_header_fp() ORs

in FPROBE_HEADER_MSB_PATTERN, so make read_fprobe_header() return NULL

for a zeroed slot.