CVE-2026-64028

In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> tracing: Avoid NULL return from hist_field_name() on truncation<br /> <br /> hist_field_name() returns "" everywhere except the fully-qualified<br /> VAR_REF/EXPR case, where snprintf() truncation returns NULL early<br /> and bypasses the bottom NULL-&gt;"" guard. Callers don&amp;#39;t expect NULL:<br /> strcat(expr, hist_field_name(field, 0)) at trace_events_hist.c:1758<br /> and the strcmp() in the sort-key match loop at :4804 both deref it.<br /> <br /> system and event_name are bounded by MAX_EVENT_NAME_LEN, but the<br /> field name on a VAR_REF is kstrdup&amp;#39;d from a histogram variable<br /> name parsed out of the trigger string and has no length cap, so<br /> a long enough var name in a fully qualified reference can reach<br /> the truncation path.<br /> <br /> Keep the length check but leave field_name as "" on overflow.