tracing: Avoid NULL return from hist_field_name() on truncation

Summary

In the Linux kernel, the following vulnerability has been resolved: tracing: Avoid NULL return from hist_field_name() on truncation hist_field_name() returns "" everywhere except the fully-qualified VAR_REF/EXPR case, where snprintf() truncation returns NULL early and bypasses the bottom NULL->"" guard. Callers don't expect NULL: strcat(expr, hist_field_name(field, 0)) at trace_events_hist.c:1758 and the strcmp() in the sort-key match loop at :4804 both deref it. system and event_name are bounded by MAX_EVENT_NAME_LEN, but the field name on a VAR_REF is kstrdup'd from a histogram variable name parsed out of the trigger string and has no length cap, so a long enough var name in a fully qualified reference can reach the truncation path. Keep the length check but leave field_name as "" on overflow.

Timeline

1. Jul 19, 2026, 3:39 PM UTCCVE published

Affected versions

• Linux Linux

  Version range not reported

• Linux Linux

  From 6.6.141 · fixed in 6.6.142; From 6.12.91 · fixed in 6.12.92; From 6.18.33 · fixed in 6.18.34; From 7.0.10 · fixed in 7.0.11

References 8