tracing/probes: Fix use-after-free on field name/type of events with multiple probes

Summary

In the Linux kernel, the following vulnerability has been resolved: tracing/probes: Fix use-after-free on field name/type of events with multiple probes The fields of a probe-based dynamic event (kprobe, uprobe, eprobe and fprobe events) are created in traceprobe_define_arg_fields() by handing the probe_arg name/type strings to trace_define_field(), which only stores the pointers without copying. Those strings are owned by the trace_probe and are freed when that probe is removed. An event can have several probes attached. The field list is defined only once, by the first probe that registers the event, but it is kept alive by any surviving sibling probe. Deleting just that first probe by symbol - primary A: fields are defined from A's args echo 'p:kprobes/ev vfs_read a1=$arg1' > kprobe_events append B: shares A's event call echo 'p:kprobes/ev vfs_write a1=$arg1' >> kprobe_events delete only A (matched by symbol), B survives echo '-:kprobes/ev vfs_read' >> kprobe_events frees A's args (trace_probe_cleanup() -> traceprobe_free_probe_arg()), but trace_probe_unlink() keeps the trace_probe_event because the probe list is not empty. The event call stays registered via B while its fields now reference freed memory. Any field lookup then reads it, e.g. echo 'a1 == 1' > events/kprobes/ev/filter BUG: KASAN: slab-use-after-free in strcmp+0xa7/0xb0 Call Trace: strcmp trace_find_event_field parse_pred process_preds create_filter apply_event_filter event_filter_write field->name references parg->name (kstrdup'd, freed with the probe) and, for array arguments, field->type references parg->fmt (kmalloc'd, freed with the probe) - the scalar type otherwise points at the static fmttype rodata, which is safe. Have traceprobe_define_arg_fields() duplicate the name and type strings and anchor the copies on the trace_probe_event, which embeds the event call and outlives every individual probe; trace_probe_event_free() releases them. The reproducer above triggers reliably; the field lookup and the delete both run under event_mutex, so this is a dangling reference after removal rather than a race. The issue was found by the autokbug dynamic kernel fuzzer at Tencent Yunding Lab.

Timeline

1. Sep 25, 2026, 10:24 AM UTCCVE published
2. Oct 19, 2026, 9:13 AM UTCRecord last updated

Affected versions

• Linux Linux

  From ca89bc071d5e4e981dcc52e0ca90f4500d332e42 · fixed in 38305e1b8b1ec27eef8f2d4e461e3b6c8624d494; From ca89bc071d5e4e981dcc52e0ca90f4500d332e42 · fixed in 6d6118c17bc791594cbfd9cc4936ee21073b894a; From ca89bc071d5e4e981dcc52e0ca90f4500d332e42 · fixed in a2510fcaad92b09b34574c97e8356234c6a84a9a; From ca89bc071d5e4e981dcc52e0ca90f4500d332e42 · fixed in 9379e193826f23876daccb3351fab89c87084ba3; From ca89bc071d5e4e981dcc52e0ca90f4500d332e42 · fixed in 68ae584169c7a41fc9bc4677c1d368983cf44b21; From ca89bc071d5e4e981dcc52e0ca90f4500d332e42 · fixed in 411c9080a776577664531b4f7d3ee53b7a747ba8; From ca89bc071d5e4e981dcc52e0ca90f4500d332e42 · fixed in 178ff2e011e21fbebdf57f5d58a408fe59136d82; From ca89bc071d5e4e981dcc52e0ca90f4500d332e42 · fixed in 86b7a239ec6b14a7544200ede85474c6f5526049

• Linux Linux

  5.4

• KernelLinux

  From 5.4.0 · fixed in 5.10.271; From 5.11.0 · fixed in 5.15.222; From 5.16.0 · fixed in 6.1.189; From 6.2.0 · fixed in 6.6.158; From 6.7.0 · fixed in 6.12.111; From 6.13.0 · fixed in 6.18.53; From 6.19.0 · fixed in 7.2.7

References 8