In the Linux kernel, the following vulnerability has been resolved:<\/p>\n
tracing\/probes: Fix use-after-free on field name\/type of events with multiple probes<\/p>\n
The fields of a probe-based dynamic event (kprobe, uprobe, eprobe and
\nfprobe events) are created in traceprobe_define_arg_fields() by handing
\nthe probe_arg name\/type strings to trace_define_field(), which only
\nstores the pointers without copying. Those strings are owned by the
\ntrace_probe and are freed when that probe is removed.<\/p>\n
An event can have several probes attached. The field list is defined
\nonly once, by the first probe that registers the event, but it is kept
\nalive by any surviving sibling probe. Deleting just that first probe by
\nsymbol –<\/p>\n
# primary A: fields are defined from A’s args
\n echo ‘p:kprobes\/ev vfs_read a1=$arg1’ > kprobe_events
\n # append B: shares A’s event call
\n echo ‘p:kprobes\/ev vfs_write a1=$arg1’ >> kprobe_events
\n # delete only A (matched by symbol), B survives
\n echo ‘-:kprobes\/ev vfs_read’ >> kprobe_events<\/p>\n
frees A’s args (trace_probe_cleanup() -> traceprobe_free_probe_arg()),
\nbut trace_probe_unlink() keeps the trace_probe_event because the probe
\nlist is not empty. The event call stays registered via B while its
\nfields now reference freed memory. Any field lookup then reads it, e.g.<\/p>\n
echo ‘a1 == 1’ > events\/kprobes\/ev\/filter<\/p>\n
BUG: KASAN: slab-use-after-free in strcmp+0xa7\/0xb0
\n Call Trace:
\n strcmp
\n trace_find_event_field
\n parse_pred
\n process_preds
\n create_filter
\n apply_event_filter
\n event_filter_write<\/p>\n
field->name references parg->name (kstrdup’d, freed with the probe) and,
\nfor array arguments, field->type references parg->fmt (kmalloc’d, freed
\nwith the probe) – the scalar type otherwise points at the static
\nfmttype rodata, which is safe.<\/p>\n
Have traceprobe_define_arg_fields() duplicate the name and type strings
\nand anchor the copies on the trace_probe_event, which embeds the event
\ncall and outlives every individual probe; trace_probe_event_free()
\nreleases them.<\/p>\n
The reproducer above triggers reliably; the field lookup and the delete
\nboth run under event_mutex, so this is a dangling reference after
\nremoval rather than a race.<\/p>\n
The issue was found by the autokbug dynamic kernel fuzzer at Tencent
\nYunding Lab.<\/p>\n","protected":false},"excerpt":{"rendered":"
In the Linux kernel, the following vulnerability has been resolved:<\/p>\n
tracing\/probes: Fix use-after-free on field name\/type of events with multiple probes<\/p>\n
The fields of a probe-based dynamic event (kp<\/p>\n","protected":false},"template":"","meta":[],"categories":[],"tags":[],"class_list":["post-29231","vuln","type-vuln","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/vuln\/29231","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/vuln"}],"about":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/types\/vuln"}],"wp:attachment":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=29231"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=29231"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=29231"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}