tracing/histograms: Reject non-stacktrace fields for synthetic stacktrace fields
Impact
In the Linux kernel, the following vulnerability has been resolved:
Source excerpt · LinuxAffected packages
Affected products
Vendor version evidence. Product records are separate from automatic dependency matching.
Linux · Linux
Other versions: unaffected
| Version / range | Source status |
|---|---|
| 00cf3d672a9dd409418647e9f98784c339c3ff63 to before 1f36e4ddd05d540f363dbaa4c23042549f15b3ef | affected |
| 00cf3d672a9dd409418647e9f98784c339c3ff63 to before deb336ae7c7b341591a6862cf6fcfeca97c77dfd | affected |
| 00cf3d672a9dd409418647e9f98784c339c3ff63 to before a244c241593b5b38a08f0df2cb43c26574efbdcb | affected |
| b9453380c1c542fd095a4dbe9251eeba4022bbce | affected |
| 5f52389bdd9eafb63b3a2f804e02aeb17b6a5f55 | affected |
| f3baa42afeea0d5f04ad31525e861199d02210cc | affected |
| 5.10.237 to before 5.11 | affected |
| 5.15.124 to before 5.16 | affected |
| 6.1.43 to before 6.2 | affected |
Linux · Linux
Other versions: affected
| Version / range | Source status |
|---|---|
| 6.3 | affected |
| 0 to before 6.3 | unaffected |
| 6.18.59 through 6.18.* (inclusive) | unaffected |
| 7.2.13 through 7.2.* (inclusive) | unaffected |
| 7.3 through * (inclusive) | unaffected |
Original source description
In the Linux kernel, the following vulnerability has been resolved:
tracing/histograms: Reject non-stacktrace fields for synthetic stacktrace fields
In check_synth_field(), when a synthetic event field is a stacktrace (field->is_stack) and the histogram field is not a "long[" stacktrace array, validation falls through to the generic size and signedness comparison.
Because parse_synth_field() sets a stacktrace field's type to "__data_loc unsigned long[]", its size is sizeof(u64) and synth_field_signed() marks it as signed. Consequently, any 8-byte signed scalar histogram field passes the fallback check, and its scalar value is subsequently dereferenced as a kernel stacktrace pointer in get_field_size() and trace_stack().
Furthermore, checking strstr(hist_field->type, "long[") is insufficient because tracepoint fields defined with __bitmask() or __rel_bitmask() also have type "__data_loc unsigned long[]" or "__rel_loc unsigned long[]", whilst create_hist_field() treats them as 4-byte scalar values without HIST_FIELD_FL_STACKTRACE.
Propagate HIST_FIELD_FL_STACKTRACE to variable references and field variables (whilst excluding variable aliases from per-element stacktrace capture), and reject any mismatch between HIST_FIELD_FL_STACKTRACE and field->is_stack in check_synth_field().