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().
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().
Metrics
Affected Vendors & Products
Advisories
No advisories yet.
Fixes
Solution
No solution given by the vendor.
Workaround
No workaround given by the vendor.
References
History
Wed, 28 Oct 2026 14:15:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| First Time appeared |
Linux linux
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| Vendors & Products |
Linux linux
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Wed, 28 Oct 2026 10:45:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| 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(). | |
| Title | tracing/histograms: Reject non-stacktrace fields for synthetic stacktrace fields | |
| First Time appeared |
Linux
Linux linux Kernel |
|
| CPEs | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | |
| Vendors & Products |
Linux
Linux linux Kernel |
|
| References |
|
Projects
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MITRE
Status: PUBLISHED
Assigner: Linux
Published:
Updated: 2026-10-28T10:35:15.577Z
Reserved: 2026-09-25T10:25:14.398Z
Link: CVE-2026-99163
Vulnrichment
No data.
NVD
Status : Received
Published: 2026-10-28T11:17:36.613
Modified: 2026-10-28T11:17:36.613
Link: CVE-2026-99163
Redhat
No data.
OpenCVE Enrichment
Updated: 2026-10-28T14:00:17Z
Weaknesses
No weakness.