[PATCH v5 0/9] [PATCH v5 0/9] perf DWARF: Fix libdw API contract violations and crashes

Ian Rogers
2026-05-04T08:12:33Z

This patch series addresses a number of DWARF/libdw error-handling
bugs and contract violations, preventing several real Userspace
segmentation faults and memory/FD leaks.

In v5, the series has been extensively restructured and polished based on
comprehensive review feedback on v4, focusing on history granularity,
bisectability, and defensive styling:

- **Commit Splitting for Review Granularity**: Split the previously large
libdw contract fix patch into 4 granular commits to cleanly isolate
independent improvements: introducing clear_frames refactoring, fixing
ORDER_CALLER parent update corruption, adding line 0 support, and
consolidating core contract/leak cleanups.

- **Bisectability & Correctness Hardening**:
- Fixed an unused variable compilation failure (-Werror) in the split
history to guarantee perfect git bisectability.
- Fixed a line 0 fallback regression to ensure that if an optional call
line is missing but the call file is valid, we fallback to line 0
to preserve the filename rather than discarding the caller info entirely.

- **Style & Robustness Polish**:
- Standardized all newly introduced C++ style (//) comments to
preferred C style (/* ... */) comments.
- Implemented explicit safe string duplication style fix in annotate-data.
- Corrected CU DIE propagation context inside probe-finder.
- Enhanced the Patch 2 commit message to explicitly detail the removal
of strict optional attribute aborts (decf) to clarify review queries.

- **Tags Collected**: Integrated Acked-by tags from Namhyung Kim for Patch 1
and Patch 9.

v5:
- Restructured series from 6 to 9 patches by splitting the libdw commit.
- Fixed compilation bisectability and DWARF line 0 filename preservation regressions.
- Standardized comment styles and applied safe duplication formatting fixes.
- Updated commit messages with detailed optional attribute justifications.

v4:
- Localized and squashed robust error handling, memory/FD cleanup
paths, and safe DWARF printing.
https://lore.kernel.org/linux-perf-users/20260503171032.1559338-1-irogers@google.com/

v3:
- Minor formatting fixes.
https://lore.kernel.org/linux-perf-users/20260503003552.1063540-1-irogers@google.com/

v2:
https://lore.kernel.org/lkml/20260502155656.478642-1-irogers@google.com/

v1:
https://lore.kernel.org/linux-perf-users/20260502064839.282422-1-irogers@google.com/

Ian Rogers (9):
perf dwarf-aux: Fix libdw segmentation fault in cu_walk_functions_at
perf dwarf-aux: Fix libdw API contract violations
perf srcline: Introduce inline_node__clear_frames()
perf libdw: Fix callchain parent update in ORDER_CALLER mode
perf libdw: Support DWARF line 0 in inline list
perf libdw: Fix libdw API contract violations and memory leaks
perf probe-finder: Fix libdw API contract violations
perf annotate-data: Fix libdw API contract violations
perf debuginfo: Fix libdw API contract violations

tools/perf/util/annotate-data.c | 27 +++++----
tools/perf/util/debuginfo.c | 9 ++-
tools/perf/util/dwarf-aux.c | 39 ++++++------
tools/perf/util/dwarf-aux.h | 5 ++
tools/perf/util/libdw.c | 72 +++++++++++++++++-----
tools/perf/util/probe-finder.c | 102 ++++++++++++++++++++------------
tools/perf/util/srcline.c | 9 ++-
tools/perf/util/srcline.h | 1 +
8 files changed, 179 insertions(+), 85 deletions(-)

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2.54.0.545.g6539524ca2-goog