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

[Ian Rogers]

On Mon, May 4, 2026 at 4:50 PM Namhyung Kim <namhyung@xxxxxxxxxx> wrote:
>
> Hi Ian,
>
> Just updated Masami's email address.  Please use it for later.

Thanks Namhyung, I'll make sure in the future. For Masami's benefit
here are the LKML posts:
https://lore.kernel.org/linux-perf-users/afkw4MARqVAYOB2p@xxxxxxxxxx/T/#mb887c8aadf50c0371c4cb9273b9a7777591ad99e

The sashiko reviews (the 1 "critical" issue isn't an issue as
mentioned in a separate thread [1]):
https://sashiko.dev/#/patchset/20260504081227.2203848-1-irogers%40google.com

I think the series is ready to land and given that it fixes crashes we
may want to cherry-pick it for 7.1.

Thanks,
Ian

[1] https://lore.kernel.org/linux-perf-users/afkw4MARqVAYOB2p@xxxxxxxxxx/T/#mc177f9ef695805b013fce3fecbea7d84dfa937fd

> Thanks,
> Namhyung
>
> On Mon, May 04, 2026 at 01:12:18AM -0700, Ian Rogers wrote:
> > 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@xxxxxxxxxx/
> >
> > v3:
> >  - Minor formatting fixes.
> > https://lore.kernel.org/linux-perf-users/20260503003552.1063540-1-irogers@xxxxxxxxxx/
> >
> > v2:
> > https://lore.kernel.org/lkml/20260502155656.478642-1-irogers@xxxxxxxxxx/
> >
> > v1:
> > https://lore.kernel.org/linux-perf-users/20260502064839.282422-1-irogers@xxxxxxxxxx/
> >
> > 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(-)
> >
> > --
> > 2.54.0.545.g6539524ca2-goog
> >