[PATCH v3 0/6] perf DWARF: Fix libdw API contract violations and crashes

[Ian Rogers <irogers@google.com>]

This patch series addresses a number of issues related to improper or
incomplete error handling when interacting with the `libdw` and
`libdwfl` APIs in the `perf` DWARF processing code.
                                                                                                 
The first patch fixes a real segmentation fault observed in `perf
kmem` (via `dwarf_child` and `dwarf_diename`) caused by
`dwarf_getfuncs` returning `-1` on error, which was not caught by the
previous `if (!dwarf_getfuncs(...))` check. This allowed uninitialized
stack memory to be returned and later dereferenced.
  
Following this discovery, a comprehensive audit of `libdw` API usage
was performed across `tools/perf/`. The remaining patches proactively
fix 28 additional instances of ignored return values or unchecked
pointers that could lead to similar uninitialized memory propagation,
crashes (e.g., via `strdup(NULL)` or `strcmp(NULL)`), or silent logic
failures.

v3:
Minor formatting fixes.

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 (6):
  perf dwarf-aux: Fix libdw segmentation fault in cu_walk_functions_at
  perf dwarf-aux: Fix libdw API contract violations
  perf libdw: Fix libdw API contract violations
  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 | 17 ++++---
 tools/perf/util/debuginfo.c     |  5 +-
 tools/perf/util/dwarf-aux.c     | 37 ++++++++------
 tools/perf/util/libdw.c         | 24 +++++++---
 tools/perf/util/probe-finder.c  | 85 ++++++++++++++++++++++-----------
 5 files changed, 109 insertions(+), 59 deletions(-)

-- 
2.54.0.545.g6539524ca2-goog