[PATCH v4 0/6] perf DWARF: Fix libdw API contract violations and crashes

[Ian Rogers <irogers@google.com>]

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 v4, the series has been thoroughly hardened based on review
feedback for v3, fixing latent bugs and improving unwinding/search
robustness:

 - **Memory/FD Leak Fixes**: Fixed file descriptor leaks in
     `debuginfo` offline init paths, and memory leaks when `strdup` or
     inlined list appends fail during callback walks.
 
 - **Callchain Robustness**: Fixed `ORDER_CALLER` update bugs to
     prevent inline callchain corruption when nest depth >
     2. Re-implemented `die_get_data_member_location` helper with
     `dwarf_attr_integrate` to safely parse location expression
     offsets for inherited properties (specifications/origins).
 
 - **Search Robustness**: Relaxed strict `dwarf_getfuncs` error aborts
     in `probe-finder` and `line-range` loops to allow skipping
     individual corrupted CUs instead of prematurely stopping searches
     entirely. Added DWARF line 0 reference support.
 
 - **Safe DWARF Printing**: Switched to the `die_name()` safe printing
     helper globally to prevent `vfprintf(NULL)` undefined
     behavior/crashes when DWARF entities (like anonymous structs or
     tail calls) lack names.

v4:
 - Localized and squashed robust error handling, memory/FD cleanup
   paths, and safe DWARF printing.

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 (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 |  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         |  84 ++++++++++++++++++++-----
 tools/perf/util/probe-finder.c  | 105 +++++++++++++++++++++-----------
 tools/perf/util/srcline.c       |   9 ++-
 tools/perf/util/srcline.h       |   1 +
 8 files changed, 191 insertions(+), 88 deletions(-)

-- 
2.54.0.545.g6539524ca2-goog