[PATCH v3 0/4] perf: Fix and optimize maps parsing, boundaries, and bounds safety

[Ian Rogers <irogers@google.com>]

It turns out that PATH_MAX is respected by system calls but isn't
respected by file paths in /proc/pid/maps and /proc/pid/smaps. In the
kernel "//toolong" is placed in the filename of mmap/mmap2 events
where the filename is longer than PATH_MAX, do the same in the
mmap/mmap2 synthesis code to avoid overrunning the event buffer. With
Gemini's help try to address other correctness and overrun issues.

V3 addresses Sashiko AI review feedback:
- Updates io__drain_line() loop condition from a while loop to a
  do-while loop to ensure that when ch == -2 (initial character
  non-hex/dec failure), the loop correctly reads and discards
  characters from io__get_char(io) until a newline or EOF is reached,
  preserving map line synchronization.

V2 addresses community review feedback:
- Corrects read_proc_maps_line() and io__drain_line() to safely handle
  already consumed newlines, preventing valid map data from being skipped.
- Restores the early exit block for timeouts so the TIMEOUT flag is
  always emitted to tools.
- Removes an unused assignment to avoid promoting warnings to build errors.
- Clarifies and dynamically computes the maximum filename length boundaries
  using offsetof() to prevent E2BIG errors regardless of struct layout.

Ian Rogers (4):
  perf find-map: Remove PATH_MAX 128-byte stack array restriction
  perf synthetic-events: Fix line synchronization, bounds, and
    truncation bugs in proc maps reader
  perf synthetic-events: Fix bounds, stale state, and misc flags in
    kernel module synthesis
  perf synthetic-events: Fix bounds and union member access in mmap2
    build_id synthesis

 tools/perf/util/find-map.c         |  10 +-
 tools/perf/util/synthetic-events.c | 288 ++++++++++++++++++++---------
 2 files changed, 208 insertions(+), 90 deletions(-)

-- 
2.55.0.229.g6434b31f56-goog