[PATCH v2 0/6] bitmap: fix three parsing bugs in bitmap_parse() and bitmap_parselist()

[Shashank Mohan Jain <jain.sm@gmail.com>]

This series fixes three cases where the bitmap string parsers accept
input they are documented to reject, or produce a different mask than
the one requested.  Each fix is followed by a patch adding the failing
cases to lib/test_bitmap.c.

 1-2: bitmap_parse() treats a non-hex character directly before a chunk
      of exactly eight hex digits as a separator, so "x12345678" and
      "0x0000000f" are accepted while "0xf" is rejected.  This is a
      regression from the bitmap_parse() rework; the old __bitmap_parse()
      rejected all of them.

 3-4: bitmap_parselist() does not check for the end of the region after
      the group size of a "range:used/group" region, so since N and
      all became valid region starts, "0-7:1/2N" or "0-7:1/2all" are
      silently parsed as two regions.

 5-6: bitmap_parselist() walks a "range:used/group" region with an
      unsigned int that wraps around when the group size is close to
      UINT_MAX, setting bits below the requested range.  This needs an
      absurd group size and never writes out of bounds.

With the series applied, test_bitmap reports "all 391544 tests passed"
(UML, x86_64).  The three fixes are independent and can be applied in
any order.

These patches were prepared with Claude Code (Anthropic), model Claude Opus 5.5
(claude-opus-5-5): the analysis, the Lean models used to find and check the bugs,
the fixes and the tests. I reviewed them and take responsibility for them. The
trailer only says "Assisted-by: LLM", as Documentation/process/coding-assistants.rst
requires since commit 816d9992d9ed ("coding-assistants: simplify attribution").

Changes in v2:
- Resent with my full name, as asked by Yury.
- Stated the tool and model used above.
- No code changes.

v1: https://lore.kernel.org/r/20260925102307.49513-1-jain.sm@gmail.com


smjain (6):
  bitmap: bitmap_parse(): reject non-hex character before 8 digits
  bitmap: test bitmap_parse() with an illegal character before 8 hex
    digits
  bitmap: bitmap_parselist(): reject trailing characters after group
    size
  bitmap: test bitmap_parselist() with text after the group size
  bitmap: bitmap_parselist(): don't wrap around on a huge group size
  bitmap: test bitmap_parselist() with a group size close to UINT_MAX

 lib/bitmap-str.c  | 24 +++++++++++++++++++-----
 lib/test_bitmap.c |  9 +++++++++
 2 files changed, 28 insertions(+), 5 deletions(-)

-- 
2.43.0