[PATCH v7 0/2] badblocks: fix rounding bug and validate input range

[Ramesh Adhikari <adhikari.resume@gmail.com>]

Two related fixes to block/badblocks.c:

Patch 1/2 fixes the actual reported bug: round_up()/round_down() don't
modify their argument in place, they return the rounded value, and the
callers in _badblocks_set()/_badblocks_clear()/badblocks_check() were
discarding that return value. Depending on caller alignment this could
leave sectors unrounded or, in the reported case, stall the CPU with a
non-advancing cursor when reached via the nvdimm ioctl path. It also
fixes a 32-bit build breakage reported by kernel test robot, since the
old rounddown()/roundup() macros pull in 64-bit division helpers not
linked on 32-bit builds. Unchanged since v6.

Patch 2/2 hardens the same three functions against the input-range and
shift edge cases the round_up/round_down fix exposed: s + sectors
overflow, and rounding itself wrapping past ULLONG_MAX. Revised in v7
per Coly's review of v6 — see the changelog in that patch for details.
The remaining open item, bounding bb->shift where it's populated from
the on-disk MD superblock in drivers/md/md.c, is being sent separately
since it's a different file and a different root cause (missing input
validation, not a rounding bug).

Ramesh Adhikari (2):
  badblocks: fix in-place round_up/round_down usage bug
  badblocks: validate sector range and shift before rounding

 block/badblocks.c         | 40 ++++++++++++++++++++++++++++++++-------
 include/linux/badblocks.h |  6 +++++-
 2 files changed, 38 insertions(+), 8 deletions(-)

-- 
2.43.0