[PATCH 0/2] nvme: fix racy access to FDP placement ID array

[Hari Mishal <harimishal1@gmail.com>]

nvme_ns_head can be shared across multiple nvme_ns paths (multipath,
or dual-port/multi-controller subsystems). nvme_query_fdp_info()
populates head->nr_plids/head->plids the first time a namespace's
FDP configuration is registered, but nothing protects that pair from
concurrent access - two paths scanning the same namespace at the
same time can race to populate it, and depending on how the writes
interleave a concurrent reader can hit a NULL dereference or an
out-of-bounds read.

Patch 1 adds a spinlock and closes the race.

Patch 2 is a small, unrelated cleanup on code sitting right next to
what patch 1 touches: it drops a WARN_ON_ONCE that turns out to be
unreachable through any current path, since the value it guards
against is already validated upstream in the block layer and F2FS
before a bio ever carries it. Happy to drop this one or send it
separately if you'd rather keep it out of this series.

Hari Mishal (2):
  nvme: fix racy access to FDP placement ID array
  nvme: drop WARN_ON_ONCE on write_stream bounds check

 drivers/nvme/host/core.c | 63 ++++++++++++++++++++++++++--------------
 drivers/nvme/host/nvme.h |  1 +
 2 files changed, 43 insertions(+), 21 deletions(-)

-- 
2.43.0