[PATCH 0/2] omfs: detect metadata chain cycles

[이상호 <kudo3228@gmail.com>]

OMFS stores directory sibling chains and file extent continuation chains
on disk. Both chains are terminated by ~0, but the next block values are
image-controlled.

A crafted filesystem can create a cycle in either chain. Lookup of a
missing directory entry or read of a file with a cyclic extent
continuation then loops in the kernel.

This series detects cycles in both metadata chains. I verified the fixes
with crafted OMFS images:

- directory sibling self-cycle:
  unpatched kernel timed out after "statting /mnt/missing";
  patched kernel returned ELOOP.

- file extent continuation self-cycle:
  unpatched kernel timed out after "reading /mnt/loopfile";
  patched kernel returned from read with EIO.

Valid directory and file images continued to behave normally.

이상호 (2):
  omfs: detect directory sibling chain cycles
  omfs: detect file extent chain cycles

 fs/omfs/dir.c  | 64 +++++++++++++++++++++++++++++++++++++++-
 fs/omfs/file.c | 79 +++++++++++++++++++++++++++++++++++++++++++++++++-
 2 files changed, 141 insertions(+), 2 deletions(-)

-- 
2.43.0