if we receive a compound such that:
- the sessionid, slot, and sequence number in the SEQUENCE op
match a cached succesful reply with N ops, and
- the Nth operation of the compound is a PUTFH, PUTPUBFH,
PUTROOTFH, or RESTOREFH,
then nfsd4_sequence will return 0 and set cstate->status to
nfserr_replay_cache. The current filehandle will not be set. This will
cause us to call check_nfsd_access with first argument NULL.
To nfsd4_compound it looks like we just succesfully executed an
operation that set a filehandle, but the current filehandle is not set.
Fix this by moving the nfserr_replay_cache earlier. There was never any
reason to have it after the encode_op label, since the only case where
he hit that is when opdesc->op_func sets it.
Note that there are two ways we could hit this case:
- a client is resending a previously sent compound that ended
with one of the four PUTFH-like operations, or
- a client is sending a *new* compound that (incorrectly) shares
sessionid, slot, and sequence number with a previously sent
compound, and the length of the previously sent compound
happens to match the position of a PUTFH-like operation in the
new compound.
The second is obviously incorrect client behavior. The first is also
very strange--the only purpose of a PUTFH-like operation is to set the
current filehandle to be used by the following operation, so there's no
point in having it as the last in a compound.
So it's likely this requires a buggy or malicious client to reproduce.
Reported-by: Scott Mayhew <smayhew@redhat.com>
Cc: stable@kernel.vger.org
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
9a307403d3