diff options
author | J. Bruce Fields | 2017-05-23 12:24:40 -0400 |
---|---|---|
committer | J. Bruce Fields | 2017-05-23 14:20:58 -0400 |
commit | 9a307403d374b993061f5992a6e260c944920d0b (patch) | |
tree | cb5eb50a1bd1dd9fdb036d19a9d19963f92ddc48 /fs | |
parent | 9512a16b0e1217bbef73d276a67c28b5fbb46512 (diff) |
nfsd4: fix null dereference on replay
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>
Diffstat (limited to 'fs')
-rw-r--r-- | fs/nfsd/nfs4proc.c | 13 |
1 files changed, 6 insertions, 7 deletions
diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c index c453a1998e00..dadb3bf305b2 100644 --- a/fs/nfsd/nfs4proc.c +++ b/fs/nfsd/nfs4proc.c @@ -1769,6 +1769,12 @@ nfsd4_proc_compound(struct svc_rqst *rqstp, opdesc->op_get_currentstateid(cstate, &op->u); op->status = opdesc->op_func(rqstp, cstate, &op->u); + /* Only from SEQUENCE */ + if (cstate->status == nfserr_replay_cache) { + dprintk("%s NFS4.1 replay from cache\n", __func__); + status = op->status; + goto out; + } if (!op->status) { if (opdesc->op_set_currentstateid) opdesc->op_set_currentstateid(cstate, &op->u); @@ -1779,14 +1785,7 @@ nfsd4_proc_compound(struct svc_rqst *rqstp, if (need_wrongsec_check(rqstp)) op->status = check_nfsd_access(current_fh->fh_export, rqstp); } - encode_op: - /* Only from SEQUENCE */ - if (cstate->status == nfserr_replay_cache) { - dprintk("%s NFS4.1 replay from cache\n", __func__); - status = op->status; - goto out; - } if (op->status == nfserr_replay_me) { op->replay = &cstate->replay_owner->so_replay; nfsd4_encode_replay(&resp->xdr, op); |