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authorJ. Bruce Fields <bfields@citi.umich.edu>2010-04-24 23:35:43 +0400
committerJ. Bruce Fields <bfields@citi.umich.edu>2010-05-03 16:32:31 +0400
commit26c0c75e69265961e891ed80b38fb62a548ab371 (patch)
tree1ecbc767a1b2ad3e8f25d88e918076806d8c2eb1 /fs/nfsd
parente0c8233622cbd49d171bc57b60e725f2fb748750 (diff)
downloadlinux-26c0c75e69265961e891ed80b38fb62a548ab371.tar.xz
nfsd4: fix unlikely race in session replay case
In the replay case, the renew_client(session->se_client); happens after we've droppped the sessionid_lock, and without holding a reference on the session; so there's nothing preventing the session being freed before we get here. Thanks to Benny Halevy for catching a bug in an earlier version of this patch. Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu> Acked-by: Benny Halevy <bhalevy@panasas.com>
Diffstat (limited to 'fs/nfsd')
-rw-r--r--fs/nfsd/nfs4proc.c1
-rw-r--r--fs/nfsd/nfs4state.c7
-rw-r--r--fs/nfsd/nfs4xdr.c10
3 files changed, 10 insertions, 8 deletions
diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c
index e147dbcb7ef7..61282f8405b5 100644
--- a/fs/nfsd/nfs4proc.c
+++ b/fs/nfsd/nfs4proc.c
@@ -1027,6 +1027,7 @@ nfsd4_proc_compound(struct svc_rqst *rqstp,
resp->rqstp = rqstp;
resp->cstate.minorversion = args->minorversion;
resp->cstate.replay_owner = NULL;
+ resp->cstate.session = NULL;
fh_init(&resp->cstate.current_fh, NFS4_FHSIZE);
fh_init(&resp->cstate.save_fh, NFS4_FHSIZE);
/* Use the deferral mechanism only for NFSv4.0 compounds */
diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index bba9fff49cfe..737315c61e7e 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -1443,11 +1443,10 @@ nfsd4_sequence(struct svc_rqst *rqstp,
cstate->slot = slot;
cstate->session = session;
- /* Hold a session reference until done processing the compound:
- * nfsd4_put_session called only if the cstate slot is set.
- */
- nfsd4_get_session(session);
out:
+ /* Hold a session reference until done processing the compound. */
+ if (cstate->session)
+ nfsd4_get_session(cstate->session);
spin_unlock(&sessionid_lock);
/* Renew the clientid on success and on replay */
if (cstate->session) {
diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
index fb27b1db007b..05bc5bd63c95 100644
--- a/fs/nfsd/nfs4xdr.c
+++ b/fs/nfsd/nfs4xdr.c
@@ -3306,10 +3306,12 @@ nfs4svc_encode_compoundres(struct svc_rqst *rqstp, __be32 *p, struct nfsd4_compo
iov = &rqstp->rq_res.head[0];
iov->iov_len = ((char*)resp->p) - (char*)iov->iov_base;
BUG_ON(iov->iov_len > PAGE_SIZE);
- if (nfsd4_has_session(cs) && cs->status != nfserr_replay_cache) {
- nfsd4_store_cache_entry(resp);
- dprintk("%s: SET SLOT STATE TO AVAILABLE\n", __func__);
- resp->cstate.slot->sl_inuse = false;
+ if (nfsd4_has_session(cs)) {
+ if (cs->status != nfserr_replay_cache) {
+ nfsd4_store_cache_entry(resp);
+ dprintk("%s: SET SLOT STATE TO AVAILABLE\n", __func__);
+ resp->cstate.slot->sl_inuse = false;
+ }
nfsd4_put_session(resp->cstate.session);
}
return 1;