NFSD: Fix crash encoding lock reply on 32-bit

kinglongmee · J. Bruce Fields · commit f98bac5a30b6 · 2014-07-23T10:31:56.000-04:00
Commit 8c7424c "nfsd4: don't try to encode conflicting owner if low on space" forgot to free conf->data in nfsd4_encode_lockt and before sign conf->data to NULL in nfsd4_encode_lock_denied, causing a leak. Worse, kfree() can be called on an uninitialized pointer in the case of a succesful lock (or one that fails for a reason other than a conflict). (Note that lock->lk_denied.ld_owner.data appears it should be zero here, until you notice that it's one arm of a union the other arm of which is written to in the succesful case by the memcpy(&lock->lk_resp_stateid, &lock_stp->st_stid.sc_stateid, sizeof(stateid_t)); in nfsd4_lock(). In the 32-bit case this overwrites ld_owner.data.) Signed-off-by: Kinglong Mee <kinglongmee@gmail.com> Fixes: 8c7424c ""nfsd4: don't try to encode conflicting owner if low on space" Signed-off-by: J. Bruce Fields <bfields@redhat.com>
diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
@@ -2879,6 +2879,7 @@ nfsd4_encode_lock_denied(struct xdr_stream *xdr, struct nfsd4_lock_denied *ld)
 		 * return the conflicting open:
 		 */
 		if (conf->len) {
+			kfree(conf->data);
 			conf->len = 0;
 			conf->data = NULL;
 			goto again;
@@ -2891,6 +2892,7 @@ nfsd4_encode_lock_denied(struct xdr_stream *xdr, struct nfsd4_lock_denied *ld)
 	if (conf->len) {
 		p = xdr_encode_opaque_fixed(p, &ld->ld_clientid, 8);
 		p = xdr_encode_opaque(p, conf->data, conf->len);
+		kfree(conf->data);
 	}  else {  /* non - nfsv4 lock in conflict, no clientid nor owner */
 		p = xdr_encode_hyper(p, (u64)0); /* clientid */
 		*p++ = cpu_to_be32(0); /* length of owner name */
@@ -2907,7 +2909,7 @@ nfsd4_encode_lock(struct nfsd4_compoundres *resp, __be32 nfserr, struct nfsd4_lo
 		nfserr = nfsd4_encode_stateid(xdr, &lock->lk_resp_stateid);
 	else if (nfserr == nfserr_denied)
 		nfserr = nfsd4_encode_lock_denied(xdr, &lock->lk_denied);
-	kfree(lock->lk_denied.ld_owner.data);
+
 	return nfserr;
 }
 
