[PATCH] bug: nfsd/nfs4xdr.c misuse of ERR_PTR()

	a) ERR_PTR(nfserr_something) is a bad idea;
IS_ERR() will be false for it.
	b) mixing nfserr_.... with -EOPNOTSUPP is
even worse idea.

nfsd4_path() does both; caller expects to get NFS protocol error out it if
anything goes wrong, but if it does we either do not notice (see (a)) or get
host-endian negative (see (b)).

IOW, that's a case when we can't use ERR_PTR() to return error, even though we
return a pointer in case of success.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Acked-by: Trond Myklebust <trond.myklebust@fys.uio.no>
Acked-by: Neil Brown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
index 41fc241..77be0c4 100644 (file)
--- a/fs/nfsd/nfs4xdr.c
+++ b/fs/nfsd/nfs4xdr.c
@@ -1292,16 +1292,15 @@ static int nfsd4_encode_fs_location4(struct nfsd4_fs_location *location,
  * Returned string is safe to use as long as the caller holds a reference
  * to @exp.
  */
-static char *nfsd4_path(struct svc_rqst *rqstp, struct svc_export *exp)
+static char *nfsd4_path(struct svc_rqst *rqstp, struct svc_export *exp, u32 *stat)
 {
        struct svc_fh tmp_fh;
        char *path, *rootpath;
-       int stat;
 
        fh_init(&tmp_fh, NFS4_FHSIZE);
-       stat = exp_pseudoroot(rqstp->rq_client, &tmp_fh, &rqstp->rq_chandle);
-       if (stat)
-               return ERR_PTR(stat);
+       *stat = exp_pseudoroot(rqstp->rq_client, &tmp_fh, &rqstp->rq_chandle);
+       if (*stat)
+               return NULL;
        rootpath = tmp_fh.fh_export->ex_path;
 
        path = exp->ex_path;
@@ -1309,7 +1308,8 @@ static char *nfsd4_path(struct svc_rqst *rqstp, struct svc_export *exp)
        if (strncmp(path, rootpath, strlen(rootpath))) {
                printk("nfsd: fs_locations failed;"
                        "%s is not contained in %s\n", path, rootpath);
-               return ERR_PTR(-EOPNOTSUPP);
+               *stat = nfserr_notsupp;
+               return NULL;
        }
 
        return path + strlen(rootpath);
@@ -1322,13 +1322,14 @@ static int nfsd4_encode_fs_locations(struct svc_rqst *rqstp,
                                     struct svc_export *exp,
                                     u32 **pp, int *buflen)
 {
-       int status, i;
+       u32 status;
+       int i;
        u32 *p = *pp;
        struct nfsd4_fs_locations *fslocs = &exp->ex_fslocs;
-       char *root = nfsd4_path(rqstp, exp);
+       char *root = nfsd4_path(rqstp, exp, &status);
 
-       if (IS_ERR(root))
-               return PTR_ERR(root);
+       if (status)
+               return status;
        status = nfsd4_encode_components('/', root, &p, buflen);
        if (status)
                return status;