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Subject[PATCH 1/25] 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 <>
fs/nfsd/nfs4xdr.c | 21 +++++++++++----------
1 files changed, 11 insertions(+), 10 deletions(-)

diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
index 41fc241..77be0c4 100644
--- a/fs/nfsd/nfs4xdr.c
+++ b/fs/nfsd/nfs4xdr.c
@@ -1292,16 +1292,15 @@ static int nfsd4_encode_fs_location4(str
* 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
if (strncmp(path, rootpath, strlen(rootpath))) {
printk("nfsd: fs_locations failed;"
"%s is not contained in %s\n", path, rootpath);
+ *stat = nfserr_notsupp;
+ return NULL;

return path + strlen(rootpath);
@@ -1322,13 +1322,14 @@ static int nfsd4_encode_fs_locations(str
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;

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