[PATCH 5.4 149/367] NFS: Guard against READDIR loop when entry names exceed MAXNAMELEN

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5.4-stable review patch.  If anyone has any objections, please let me know.


From: Benjamin Coddington <bcodding@xxxxxxxxxx>

[ Upstream commit f67b55b6588bcf9316a1e6e8d529100a5aa3ebe6 ]

Commit 64cfca85bacd asserts the only valid return values for
nfs2/3_decode_dirent should not include -ENAMETOOLONG, but for a server
that sends a filename3 which exceeds MAXNAMELEN in a READDIR response the
client's behavior will be to endlessly retry the operation.

We could map -ENAMETOOLONG into -EBADCOOKIE, but that would produce
truncated listings without any error.  The client should return an error
for this case to clearly assert that the server implementation must be

Fixes: 64cfca85bacd ("NFS: Return valid errors from nfs2/3_decode_dirent()")
Signed-off-by: Benjamin Coddington <bcodding@xxxxxxxxxx>
Signed-off-by: Anna Schumaker <Anna.Schumaker@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
 fs/nfs/nfs2xdr.c | 2 +-
 fs/nfs/nfs3xdr.c | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/nfs/nfs2xdr.c b/fs/nfs/nfs2xdr.c
index af557dc2cfe1d..6b783e2d28554 100644
--- a/fs/nfs/nfs2xdr.c
+++ b/fs/nfs/nfs2xdr.c
@@ -953,7 +953,7 @@ int nfs2_decode_dirent(struct xdr_stream *xdr, struct nfs_entry *entry,
 	error = decode_filename_inline(xdr, &entry->name, &entry->len);
 	if (unlikely(error))
-		return -EAGAIN;
 	 * The type (size and byte order) of nfscookie isn't defined in
diff --git a/fs/nfs/nfs3xdr.c b/fs/nfs/nfs3xdr.c
index 84369d51353a5..6d8768ce370d2 100644
--- a/fs/nfs/nfs3xdr.c
+++ b/fs/nfs/nfs3xdr.c
@@ -1991,7 +1991,7 @@ int nfs3_decode_dirent(struct xdr_stream *xdr, struct nfs_entry *entry,
 	error = decode_inline_filename3(xdr, &entry->name, &entry->len);
 	if (unlikely(error))
-		return -EAGAIN;
 	error = decode_cookie3(xdr, &new_cookie);
 	if (unlikely(error))

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