NFSv4: Don't decode fs_locations if we didn't ask for them...

Currently, the server can potentially cause us to Oops by returning an
fs_locations request that we didn't actually request.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

1 files changed, 14 insertions, 9 deletions

diff --git a/fs/nfs/nfs4xdr.c b/fs/nfs/nfs4xdr.c
index 4633d405a94c..ca288d115b54 100644
--- a/fs/nfs/nfs4xdr.c
+++ b/fs/nfs/nfs4xdr.c
@@ -3561,6 +3561,10 @@ static int decode_attr_fs_locations(struct xdr_stream *xdr, uint32_t *bitmap, st
         status = 0;
         if (unlikely(!(bitmap[0] & FATTR4_WORD0_FS_LOCATIONS)))
                 goto out;
+        status = -EIO;
+        /* Ignore borken servers that return unrequested attrs */
+        if (unlikely(res == NULL))
+                goto out;
         dprintk("%s: fsroot ", __func__);
         status = decode_pathname(xdr, &res->fs_path);
         if (unlikely(status != 0))
@@ -4295,6 +4299,7 @@ xdr_error:
 
 static int decode_getfattr_attrs(struct xdr_stream *xdr, uint32_t *bitmap,
                 struct nfs_fattr *fattr, struct nfs_fh *fh,
+                struct nfs4_fs_locations *fs_loc,
                 const struct nfs_server *server)
 {
         int status;
@@ -4342,9 +4347,7 @@ static int decode_getfattr_attrs(struct xdr_stream *xdr, uint32_t *bitmap,
                 goto xdr_error;
         fattr->valid |= status;
 
-        status = decode_attr_fs_locations(xdr, bitmap, container_of(fattr,
-                                                struct nfs4_fs_locations,
-                                                fattr));
+        status = decode_attr_fs_locations(xdr, bitmap, fs_loc);
         if (status < 0)
                 goto xdr_error;
         fattr->valid |= status;
@@ -4408,7 +4411,8 @@ xdr_error:
 }
 
 static int decode_getfattr_generic(struct xdr_stream *xdr, struct nfs_fattr *fattr,
-                struct nfs_fh *fh, const struct nfs_server *server)
+                struct nfs_fh *fh, struct nfs4_fs_locations *fs_loc,
+                const struct nfs_server *server)
 {
         __be32 *savep;
         uint32_t attrlen,
@@ -4427,7 +4431,7 @@ static int decode_getfattr_generic(struct xdr_stream *xdr, struct nfs_fattr *fat
         if (status < 0)
                 goto xdr_error;
 
-        status = decode_getfattr_attrs(xdr, bitmap, fattr, fh, server);
+        status = decode_getfattr_attrs(xdr, bitmap, fattr, fh, fs_loc, server);
         if (status < 0)
                 goto xdr_error;
 
@@ -4440,7 +4444,7 @@ xdr_error:
 static int decode_getfattr(struct xdr_stream *xdr, struct nfs_fattr *fattr,
                 const struct nfs_server *server)
 {
-        return decode_getfattr_generic(xdr, fattr, NULL, server);
+        return decode_getfattr_generic(xdr, fattr, NULL, NULL, server);
 }
 
 /*
@@ -6580,8 +6584,9 @@ static int nfs4_xdr_dec_fs_locations(struct rpc_rqst *req,
         if (status)
                 goto out;
         xdr_enter_page(xdr, PAGE_SIZE);
-        status = decode_getfattr(xdr, &res->fs_locations->fattr,
-                                 res->fs_locations->server);
+        status = decode_getfattr_generic(xdr, &res->fs_locations->fattr,
+                                         NULL, res->fs_locations,
+                                         res->fs_locations->server);
 out:
         return status;
 }
@@ -6961,7 +6966,7 @@ int nfs4_decode_dirent(struct xdr_stream *xdr, struct nfs_entry *entry,
                 goto out_overflow;
 
         if (decode_getfattr_attrs(xdr, bitmap, entry->fattr, entry->fh,
-                                        entry->server) < 0)
+                                  NULL, entry->server) < 0)
                 goto out_overflow;
         if (entry->fattr->valid & NFS_ATTR_FATTR_MOUNTED_ON_FILEID)
                 entry->ino = entry->fattr->mounted_on_fileid;