NFSv4: Fix Oopses in the fs_locations code

If the server sends us a pathname with more components than the client
limit of NFS4_PATHNAME_MAXCOMPONENTS, more server entries than the client
limit of NFS4_FS_LOCATION_MAXSERVERS, or sends a total number of
fs_locations entries than the client limit of NFS4_FS_LOCATIONS_MAXENTRIES
then we will currently Oops because the limit checks are done _after_ we've
decoded the data into the arrays.

Reported-by: fanchaoting<fanchaoting@cn.fujitsu.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

diff --git a/fs/nfs/nfs4xdr.c b/fs/nfs/nfs4xdr.c
index 650fa32..0b74489 100644 (file)
--- a/fs/nfs/nfs4xdr.c
+++ b/fs/nfs/nfs4xdr.c
@@ -3496,8 +3496,11 @@ static int decode_pathname(struct xdr_stream *xdr, struct nfs4_pathname *path)
        if (n == 0)
                goto root_path;
        dprintk("pathname4: ");
-       path->ncomponents = 0;
-       while (path->ncomponents < n) {
+       if (n > NFS4_PATHNAME_MAXCOMPONENTS) {
+               dprintk("cannot parse %d components in path\n", n);
+               goto out_eio;
+       }
+       for (path->ncomponents = 0; path->ncomponents < n; path->ncomponents++) {
                struct nfs4_string *component = &path->components[path->ncomponents];
                status = decode_opaque_inline(xdr, &component->len, &component->data);
                if (unlikely(status != 0))
@@ -3506,12 +3509,6 @@ static int decode_pathname(struct xdr_stream *xdr, struct nfs4_pathname *path)
                        pr_cont("%s%.*s ",
                                (path->ncomponents != n ? "/ " : ""),
                                component->len, component->data);
-               if (path->ncomponents < NFS4_PATHNAME_MAXCOMPONENTS)
-                       path->ncomponents++;
-               else {
-                       dprintk("cannot parse %d components in path\n", n);
-                       goto out_eio;
-               }
        }
 out:
        return status;
@@ -3556,27 +3553,23 @@ static int decode_attr_fs_locations(struct xdr_stream *xdr, uint32_t *bitmap, st
        n = be32_to_cpup(p);
        if (n <= 0)
                goto out_eio;
-       res->nlocations = 0;
-       while (res->nlocations < n) {
+       for (res->nlocations = 0; res->nlocations < n; res->nlocations++) {
                u32 m;
-               struct nfs4_fs_location *loc = &res->locations[res->nlocations];
+               struct nfs4_fs_location *loc;
 
+               if (res->nlocations == NFS4_FS_LOCATIONS_MAXENTRIES)
+                       break;
+               loc = &res->locations[res->nlocations];
                p = xdr_inline_decode(xdr, 4);
                if (unlikely(!p))
                        goto out_overflow;
                m = be32_to_cpup(p);
 
-               loc->nservers = 0;
                dprintk("%s: servers:\n", __func__);
-               while (loc->nservers < m) {
-                       struct nfs4_string *server = &loc->servers[loc->nservers];
-                       status = decode_opaque_inline(xdr, &server->len, &server->data);
-                       if (unlikely(status != 0))
-                               goto out_eio;
-                       dprintk("%s ", server->data);
-                       if (loc->nservers < NFS4_FS_LOCATION_MAXSERVERS)
-                               loc->nservers++;
-                       else {
+               for (loc->nservers = 0; loc->nservers < m; loc->nservers++) {
+                       struct nfs4_string *server;
+
+                       if (loc->nservers == NFS4_FS_LOCATION_MAXSERVERS) {
                                unsigned int i;
                                dprintk("%s: using first %u of %u servers "
                                        "returned for location %u\n",
@@ -3590,13 +3583,17 @@ static int decode_attr_fs_locations(struct xdr_stream *xdr, uint32_t *bitmap, st
                                        if (unlikely(status != 0))
                                                goto out_eio;
                                }
+                               break;
                        }
+                       server = &loc->servers[loc->nservers];
+                       status = decode_opaque_inline(xdr, &server->len, &server->data);
+                       if (unlikely(status != 0))
+                               goto out_eio;
+                       dprintk("%s ", server->data);
                }
                status = decode_pathname(xdr, &loc->rootpath);
                if (unlikely(status != 0))
                        goto out_eio;
-               if (res->nlocations < NFS4_FS_LOCATIONS_MAXENTRIES)
-                       res->nlocations++;
        }
        if (res->nlocations != 0)
                status = NFS_ATTR_FATTR_V4_LOCATIONS;