fib: Fix crash when removing a covering prefix

Type: fix

When a covering entry is removed from the table, the covered entries first see it 'updated' and then 'removed'.
the crash occurs because the covered prefixes share (simple pointer copy) the covereds hash table of path extensions. During the cervers deletion this hash table has been removed and the update of the covered crashes when recaluationg forwarding becuase it uses the free'd hash.
Fix is to refetch the shared hash table (which is NULL) when the covered is updated.

Signed-off-by: Neale Ranns <neale@graphiant.com>
Change-Id: Icefca9d7b21da975111d0e974d75f663fc0cc00c

3 files changed, 18 insertions, 10 deletions

diff --git a/src/vnet/mfib/mfib_entry.c b/src/vnet/mfib/mfib_entry.c
index 20945aa6781..244dd4fb206 100644
--- a/src/vnet/mfib/mfib_entry.c
+++ b/src/vnet/mfib/mfib_entry.c
@@ -499,7 +499,7 @@ mfib_entry_alloc (u32 fib_index,
 }
 
 static inline mfib_path_ext_t *
-mfib_entry_path_ext_find (mfib_path_ext_t *exts,
+mfib_entry_path_ext_find (uword *exts,
                           fib_node_index_t path_index)
 {
     uword *p;
diff --git a/src/vnet/mfib/mfib_entry_src.h b/src/vnet/mfib/mfib_entry_src.h
index b85c010779c..ab3cb3ebda7 100644
--- a/src/vnet/mfib/mfib_entry_src.h
+++ b/src/vnet/mfib/mfib_entry_src.h
@@ -109,7 +109,7 @@ typedef struct mfib_entry_src_t_
     /**
      * Hash table of path extensions
      */
-    mfib_path_ext_t *mfes_exts;
+    uword *mfes_exts;
 
     /**
      * Covering entry (if needed)
diff --git a/src/vnet/mfib/mfib_entry_src_rr.c b/src/vnet/mfib/mfib_entry_src_rr.c
index a6a1e0d8aa5..5f697a5fad1 100644
--- a/src/vnet/mfib/mfib_entry_src_rr.c
+++ b/src/vnet/mfib/mfib_entry_src_rr.c
@@ -20,8 +20,8 @@
 #include <vnet/fib/fib_path_list.h>
 
 static void
-mfib_entry_src_rr_deactiviate (mfib_entry_t *mfib_entry,
-                               mfib_entry_src_t *msrc)
+mfib_entry_src_rr_deactivate (mfib_entry_t *mfib_entry,
+                              mfib_entry_src_t *msrc)
 {
     mfib_entry_t *cover;
 
@@ -42,8 +42,8 @@ mfib_entry_src_rr_deactiviate (mfib_entry_t *mfib_entry,
 }
 
 static void
-mfib_entry_src_rr_activiate (mfib_entry_t *mfib_entry,
-                             mfib_entry_src_t *msrc)
+mfib_entry_src_rr_activate (mfib_entry_t *mfib_entry,
+                            mfib_entry_src_t *msrc)
 {
     mfib_entry_src_t *csrc;
     mfib_entry_t *cover;
@@ -72,8 +72,8 @@ static mfib_src_res_t
 mfib_entry_src_rr_cover_change (mfib_entry_t *mfib_entry,
                                 mfib_entry_src_t *msrc)
 {
-    mfib_entry_src_rr_deactiviate(mfib_entry, msrc);
-    mfib_entry_src_rr_activiate(mfib_entry, msrc);
+    mfib_entry_src_rr_deactivate(mfib_entry, msrc);
+    mfib_entry_src_rr_activate(mfib_entry, msrc);
 
     return (MFIB_SRC_REEVALUATE);
 }
@@ -87,6 +87,7 @@ mfib_entry_src_rr_cover_update (mfib_entry_t *mfib_entry,
      * so there's no need to check for a new one. but we do need to
      * copy down any new flags and input interfaces
      */
+    mfib_entry_src_t *csrc;
     mfib_entry_t *cover;
 
     cover = mfib_entry_get(msrc->mfes_cover);
@@ -95,6 +96,13 @@ mfib_entry_src_rr_cover_update (mfib_entry_t *mfib_entry,
     msrc->mfes_itfs = cover->mfe_itfs;
     msrc->mfes_rpf_id = cover->mfe_rpf_id;
 
+    /* The update to the cover could have removed the extensions.
+     * When a cover is removed from the table, the covereds see it first
+     * updated (to have no forwarding) and then changed
+     */
+    csrc = mfib_entry_get_best_src(cover);
+    msrc->mfes_exts = (csrc ? csrc->mfes_exts : NULL);
+
     return (MFIB_SRC_REEVALUATE);
 }
 
@@ -102,8 +110,8 @@ void
 mfib_entry_src_rr_module_init (void)
 {
     mfib_entry_src_vft mvft = {
-        .mev_activate = mfib_entry_src_rr_activiate,
-        .mev_deactivate = mfib_entry_src_rr_deactiviate,
+        .mev_activate = mfib_entry_src_rr_activate,
+        .mev_deactivate = mfib_entry_src_rr_deactivate,
         .mev_cover_change = mfib_entry_src_rr_cover_change,
         .mev_cover_update = mfib_entry_src_rr_cover_update,
     };