vlib: fix vlib_buffer_enqueue_to_next() overflow

vlib_buffer_enqueue_to_next() requires to allow overflow of up to 63
elements of 'buffer' and 'nexts' array.
 - add helper to compute the minimum size
 - fix occurences in session and async crypto

Type: fix

Change-Id: If8d7eebc5bf9beba71ba194aec0f79b8eb6d5843
Signed-off-by: Benoît Ganne <bganne@cisco.com>

1 files changed, 25 insertions, 0 deletions

diff --git a/src/vlib/buffer_node.h b/src/vlib/buffer_node.h
index 9ca43d425fc..10ebd253c1b 100644
--- a/src/vlib/buffer_node.h
+++ b/src/vlib/buffer_node.h
@@ -335,6 +335,17 @@ generic_buffer_node_inline (vlib_main_t * vm,
   return frame->n_vectors;
 }
 
+/* Minimum size for the 'buffers' and 'nexts' arrays to be used when calling
+ * vlib_buffer_enqueue_to_next().
+ * Because of optimizations, vlib_buffer_enqueue_to_next() will access
+ * past 'count' elements in the 'buffers' and 'nexts' arrays, IOW it
+ * will overflow.
+ * Those overflow elements are ignored in the final result so they do not
+ * need to be properly initialized, however if the array is allocated right
+ * before the end of a page and the next page is not mapped, accessing the
+ * overflow elements will trigger a segfault. */
+#define VLIB_BUFFER_ENQUEUE_MIN_SIZE(n) round_pow2 ((n), 64)
+
 static_always_inline void
 vlib_buffer_enqueue_to_next (vlib_main_t * vm, vlib_node_runtime_t * node,
 			     u32 * buffers, u16 * nexts, uword count)
@@ -345,6 +356,20 @@ vlib_buffer_enqueue_to_next (vlib_main_t * vm, vlib_node_runtime_t * node,
 }
 
 static_always_inline void
+vlib_buffer_enqueue_to_next_vec (vlib_main_t *vm, vlib_node_runtime_t *node,
+				 u32 **buffers, u16 **nexts, uword count)
+{
+  const u32 bl = vec_len (*buffers), nl = vec_len (*nexts);
+  const u32 c = VLIB_BUFFER_ENQUEUE_MIN_SIZE (count);
+  ASSERT (bl >= count && nl >= count);
+  vec_validate (*buffers, c);
+  vec_validate (*nexts, c);
+  vlib_buffer_enqueue_to_next (vm, node, *buffers, *nexts, count);
+  vec_set_len (*buffers, bl);
+  vec_set_len (*nexts, nl);
+}
+
+static_always_inline void
 vlib_buffer_enqueue_to_single_next (vlib_main_t * vm,
 				    vlib_node_runtime_t * node, u32 * buffers,
 				    u16 next_index, u32 count)