misc: add address sanitizer heap instrumentation

Introduce AddressSanitizer support: https://github.com/google/sanitizers/
This starts with heap instrumentation. vlib_buffer, bihash and stack
instrumentation should follow.

Type: feature

Change-Id: I7f20e235b2f79db72efd0e756f22c75f717a9884
Signed-off-by: Benoît Ganne <bganne@cisco.com>

10 files changed, 145 insertions, 33 deletions

diff --git a/src/vppinfra/CMakeLists.txt b/src/vppinfra/CMakeLists.txt
index accce6d004f..1c234cce234 100644
--- a/src/vppinfra/CMakeLists.txt
+++ b/src/vppinfra/CMakeLists.txt
@@ -88,6 +88,7 @@ set(VPPINFRA_SRCS
 )
 
 set(VPPINFRA_HEADERS
+  sanitizer.h
   bihash_16_8.h
   bihash_24_8.h
   bihash_40_8.h
diff --git a/src/vppinfra/dlmalloc.c b/src/vppinfra/dlmalloc.c
index 524c57b210b..451666e4c9c 100644
--- a/src/vppinfra/dlmalloc.c
+++ b/src/vppinfra/dlmalloc.c
@@ -6,6 +6,7 @@
 */
 
 #include <vppinfra/dlmalloc.h>
+#include <vppinfra/sanitizer.h>
 
 /*------------------------------ internal #includes ---------------------- */
 
@@ -459,6 +460,7 @@ static FORCEINLINE void x86_clear_lock(int* sl) {
 
 #if !defined(USE_RECURSIVE_LOCKS) || USE_RECURSIVE_LOCKS == 0
 /* Plain spin locks use single word (embedded in malloc_states) */
+CLIB_NOSANITIZE_ADDR
 static int spin_acquire_lock(int *sl) {
   int spins = 0;
   while (*(volatile int *)sl != 0 || CAS_LOCK(sl)) {
@@ -1284,6 +1286,7 @@ static struct malloc_state _gm_;
   ((char*)(A) >= S->base && (char*)(A) < S->base + S->size)
 
 /* Return segment holding given address */
+CLIB_NOSANITIZE_ADDR
 static msegmentptr segment_holding(mstate m, char* addr) {
   msegmentptr sp = &m->seg;
   for (;;) {
@@ -1295,6 +1298,7 @@ static msegmentptr segment_holding(mstate m, char* addr) {
 }
 
 /* Return true if segment contains a segment link */
+CLIB_NOSANITIZE_ADDR
 static int has_segment_link(mstate m, msegmentptr ss) {
   msegmentptr sp = &m->seg;
   for (;;) {
@@ -1612,6 +1616,7 @@ static size_t traverse_and_check(mstate m);
 
 #if (FOOTERS && !INSECURE)
 /* Check if (alleged) mstate m has expected magic field */
+CLIB_NOSANITIZE_ADDR
 static inline int
 ok_magic (const mstate m)
 {
@@ -2078,6 +2083,7 @@ static void do_check_malloc_state(mstate m) {
 /* ----------------------------- statistics ------------------------------ */
 
 #if !NO_MALLINFO
+CLIB_NOSANITIZE_ADDR
 static struct dlmallinfo internal_mallinfo(mstate m) {
   struct dlmallinfo nm = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 };
   ensure_initialization();
@@ -2842,6 +2848,7 @@ static void* sys_alloc(mstate m, size_t nb) {
 /* -----------------------  system deallocation -------------------------- */
 
 /* Unmap and unlink any mmapped segments that don't contain used chunks */
+CLIB_NOSANITIZE_ADDR
 static size_t release_unused_segments(mstate m) {
   size_t released = 0;
   int nsegs = 0;
@@ -2889,6 +2896,7 @@ static size_t release_unused_segments(mstate m) {
   return released;
 }
 
+CLIB_NOSANITIZE_ADDR
 static int sys_trim(mstate m, size_t pad) {
   size_t released = 0;
   ensure_initialization();
@@ -2957,6 +2965,7 @@ static int sys_trim(mstate m, size_t pad) {
 /* Consolidate and bin a chunk. Differs from exported versions
    of free mainly in that the chunk need not be marked as inuse.
 */
+CLIB_NOSANITIZE_ADDR
 static void dispose_chunk(mstate m, mchunkptr p, size_t psize) {
   mchunkptr next = chunk_plus_offset(p, psize);
   if (!pinuse(p)) {
@@ -3028,6 +3037,7 @@ static void dispose_chunk(mstate m, mchunkptr p, size_t psize) {
 /* ---------------------------- malloc --------------------------- */
 
 /* allocate a large request from the best fitting chunk in a treebin */
+CLIB_NOSANITIZE_ADDR
 static void* tmalloc_large(mstate m, size_t nb) {
   tchunkptr v = 0;
   size_t rsize = -nb; /* Unsigned negation */
@@ -3099,6 +3109,7 @@ static void* tmalloc_large(mstate m, size_t nb) {
 }
 
 /* allocate a small request from the best fitting chunk in a treebin */
+CLIB_NOSANITIZE_ADDR
 static void* tmalloc_small(mstate m, size_t nb) {
   tchunkptr t, v;
   size_t rsize;
@@ -3484,6 +3495,7 @@ static mchunkptr try_realloc_chunk(mstate m, mchunkptr p, size_t nb,
   return newp;
 }
 
+CLIB_NOSANITIZE_ADDR
 static void* internal_memalign(mstate m, size_t alignment, size_t bytes) {
   void* mem = 0;
   if (alignment <  MIN_CHUNK_SIZE) /* must be at least a minimum chunk size */
@@ -4101,6 +4113,7 @@ void mspace_get_address_and_size (mspace msp, char **addrp, size_t *sizep)
   *sizep = this_seg->size;
 }
 
+CLIB_NOSANITIZE_ADDR
 int mspace_is_heap_object (mspace msp, void *p)
 {
   msegment *this_seg;
@@ -4155,6 +4168,7 @@ int mspace_enable_disable_trace (mspace msp, int enable)
   return (was_enabled);
 }
 
+CLIB_NOSANITIZE_ADDR
 int mspace_is_traced (mspace msp)
 {
   mstate ms = (mstate)msp;
@@ -4164,6 +4178,7 @@ int mspace_is_traced (mspace msp)
   return 0;
 }
 
+CLIB_NOSANITIZE_ADDR
 void* mspace_get_aligned (mspace msp,
                           unsigned long n_user_data_bytes,
                           unsigned long align,
@@ -4264,6 +4279,7 @@ void* mspace_get_aligned (mspace msp,
   return (void *) searchp;
 }
 
+CLIB_NOSANITIZE_ADDR
 void mspace_put (mspace msp, void *p_arg)
 {
   char *object_header;
@@ -4287,7 +4303,7 @@ void mspace_put (mspace msp, void *p_arg)
       mheap_put_trace ((unsigned long)p_arg, psize);
     }
 
-#if CLIB_DEBUG > 0
+#if CLIB_DEBUG > 0 && !defined(CLIB_SANITIZE_ADDR)
   /* Poison the object */
   {
     size_t psize = mspace_usable_size (object_header);
@@ -4313,6 +4329,7 @@ void mspace_put_no_offset (mspace msp, void *p_arg)
   mspace_free (msp, p_arg);
 }
 
+CLIB_NOSANITIZE_ADDR
 size_t mspace_usable_size_with_delta (const void *p)
 {
   size_t usable_size;
@@ -4338,6 +4355,7 @@ size_t mspace_usable_size_with_delta (const void *p)
   versions. This is not so nice but better than the alternatives.
 */
 
+CLIB_NOSANITIZE_ADDR
 void* mspace_malloc(mspace msp, size_t bytes) {
   mstate ms = (mstate)msp;
   if (!ok_magic(ms)) {
@@ -4452,6 +4470,7 @@ void* mspace_malloc(mspace msp, size_t bytes) {
   return 0;
 }
 
+CLIB_NOSANITIZE_ADDR
 void mspace_free(mspace msp, void* mem) {
   if (mem != 0) {
     mchunkptr p  = mem2chunk(mem);
@@ -4789,6 +4808,7 @@ size_t mspace_set_footprint_limit(mspace msp, size_t bytes) {
 }
 
 #if !NO_MALLINFO
+CLIB_NOSANITIZE_ADDR
 struct dlmallinfo mspace_mallinfo(mspace msp) {
   mstate ms = (mstate)msp;
   if (!ok_magic(ms)) {
@@ -4798,6 +4818,7 @@ struct dlmallinfo mspace_mallinfo(mspace msp) {
 }
 #endif /* NO_MALLINFO */
 
+CLIB_NOSANITIZE_ADDR
 size_t mspace_usable_size(const void* mem) {
   if (mem != 0) {
     mchunkptr p = mem2chunk(mem);
diff --git a/src/vppinfra/hash.c b/src/vppinfra/hash.c
index b6f0901dd68..6115b0cffd6 100644
--- a/src/vppinfra/hash.c
+++ b/src/vppinfra/hash.c
@@ -109,7 +109,7 @@ zap64 (u64 x, word n)
  * The above is true *unless* the extra bytes cross a page boundary
  * into unmapped or no-access space, hence the boundary crossing check.
  */
-static inline u64 __attribute__ ((no_sanitize_address))
+static inline u64
 hash_memory64 (void *p, word n_bytes, u64 state)
 {
   u64 *q = p;
@@ -154,7 +154,9 @@ hash_memory64 (void *p, word n_bytes, u64 state)
 	{
 	  if (PREDICT_TRUE (page_boundary_crossing == 0))
 	    c +=
-	      zap64 (clib_mem_unaligned (q + 2, u64), n % sizeof (u64)) << 8;
+	      zap64 (CLIB_MEM_OVERFLOW
+		     (clib_mem_unaligned (q + 2, u64), q + 2, sizeof (u64)),
+		     n % sizeof (u64)) << 8;
 	  else
 	    {
 	      clib_memcpy_fast (tmp.as_u8, q + 2, n % sizeof (u64));
@@ -168,7 +170,10 @@ hash_memory64 (void *p, word n_bytes, u64 state)
       if (n % sizeof (u64))
 	{
 	  if (PREDICT_TRUE (page_boundary_crossing == 0))
-	    b += zap64 (clib_mem_unaligned (q + 1, u64), n % sizeof (u64));
+	    b +=
+	      zap64 (CLIB_MEM_OVERFLOW
+		     (clib_mem_unaligned (q + 1, u64), q + 1, sizeof (u64)),
+		     n % sizeof (u64));
 	  else
 	    {
 	      clib_memcpy_fast (tmp.as_u8, q + 1, n % sizeof (u64));
@@ -181,7 +186,10 @@ hash_memory64 (void *p, word n_bytes, u64 state)
       if (n % sizeof (u64))
 	{
 	  if (PREDICT_TRUE (page_boundary_crossing == 0))
-	    a += zap64 (clib_mem_unaligned (q + 0, u64), n % sizeof (u64));
+	    a +=
+	      zap64 (CLIB_MEM_OVERFLOW
+		     (clib_mem_unaligned (q + 0, u64), q + 0, sizeof (u64)),
+		     n % sizeof (u64));
 	  else
 	    {
 	      clib_memcpy_fast (tmp.as_u8, q, n % sizeof (u64));
diff --git a/src/vppinfra/mem.h b/src/vppinfra/mem.h
index 14b2761c881..d4819b7f989 100644
--- a/src/vppinfra/mem.h
+++ b/src/vppinfra/mem.h
@@ -53,6 +53,7 @@
 
 #include <vppinfra/os.h>
 #include <vppinfra/string.h>	/* memcpy, clib_memset */
+#include <vppinfra/sanitizer.h>
 
 #define CLIB_MAX_MHEAPS 256
 
@@ -96,6 +97,17 @@ clib_mem_set_per_cpu_heap (u8 * new_heap)
   return old;
 }
 
+always_inline uword
+clib_mem_size_nocheck (void *p)
+{
+#if USE_DLMALLOC == 0
+  mheap_elt_t *e = mheap_user_pointer_to_elt (p);
+  return mheap_elt_data_bytes (e);
+#else
+  return mspace_usable_size_with_delta (p);
+#endif
+}
+
 /* Memory allocator which may call os_out_of_memory() if it fails */
 always_inline void *
 clib_mem_alloc_aligned_at_offset (uword size, uword align, uword align_offset,
@@ -119,29 +131,21 @@ clib_mem_alloc_aligned_at_offset (uword size, uword align, uword align_offset,
   uword offset;
   heap = mheap_get_aligned (heap, size, align, align_offset, &offset);
   clib_per_cpu_mheaps[cpu] = heap;
-
-  if (offset != ~0)
-    {
-      p = heap + offset;
-      return p;
-    }
-  else
-    {
-      if (os_out_of_memory_on_failure)
-	os_out_of_memory ();
-      return 0;
-    }
+  if (PREDICT_TRUE (offset != ~0))
+    p = heap + offset;
 #else
   p = mspace_get_aligned (heap, size, align, align_offset);
-  if (PREDICT_FALSE (p == 0))
+#endif /* USE_DLMALLOC */
+
+  if (PREDICT_FALSE (0 == p))
     {
       if (os_out_of_memory_on_failure)
 	os_out_of_memory ();
       return 0;
     }
 
+  CLIB_MEM_UNPOISON (p, size);
   return p;
-#endif /* USE_DLMALLOC */
 }
 
 /* Memory allocator which calls os_out_of_memory() when it fails */
@@ -226,6 +230,8 @@ clib_mem_free (void *p)
   /* Make sure object is in the correct heap. */
   ASSERT (clib_mem_is_heap_object (p));
 
+  CLIB_MEM_POISON (p, clib_mem_size_nocheck (p));
+
 #if USE_DLMALLOC == 0
   mheap_put (heap, (u8 *) p - heap);
 #else
@@ -254,20 +260,15 @@ clib_mem_realloc (void *p, uword new_size, uword old_size)
 always_inline uword
 clib_mem_size (void *p)
 {
-#if USE_DLMALLOC == 0
-  mheap_elt_t *e = mheap_user_pointer_to_elt (p);
   ASSERT (clib_mem_is_heap_object (p));
-  return mheap_elt_data_bytes (e);
-#else
-  ASSERT (clib_mem_is_heap_object (p));
-  return mspace_usable_size_with_delta (p);
-#endif
+  return clib_mem_size_nocheck (p);
 }
 
 always_inline void
 clib_mem_free_s (void *p)
 {
   uword size = clib_mem_size (p);
+  CLIB_MEM_UNPOISON (p, size);
   memset_s_inline (p, size, 0, size);
   clib_mem_free (p);
 }
diff --git a/src/vppinfra/mem_dlmalloc.c b/src/vppinfra/mem_dlmalloc.c
index 7a53a8bb43b..5628e2714c7 100644
--- a/src/vppinfra/mem_dlmalloc.c
+++ b/src/vppinfra/mem_dlmalloc.c
@@ -19,6 +19,7 @@
 #include <vppinfra/lock.h>
 #include <vppinfra/hash.h>
 #include <vppinfra/elf_clib.h>
+#include <vppinfra/sanitizer.h>
 
 void *clib_per_cpu_mheaps[CLIB_MAX_MHEAPS];
 
@@ -219,6 +220,7 @@ clib_mem_init (void *memory, uword memory_size)
   if (mheap_trace_main.lock == 0)
     clib_spinlock_init (&mheap_trace_main.lock);
 
+  CLIB_MEM_POISON (mspace_least_addr (heap), mspace_footprint (heap));
   return heap;
 }
 
diff --git a/src/vppinfra/pool.h b/src/vppinfra/pool.h
index 747a7170800..e6ffe1e874a 100644
--- a/src/vppinfra/pool.h
+++ b/src/vppinfra/pool.h
@@ -205,6 +205,7 @@ do {                                                                    \
 	clib_bitmap_andnoti_notrim (_pool_var (p)->free_bitmap,        \
 	                             _pool_var (i));	               	\
       _vec_len (_pool_var (p)->free_indices) = _pool_var (l) - 1;       \
+      CLIB_MEM_UNPOISON((E), sizeof((E)[0]));                           \
     }                                                                   \
   else                                                                  \
     {                                                                   \
@@ -285,10 +286,12 @@ do {                                                                    \
 /** Free an object E in pool P. */
 #define pool_put(P,E)							\
 do {									\
-  pool_header_t * _pool_var (p) = pool_header (P);			\
-  uword _pool_var (l) = (E) - (P);					\
-  ASSERT (vec_is_member (P, E));					\
-  ASSERT (! pool_is_free (P, E));					\
+  typeof (P) _pool_var(p__) = (P);			                \
+  typeof (E) _pool_var(e__) = (E);			                \
+  pool_header_t * _pool_var (p) = pool_header (_pool_var(p__));		\
+  uword _pool_var (l) = _pool_var(e__) - _pool_var(p__);		\
+  ASSERT (vec_is_member (_pool_var(p__), _pool_var(e__)));		\
+  ASSERT (! pool_is_free (_pool_var(p__), _pool_var(e__)));		\
 									\
   /* Add element to free bitmap and to free list. */			\
   _pool_var (p)->free_bitmap =						\
@@ -305,6 +308,8 @@ do {									\
     }                                                                   \
   else                                                                  \
     vec_add1 (_pool_var (p)->free_indices, _pool_var (l));		\
+                                                                        \
+  CLIB_MEM_POISON(_pool_var(e__), sizeof(_pool_var(e__)[0]));                                 \
 } while (0)
 
 /** Free pool element with given index. */
diff --git a/src/vppinfra/sanitizer.h b/src/vppinfra/sanitizer.h
new file mode 100644
index 00000000000..d099d3a941f
--- /dev/null
+++ b/src/vppinfra/sanitizer.h
@@ -0,0 +1,62 @@
+#ifndef _included_clib_sanitizer_h
+#define _included_clib_sanitizer_h
+
+#ifdef CLIB_SANITIZE_ADDR
+
+#include <sanitizer/asan_interface.h>
+#include <vppinfra/clib.h>
+
+#define CLIB_NOSANITIZE_ADDR    __attribute__((no_sanitize_address))
+#define CLIB_MEM_POISON(a, s)   ASAN_POISON_MEMORY_REGION((a), (s))
+#define CLIB_MEM_UNPOISON(a, s) ASAN_UNPOISON_MEMORY_REGION((a), (s))
+
+#define CLIB_MEM_OVERFLOW(f, src, n) \
+  ({ \
+   typeof (f) clib_mem_overflow_ret__; \
+   const void *clib_mem_overflow_src__ = (src); \
+   size_t clib_mem_overflow_n__ = (n); \
+   const void *clib_mem_overflow_start__ = __asan_region_is_poisoned((void *)clib_mem_overflow_src__, clib_mem_overflow_n__); \
+   clib_mem_overflow_n__ -= (size_t)(clib_mem_overflow_start__ - clib_mem_overflow_src__); \
+   if (clib_mem_overflow_start__) \
+     CLIB_MEM_UNPOISON(clib_mem_overflow_start__, clib_mem_overflow_n__); \
+   clib_mem_overflow_ret__ = f; \
+   if (clib_mem_overflow_start__) \
+     CLIB_MEM_POISON(clib_mem_overflow_start__, clib_mem_overflow_n__); \
+   clib_mem_overflow_ret__; \
+   })
+
+#define CLIB_MEM_OVERFLOW_LOAD(f, src) \
+  ({ \
+   typeof(src) clib_mem_overflow_load_src__ = (src); \
+   CLIB_MEM_OVERFLOW(f(clib_mem_overflow_load_src__), clib_mem_overflow_load_src__, sizeof(typeof(f(clib_mem_overflow_load_src__)))); \
+   })
+
+static_always_inline void
+CLIB_MEM_POISON_LEN (void *src, size_t oldlen, size_t newlen)
+{
+  if (oldlen > newlen)
+    CLIB_MEM_POISON (src + newlen, oldlen - newlen);
+  else if (newlen > oldlen)
+    CLIB_MEM_UNPOISON (src + oldlen, newlen - oldlen);
+}
+
+#else /* CLIB_SANITIZE_ADDR */
+
+#define CLIB_NOSANITIZE_ADDR
+#define CLIB_MEM_POISON(a, s)                   (void)(a)
+#define CLIB_MEM_UNPOISON(a, s)                 (void)(a)
+#define CLIB_MEM_OVERFLOW(a, b, c)              a
+#define CLIB_MEM_OVERFLOW_LOAD(f, src)          f(src)
+#define CLIB_MEM_POISON_LEN(a, b, c)
+
+#endif /* CLIB_SANITIZE_ADDR */
+
+#endif /* _included_clib_sanitizer_h */
+
+/*
+ * fd.io coding-style-patch-verification: ON
+ *
+ * Local Variables:
+ * eval: (c-set-style "gnu")
+ * End:
+ */
diff --git a/src/vppinfra/vec.c b/src/vppinfra/vec.c
index 32788286a63..16372e9ef22 100644
--- a/src/vppinfra/vec.c
+++ b/src/vppinfra/vec.c
@@ -58,8 +58,10 @@ vec_resize_allocate_memory (void *v,
     {
       new = clib_mem_alloc_aligned_at_offset (data_bytes, data_align, header_bytes, 1	/* yes, call os_out_of_memory */
 	);
-      data_bytes = clib_mem_size (new);
-      clib_memset (new, 0, data_bytes);
+      new_alloc_bytes = clib_mem_size (new);
+      CLIB_MEM_UNPOISON (new + data_bytes, new_alloc_bytes - data_bytes);
+      clib_memset (new, 0, new_alloc_bytes);
+      CLIB_MEM_POISON (new + data_bytes, new_alloc_bytes - data_bytes);
       v = new + header_bytes;
       _vec_len (v) = length_increment;
       return v;
@@ -75,7 +77,10 @@ vec_resize_allocate_memory (void *v,
 
   /* Need to resize? */
   if (data_bytes <= old_alloc_bytes)
-    return v;
+    {
+      CLIB_MEM_UNPOISON (v, data_bytes);
+      return v;
+    }
 
   new_alloc_bytes = (old_alloc_bytes * 3) / 2;
   if (new_alloc_bytes < data_bytes)
@@ -92,6 +97,7 @@ vec_resize_allocate_memory (void *v,
       ("vec_resize fails, length increment %d, data bytes %d, alignment %d",
        length_increment, data_bytes, data_align);
 
+  CLIB_MEM_UNPOISON (old, old_alloc_bytes);
   clib_memcpy_fast (new, old, old_alloc_bytes);
   clib_mem_free (old);
 
@@ -100,7 +106,9 @@ vec_resize_allocate_memory (void *v,
   v = new;
 
   /* Zero new memory. */
+  CLIB_MEM_UNPOISON (new + data_bytes, new_alloc_bytes - data_bytes);
   memset (v + old_alloc_bytes, 0, new_alloc_bytes - old_alloc_bytes);
+  CLIB_MEM_POISON (new + data_bytes, new_alloc_bytes - data_bytes);
 
   return v + header_bytes;
 }
diff --git a/src/vppinfra/vec.h b/src/vppinfra/vec.h
index 461c0de3347..021b2295964 100644
--- a/src/vppinfra/vec.h
+++ b/src/vppinfra/vec.h
@@ -138,6 +138,7 @@ _vec_resize_inline (void *v,
       /* Typically we'll not need to resize. */
       if (new_data_bytes <= clib_mem_size (p))
 	{
+	  CLIB_MEM_UNPOISON (v, data_bytes);
 	  vh->len += length_increment;
 	  return v;
 	}
@@ -794,6 +795,7 @@ do {								\
   if (_v(n) > 0)						\
     clib_memset ((V) + _v(l) - _v(n), 0, _v(n) * sizeof ((V)[0]));	\
   _vec_len (V) -= _v(n);					\
+  CLIB_MEM_POISON(vec_end(V), _v(n) * sizeof ((V)[0]));         \
 } while (0)
 
 /** \brief Delete the element at index I
@@ -808,6 +810,7 @@ do {						\
   if (_vec_del_i < _vec_del_l)			\
     (v)[_vec_del_i] = (v)[_vec_del_l];		\
   _vec_len (v) = _vec_del_l;			\
+  CLIB_MEM_POISON(vec_end(v), sizeof ((v)[0])); \
 } while (0)
 
 /** \brief Append v2 after v1. Result in v1.
diff --git a/src/vppinfra/vec_bootstrap.h b/src/vppinfra/vec_bootstrap.h
index 5c42e5ea914..fbb01b685ca 100644
--- a/src/vppinfra/vec_bootstrap.h
+++ b/src/vppinfra/vec_bootstrap.h
@@ -164,6 +164,7 @@ vec_aligned_header_end (void *v, uword header_bytes, uword align)
 #define vec_set_len(v, l) do {     \
     ASSERT(v);                     \
     ASSERT((l) <= vec_max_len(v)); \
+    CLIB_MEM_POISON_LEN((void *)(v), _vec_len(v) * sizeof((v)[0]), (l) * sizeof((v)[0])); \
     _vec_len(v) = (l);             \
 } while (0)
 #else /* __COVERITY__ */