avcodec/vvcdec: allocate and store structs on their own within the table list

Fixes "runtime error: member access within misaligned address 0xf00 for type
'struct bar', which requires # byte alignment" errors under GCC ubsan.

Reviewed-by: Nuo Mi <nuomi2021@gmail.com>
Signed-off-by: James Almer <jamrial@gmail.com>

libavcodec/vvc/vvcdec.c

@@ -55,14 +55,6 @@ typedef struct TabList {
     l->nb_tabs++;                                        \
 } while (0)
 
-static size_t tl_size(const TabList *l)
-{
-    size_t total = 0;
-    for (int i = 0; i < l->nb_tabs; i++)
-        total += l->tabs[i].size;
-    return total;
-}
-
 static void tl_init(TabList *l, const int zero, const int realloc)
 {
     l->nb_tabs = 0;
@@ -72,32 +64,28 @@ static void tl_init(TabList *l, const int zero, const int realloc)
 
 static int tl_free(TabList *l)
 {
-    for (int i = 1; i < l->nb_tabs; i++) {
-        void **p = l->tabs[i].tab;
-        *p = NULL;
-    }
-    av_freep(l->tabs[0].tab);
+    for (int i = 0; i < l->nb_tabs; i++)
+        av_freep(l->tabs[i].tab);
+
     return 0;
 }
 
 static int tl_create(TabList *l)
 {
-    size_t size = tl_size(l);
     if (l->realloc) {
-        uint8_t *p = l->zero ? av_mallocz(size) : av_malloc(size);
-        if (!p)
-            return AVERROR(ENOMEM);
         tl_free(l);
 
-        // set pointer for each table
         for (int i = 0; i < l->nb_tabs; i++) {
             Tab *t = l->tabs + i;
-            *t->tab = p;
-            p += t->size;
+            *t->tab = l->zero ? av_mallocz(t->size) : av_malloc(t->size);
+            if (!*t->tab)
+                return AVERROR(ENOMEM);
+        }
+    } else if (l->zero) {
+        for (int i = 0; i < l->nb_tabs; i++) {
+            Tab *t = l->tabs + i;
+            memset(*t->tab, 0, t->size);
         }
-    } else {
-        if (l->zero)
-            memset(*l->tabs[0].tab, 0, size);
     }
     return 0;
 }