[binutils-gdb] ubsan: dwarf2.c:2232:7: runtime error: index 16 out of bounds

[Alan Modra <amodra@sourceware.org>]

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=32011d23a879283d845993e9358f64a6e8aefa98

commit 32011d23a879283d845993e9358f64a6e8aefa98
Author: Alan Modra <amodra@gmail.com>
Date:   Wed Apr 12 09:30:26 2023 +0930

    ubsan: dwarf2.c:2232:7: runtime error: index 16 out of bounds
    
    Except it isn't out of bounds because space for a larger array has
    been allocated.
    
            * dwarf2.c (struct trie_leaf): Make ranges a C99 flexible array.
            (alloc_trie_leaf, insert_arange_in_trie): Adjust sizing.

Diff:
---
 bfd/dwarf2.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/bfd/dwarf2.c b/bfd/dwarf2.c
index d99508a96c7..b135ef09120 100644
--- a/bfd/dwarf2.c
+++ b/bfd/dwarf2.c
@@ -137,7 +137,7 @@ struct trie_leaf
   struct {
     struct comp_unit *unit;
     bfd_vma low_pc, high_pc;
-  } ranges[TRIE_LEAF_SIZE];
+  } ranges[];
 };
 
 struct trie_interior
@@ -148,7 +148,9 @@ struct trie_interior
 
 static struct trie_node *alloc_trie_leaf (bfd *abfd)
 {
-  struct trie_leaf *leaf = bfd_zalloc (abfd, sizeof (struct trie_leaf));
+  struct trie_leaf *leaf;
+  size_t amt = sizeof (*leaf) + TRIE_LEAF_SIZE * sizeof (leaf->ranges[0]);
+  leaf = bfd_zalloc (abfd, amt);
   if (leaf == NULL)
     return NULL;
   leaf->head.num_room_in_leaf = TRIE_LEAF_SIZE;
@@ -2207,9 +2209,7 @@ insert_arange_in_trie (bfd *abfd,
       const struct trie_leaf *leaf = (struct trie_leaf *) trie;
       unsigned int new_room_in_leaf = trie->num_room_in_leaf * 2;
       struct trie_leaf *new_leaf;
-      size_t amt = (sizeof (struct trie_leaf)
-		    + ((new_room_in_leaf - TRIE_LEAF_SIZE)
-		       * sizeof (leaf->ranges[0])));
+      size_t amt = sizeof (*leaf) + new_room_in_leaf * sizeof (leaf->ranges[0]);
       new_leaf = bfd_zalloc (abfd, amt);
       new_leaf->head.num_room_in_leaf = new_room_in_leaf;
       new_leaf->num_stored_in_leaf = leaf->num_stored_in_leaf;