static void note_change_n(const char *p, struct branch *b, unsigned char *old_fanout)
{
	static struct strbuf uq = STRBUF_INIT;
	struct object_entry *oe;
	struct branch *s;
	unsigned char sha1[20], commit_sha1[20];
	char path[60];
	uint16_t inline_data = 0;
	unsigned char new_fanout;

	/*
	 * When loading a branch, we don't traverse its tree to count the real
	 * number of notes (too expensive to do this for all non-note refs).
	 * This means that recently loaded notes refs might incorrectly have
	 * b->num_notes == 0, and consequently, old_fanout might be wrong.
	 *
	 * Fix this by traversing the tree and counting the number of notes
	 * when b->num_notes == 0. If the notes tree is truly empty, the
	 * calculation should not take long.
	 */
	if (b->num_notes == 0 && *old_fanout == 0) {
		/* Invoke change_note_fanout() in "counting mode". */
		b->num_notes = change_note_fanout(&b->branch_tree, 0xff);
		*old_fanout = convert_num_notes_to_fanout(b->num_notes);
	}

	/* Now parse the notemodify command. */
	/* <dataref> or 'inline' */
	if (*p == ':') {
		oe = find_mark(parse_mark_ref_space(&p));
		hashcpy(sha1, oe->idx.sha1);
	} else if (skip_prefix(p, "inline ", &p)) {
		inline_data = 1;
		oe = NULL; /* not used with inline_data, but makes gcc happy */
	} else {
		if (get_sha1_hex(p, sha1))
			die("Invalid dataref: %s", command_buf.buf);
		oe = find_object(sha1);
		p += 40;
		if (*p++ != ' ')
			die("Missing space after SHA1: %s", command_buf.buf);
	}

	/* <commit-ish> */
	s = lookup_branch(p);
	if (s) {
		if (is_null_sha1(s->sha1))
			die("Can't add a note on empty branch.");
		hashcpy(commit_sha1, s->sha1);
	} else if (*p == ':') {
		uintmax_t commit_mark = parse_mark_ref_eol(p);
		struct object_entry *commit_oe = find_mark(commit_mark);
		if (commit_oe->type != OBJ_COMMIT)
			die("Mark :%" PRIuMAX " not a commit", commit_mark);
		hashcpy(commit_sha1, commit_oe->idx.sha1);
	} else if (!get_sha1(p, commit_sha1)) {
		unsigned long size;
		char *buf = read_object_with_reference(commit_sha1,
			commit_type, &size, commit_sha1);
		if (!buf || size < 46)
			die("Not a valid commit: %s", p);
		free(buf);
	} else
		die("Invalid ref name or SHA1 expression: %s", p);

	if (inline_data) {
		if (p != uq.buf) {
			strbuf_addstr(&uq, p);
			p = uq.buf;
		}
		read_next_command();
		parse_and_store_blob(&last_blob, sha1, 0);
	} else if (oe) {
		if (oe->type != OBJ_BLOB)
			die("Not a blob (actually a %s): %s",
				typename(oe->type), command_buf.buf);
	} else if (!is_null_sha1(sha1)) {
		enum object_type type = sha1_object_info(sha1, NULL);
		if (type < 0)
			die("Blob not found: %s", command_buf.buf);
		if (type != OBJ_BLOB)
			die("Not a blob (actually a %s): %s",
			    typename(type), command_buf.buf);
	}

	construct_path_with_fanout(sha1_to_hex(commit_sha1), *old_fanout, path);
	if (tree_content_remove(&b->branch_tree, path, NULL, 0))
		b->num_notes--;

	if (is_null_sha1(sha1))
		return; /* nothing to insert */

	b->num_notes++;
	new_fanout = convert_num_notes_to_fanout(b->num_notes);
	construct_path_with_fanout(sha1_to_hex(commit_sha1), new_fanout, path);
	tree_content_set(&b->branch_tree, path, sha1, S_IFREG | 0644, NULL);
}

The product performs operations on a memory buffer, but it reads from or writes to a memory location outside the buffer's intended boundary. This may result in read or write operations on unexpected memory locations that could be linked to other variables, data structures, or internal program data.