From a2c7ad822b75bba41c0de6ad02eef2cbae09f252 Mon Sep 17 00:00:00 2001
Message-Id: <a2c7ad822b75bba41c0de6ad02eef2cbae09f252.1668864292.git.github@sicherha.de>
From: Christoph Erhardt <github@sicherha.de>
Date: Sat, 19 Nov 2022 14:01:52 +0100
Subject: [PATCH] Fix out-of-bounds error on aarch64 with `_GLIBCXX_ASSERTIONS`
 enabled (again)

The square-bracket operator of `std::span` has undefined behaviour for
out-of-bounds element accesses. Resorting to iterators yields defined
behaviour.

This issue (originally described in #298) had been fixed in the past by
commit 03ba8f93255055adaf69984c17bcfea3b22340db, but it has since
resurfaced with commit 193c245781df18e3c7d96efc1ea03e9760175681.

Signed-off-by: Christoph Erhardt <github@sicherha.de>
---
 elf/thunks.cc | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/elf/thunks.cc b/elf/thunks.cc
index 89063757..7dff795a 100644
--- a/elf/thunks.cc
+++ b/elf/thunks.cc
@@ -222,7 +222,7 @@ void create_range_extension_thunks(Context<E> &ctx, OutputSection<E> &osec) {
     thunk.offset = offset;
 
     // Scan relocations between B and C to collect symbols that need thunks.
-    tbb::parallel_for_each(&m[b], &m[c], [&](InputSection<E> *isec) {
+    tbb::parallel_for_each(m.begin() + b, m.begin() + c, [&](InputSection<E> *isec) {
       scan_rels(ctx, *isec, thunk);
     });
 
@@ -244,7 +244,7 @@ void create_range_extension_thunks(Context<E> &ctx, OutputSection<E> &osec) {
     }
 
     // Scan relocations again to fix symbol offsets in the last thunk.
-    tbb::parallel_for_each(&m[b], &m[c], [&](InputSection<E> *isec) {
+    tbb::parallel_for_each(m.begin() + b, m.begin() + c, [&](InputSection<E> *isec) {
       std::span<Symbol<E> *> syms = isec->file.symbols;
       std::span<const ElfRel<E>> rels = isec->get_rels(ctx);
       std::span<RangeExtensionRef> range_extn = isec->extra.range_extn;
-- 
2.38.1