From 954b7ac81ef503df3c1efc5566df985b08951d52 Mon Sep 17 00:00:00 2001
From: Yuta Saito <kateinoigakukun@gmail.com>
Date: Tue, 1 Aug 2023 03:56:53 +0900
Subject: [PATCH] addr2line.c: fix `DW_FORM_ref_addr` parsing for DWARF 2
 (#8146)

addr2line.c: fix DW_FORM_ref_addr parsing for DWARF 2

This fixes a crash when retrieving backtrace info with YJIT enabled on
macOS with Rust 1.71.0. Since Rust 1.71.0, the DWARF info generated by
the Rust compiler uses DW_FORM_ref_addr instead of DW_FORM_ref4 for
pointers to other DIEs.
DW_FORM_ref_addr representation in DWARF 2 is different from DWARF 3+,
so we need to handle it separately.
This patch fixes the parsing of DW_FORM_ref_addr for DWARF 2, which is
the default DWARF version Rustc uses on macOS.

See the DWARF 2.0.0 spec, section 7.5.4 Attribute Encodings
https://dwarfstd.org/doc/dwarf-2.0.0.pdf

https://bugs.ruby-lang.org/issues/19789
---
 addr2line.c | 40 ++++++++++++++++++++++++++--------------
 1 file changed, 26 insertions(+), 14 deletions(-)

diff --git a/addr2line.c b/addr2line.c
index 1616ec9855..1b261e3c5b 100644
--- a/addr2line.c
+++ b/addr2line.c
@@ -1152,19 +1152,25 @@ resolve_strx(DebugInfoReader *reader, uint64_t idx)
     return reader->obj->debug_str.ptr + off;
 }
 
+static void
+debug_info_reader_read_addr_value(DebugInfoReader *reader, DebugInfoValue *v)
+{
+    if (reader->address_size == 4) {
+        set_uint_value(v, read_uint32(&reader->p));
+    } else if (reader->address_size == 8) {
+        set_uint_value(v, read_uint64(&reader->p));
+    } else {
+        fprintf(stderr,"unknown address_size:%d", reader->address_size);
+        abort();
+    }
+}
+
 static void
 debug_info_reader_read_value(DebugInfoReader *reader, uint64_t form, DebugInfoValue *v)
 {
     switch (form) {
       case DW_FORM_addr:
-        if (reader->address_size == 4) {
-            set_uint_value(v, read_uint32(&reader->p));
-        } else if (reader->address_size == 8) {
-            set_uint_value(v, read_uint64(&reader->p));
-        } else {
-            fprintf(stderr,"unknown address_size:%d", reader->address_size);
-            abort();
-        }
+        debug_info_reader_read_addr_value(reader, v);
         break;
       case DW_FORM_block2:
         v->size = read_uint16(&reader->p);
@@ -1216,13 +1222,19 @@ debug_info_reader_read_value(DebugInfoReader *reader, uint64_t form, DebugInfoVa
         set_uint_value(v, read_uleb128(reader));
         break;
       case DW_FORM_ref_addr:
-        if (reader->format == 4) {
-            set_uint_value(v, read_uint32(&reader->p));
-        } else if (reader->format == 8) {
-            set_uint_value(v, read_uint64(&reader->p));
+        if (reader->current_version <= 2) {
+            // DWARF Version 2 specifies that references have
+            // the same size as an address on the target system
+            debug_info_reader_read_addr_value(reader, v);
         } else {
-            fprintf(stderr,"unknown format:%d", reader->format);
-            abort();
+            if (reader->format == 4) {
+                set_uint_value(v, read_uint32(&reader->p));
+            } else if (reader->format == 8) {
+                set_uint_value(v, read_uint64(&reader->p));
+            } else {
+                fprintf(stderr,"unknown format:%d", reader->format);
+                abort();
+            }
         }
         break;
       case DW_FORM_ref1: