提出 #495748: GNU ld 2.43 illegal read access with -w --defsym option

**Description**
A segv can occur in ld when using the -w and --defsym options with a specially crafted input file. This issue leads to memory corruption (illegal memory read access) and crashes.

**Affected Version**
GNU ld (GNU Binutils) 2.43

**Steps to Reproduce**

Build binutils 2.43 with AddressSanitizer (e.g., CFLAGS="-g -fsanitize=address" ./configure && make -j).
Run the following command:

## Version 2.43
./binutils-2.43/bins/bin/ld --version
GNU ld (GNU Binutils) 2.43
Copyright (C) 2024 Free Software Foundation, Inc.
This program is free software; you may redistribute it under the terms of
the GNU General Public License version 3 or (at your option) a later version.
This program has absolutely no warranty.

./binutils-2.43/bins/bin/ld -w --defsym ++ /tmp/poc
AddressSanitizer:DEADLYSIGNAL
=================================================================
==769419==ERROR: AddressSanitizer: SEGV on unknown address 0x000000000000 (pc 0x7ff2a429bddb bp 0x000000000000 sp 0x7fff6c1bbb70 T0)
==769419==The signal is caused by a READ memory access.
==769419==Hint: address points to the zero page.
#0 0x7ff2a429bddb in _IO_fclose /build/glibc-LcI20x/glibc-2.31/libio/iofclose.c:48:9
#1 0x55dfeaccb290 in fclose (./binutils-2.43/bins/bin/ld+0x1af290) (BuildId: d9731e405748db264b62c84ded760ba4f068cb0a)
#2 0x55dfead66a44 in load_symbols ./binutils-2.43/ld/ldlang.c:3061:7
#3 0x55dfead77304 in open_input_bfds ./binutils-2.43/ld/ldlang.c:3622:13
#4 0x55dfead739f3 in lang_process ./binutils-2.43/ld/ldlang.c:8194:3
#5 0x55dfead9e34c in main ./binutils-2.43/ld/./ldmain.c:529:3
#6 0x7ff2a423e082 in __libc_start_main /build/glibc-LcI20x/glibc-2.31/csu/../csu/libc-start.c:308:16
#7 0x55dfeac766bd in _start (./binutils-2.43/bins/bin/ld+0x15a6bd) (BuildId: d9731e405748db264b62c84ded760ba4f068cb0a)

AddressSanitizer can not provide additional info.
SUMMARY: AddressSanitizer: SEGV /build/glibc-LcI20x/glibc-2.31/libio/iofclose.c:48:9 in _IO_fclose

## binutils-gdb master branch
./binutils-gdb/bins/bin/ld --version
GNU ld (GNU Binutils) 2.44.50.20250206
Copyright (C) 2025 Free Software Foundation, Inc.
This program is free software; you may redistribute it under the terms of
the GNU General Public License version 3 or (at your option) a later version.
This program has absolutely no warranty.

./binutils-gdb/bins/bin/ld -w --defsym ++ /tmp/poc
AddressSanitizer:DEADLYSIGNAL
=================================================================
==769486==ERROR: AddressSanitizer: SEGV on unknown address 0x000000000000 (pc 0x7f7dc72ffddb bp 0x000000000000 sp 0x7ffe917681b0 T0)
==769486==The signal is caused by a READ memory access.
==769486==Hint: address points to the zero page.
#0 0x7f7dc72ffddb in _IO_fclose /build/glibc-LcI20x/glibc-2.31/libio/iofclose.c:48:9
#1 0x55c660f70d60 in fclose (./binutils-gdb/bins/bin/ld+0x3dad60) (BuildId: 5e1d51f38e544370)
#2 0x55c66100d244 in load_symbols ./binutils-gdb/ld/ldlang.c:3155:7
#3 0x55c66101e194 in open_input_bfds ./binutils-gdb/ld/ldlang.c:3722:13
#4 0x55c66101a583 in lang_process ./binutils-gdb/ld/ldlang.c:8292:3
#5 0x55c66104943c in main ./binutils-gdb/ld/./ldmain.c:533:3
#6 0x7f7dc72a2082 in __libc_start_main /build/glibc-LcI20x/glibc-2.31/csu/../csu/libc-start.c:308:16
#7 0x55c660f1c18d in _start (./binutils-gdb/bins/bin/ld+0x38618d) (BuildId: 5e1d51f38e544370)

AddressSanitizer can not provide additional info.
SUMMARY: AddressSanitizer: SEGV /build/glibc-LcI20x/glibc-2.31/libio/iofclose.c:48:9 in _IO_fclose
==769486==ABORTING

** Env **
Distributor ID: Ubuntu
Description: Ubuntu 20.04.6 LTS
Release: 20.04
Codename: focal

• ソース: ⚠️ https://sourceware.org/bugzilla/show_bug.cgi?id=32646
• ユーザー: rookie (UID 80861)
• 送信: 2025年02月06日 03:54 (2 年 ago)
• モデレーション: 2025年02月10日 12:12 (4 days later)
• ステータス: 重複
• VulDBエントリ: 295057 [GNU Binutils 2.43/2.44 format.c bfd_set_format メモリ破損]
• ポイント: 0