https://sourceware.org/bugzilla/show_bug.cgi?id=34805

            Bug ID: 34805
           Summary: GNU ld appends an IFUNC relocation through a null
                    section buffer
           Product: binutils
           Version: 2.47
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: ld
          Assignee: unassigned at sourceware dot org
          Reporter: basavesh.shivakumar at wsu dot edu
  Target Milestone: ---

Created attachment 17125
  --> https://sourceware.org/bugzilla/attachment.cgi?id=17125&action=edit
repro

I'm reporting this bug on behalf of my team: Ananta Srikar Puranam, Emily West,
Dr. Swarn Priya, Dr. Peng Gao and Dr. Basavesh Ammanaghatta Shivakumar.

Summary
=======

A crafted x86-64 ET_REL whose referenced global hidden GNU IFUNC has reserved
st_shndx 0xfffd makes current and released ASan/UBSan GNU ld abort in
_bfd_elf_append_rela at bfd/elflink.c:15683 (2.47:15623); unsanitized GNU ld
2.42 asserts and segfaults, while the same IFUNC defined in .text links
cleanly.

Reproduction
============

1. Download and extract `bfd-ifunc-rela-append-null-pointer-reproducer.tar.gz`.
2. Run the following command with an ld.bfd or all-target `ld-new` binary that
   supports the emulation used by the reproducer:

       LD_BFD=/path/to/ld-new sh repro.sh

The archive contains the fixed input files, independent controls, helper
scripts needed by `repro.sh`, and their checksums. The script uses a temporary
directory and does not modify the source tree.

Observed result
===============

A crafted x86-64 ET_REL whose referenced global hidden GNU IFUNC has reserved
st_shndx 0xfffd makes current and released ASan/UBSan GNU ld abort in
_bfd_elf_append_rela at bfd/elflink.c:15683 (2.47:15623); unsanitized GNU ld
2.42 asserts and segfaults, while the same IFUNC defined in .text links
cleanly.

Expected result
===============

GNU ld should either produce the correct output or reject the input with a
normal diagnostic. It should not crash, hang, execute undefined behavior, read
outside an input-derived allocation, or produce the described malformed
output.

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