https://sourceware.org/bugzilla/show_bug.cgi?id=34860
Bug ID: 34860
Summary: GNU ld reads outside .dynsym for a relocation to an
excluded definition
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 17180
--> https://sourceware.org/bugzilla/attachment.cgi?id=17180&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
=======
An assembler-produced x86-64 ET_REL whose live GOTPCREL reference names a
global in an SHF_EXCLUDE section makes current and released GNU ld read outside
.dynsym in elf_x86_64_reloc_type_class under -shared --emit-relocs; optimized
BFD segfaults, while -z nocombreloc exits zero with symbol index 0xffffffff and
the resulting DSO crashes the tested glibc loaders; the paired non-excluded
control links and loads.
Reproduction
============
1. Download and extract
`bfd-shf-exclude-emit-relocs-symbol-index-oob-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
===============
An assembler-produced x86-64 ET_REL whose live GOTPCREL reference names a
global in an SHF_EXCLUDE section makes current and released GNU ld read outside
.dynsym in elf_x86_64_reloc_type_class under -shared --emit-relocs; optimized
BFD segfaults, while -z nocombreloc exits zero with symbol index 0xffffffff and
the resulting DSO crashes the tested glibc loaders; the paired non-excluded
control links and loads.
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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