https://sourceware.org/bugzilla/show_bug.cgi?id=34803
Bug ID: 34803
Summary: GNU ld dereferences a null relocation section for a
GNU_MBIND start symbol
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 17123
--> https://sourceware.org/bugzilla/attachment.cgi?id=17123&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 valid GNU-as x86-64 ET_REL with a GOTPCREL reference to synthesized
__start_data and an SHF_GNU_MBIND data section makes current and released GNU
ld reach a null sreloc in elf_x86_allocate_dynrelocs at bfd/elfxx-x86.c:553;
optimized current BFD and stock BFD 2.42 segfault, while the one-bit non-MBIND
control links cleanly.
Reproduction
============
1. Download and extract
`bfd-gnu-mbind-start-symbol-null-dereference-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 valid GNU-as x86-64 ET_REL with a GOTPCREL reference to synthesized
__start_data and an SHF_GNU_MBIND data section makes current and released GNU
ld reach a null sreloc in elf_x86_allocate_dynrelocs at bfd/elfxx-x86.c:553;
optimized current BFD and stock BFD 2.42 segfault, while the one-bit non-MBIND
control 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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