https://sourceware.org/bugzilla/show_bug.cgi?id=34788
Bug ID: 34788
Summary: GNU ld AVR relaxation performs null-pointer arithmetic
in two helpers
Product: binutils
Version: 2.46
Status: UNCONFIRMED
Severity: critical
Priority: P2
Component: ld
Assignee: unassigned at sourceware dot org
Reporter: basavesh.shivakumar at wsu dot edu
Target Milestone: ---
Created attachment 17108
--> https://sourceware.org/bugzilla/attachment.cgi?id=17108&action=edit
reproducer
I'm reporting this bug on behalf of my team: Emily West, Dr. Swarn Priya, Dr.
Peng Gao and Dr. Basavesh Ammanaghatta Shivakumar.
Summary
=======
Two valid AVR relaxation objects make the tested fail-fast UBSan build perform
pointer arithmetic on null symbol or relocation arrays in avr_local_label_at
and avr_reloc_at; neutral and same-bytes no-relax controls are clean, and no
invalid memory access is claimed.
Reproduction
============
1. Download and extract
`bfd-avr-relax-null-pointer-arithmetic-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=/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
===============
Two valid AVR relaxation objects make the tested fail-fast UBSan build perform
pointer arithmetic on null symbol or relocation arrays in avr_local_label_at
and avr_reloc_at; neutral and same-bytes no-relax controls are clean, and no
invalid memory access is claimed.
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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