https://sourceware.org/bugzilla/show_bug.cgi?id=34817
Bug ID: 34817
Summary: GNU ld O32 microMIPS HI16/LO16 relaxation reads past
the relocation array
Product: binutils
Version: 2.48 (HEAD)
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 17137
--> https://sourceware.org/bugzilla/attachment.cgi?id=17137&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
=======
GNU ld --relax on a well-formed two-entry O32 microMIPS HI16/LO16 pair
evaluates irel[2] when irel + 2 equals the relocation-array end because the
bound at elfxx-mips.c:14295 is reversed; current ASan reports a
heap-buffer-overflow READ of size 8 at line 14296 for both big- and
little-endian objects, while the identical objects link cleanly with
--no-relax.
Reproduction
============
1. Download and extract
`bfd-mips-o32-micromips-hi-lo-reloc-array-oob-read-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
===============
GNU ld --relax on a well-formed two-entry O32 microMIPS HI16/LO16 pair
evaluates irel[2] when irel + 2 equals the relocation-array end because the
bound at elfxx-mips.c:14295 is reversed; current ASan reports a
heap-buffer-overflow READ of size 8 at line 14296 for both big- and
little-endian objects, while the identical objects link cleanly with
--no-relax.
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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