https://sourceware.org/bugzilla/show_bug.cgi?id=34840
Bug ID: 34840
Summary: GNU ld PPC64 unaligned TLS TOC diagnostic dereferences
a NULL howto entry
Product: binutils
Version: 2.46
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 17160
--> https://sourceware.org/bugzilla/attachment.cgi?id=17160&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 unaligned R_PPC64_DTPMOD64 relocation reaches the PPC64 TLS TOC rejection
path before the lazily initialized HOWTO table has been populated; current
UBSan reports a NULL member access at elf64-ppc.c:5268, current plain and GNU
ld 2.46 SIGSEGV, GNU ld 2.46 Valgrind reports an invalid read at address 0x20,
and the byte-identical aligned-offset control links cleanly.
Reproduction
============
1. Download and extract
`bfd-ppc64-tls-toc-unaligned-null-howto-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:
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 unaligned R_PPC64_DTPMOD64 relocation reaches the PPC64 TLS TOC rejection
path before the lazily initialized HOWTO table has been populated; current
UBSan reports a NULL member access at elf64-ppc.c:5268, current plain and GNU
ld 2.46 SIGSEGV, GNU ld 2.46 Valgrind reports an invalid read at address 0x20,
and the byte-identical aligned-offset 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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