https://sourceware.org/bugzilla/show_bug.cgi?id=34834
Bug ID: 34834
Summary: GNU ld's PDP-11 backend performs null-pointer
arithmetic for a valid stripped object
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 17154
--> https://sourceware.org/bugzilla/attachment.cgi?id=17154&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 BFD-generated a.out-pdp11 object stripped to zero symbols makes current
ASan/UBSan GNU ld abort in aout_link_add_symbols at bfd/pdp11.c:2890 by
evaluating NULL + 0; applying the generic a.out zero-count guard exposes a
second sequential NULL + 0 in aout_link_write_symbols, while the unstripped
control and current plain linker pass.
Reproduction
============
1. Download and extract
`bfd-pdp11-zero-symbol-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_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 BFD-generated a.out-pdp11 object stripped to zero symbols makes current
ASan/UBSan GNU ld abort in aout_link_add_symbols at bfd/pdp11.c:2890 by
evaluating NULL + 0; applying the generic a.out zero-count guard exposes a
second sequential NULL + 0 in aout_link_write_symbols, while the unstripped
control and current plain linker pass.
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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