https://sourceware.org/bugzilla/show_bug.cgi?id=34801
Bug ID: 34801
Summary: GNU ld materializes an entire section-alignment gap in
one fill buffer
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 17121
--> https://sourceware.org/bugzilla/attachment.cgi?id=17121&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
=======
Tiny valid x86-64 ET_REL inputs with two merged executable sections and 2^32 or
2^35 alignment make GNU ld allocate the entire intervening NOP-fill gap in one
4 GiB or 32 GiB buffer in bfd_arch_i386_fill; current, official 2.47, and
system 2.42 builds reproduce under strict allocation or address-space limits,
while an alignment-16 control links cleanly. A separately isolated 712-byte
LoongArch64 artifact reaches the same _bfd_default_link_order root through
bfd_arch_default_fill: sh_addralign 2^32 requests 0xfffffff8 bytes, while its
alignment-1 control links cleanly.
Reproduction
============
1. Download and extract
`bfd-executable-alignment-nop-fill-memory-dos-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
===============
Tiny valid x86-64 ET_REL inputs with two merged executable sections and 2^32 or
2^35 alignment make GNU ld allocate the entire intervening NOP-fill gap in one
4 GiB or 32 GiB buffer in bfd_arch_i386_fill; current, official 2.47, and
system 2.42 builds reproduce under strict allocation or address-space limits,
while an alignment-16 control links cleanly. A separately isolated 712-byte
LoongArch64 artifact reaches the same _bfd_default_link_order root through
bfd_arch_default_fill: sh_addralign 2^32 requests 0xfffffff8 bytes, while its
alignment-1 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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