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Fix make_elf on systems with GNU ld 2.39+ #2141

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Fix make_elf on systems with GNU ld 2.39+ #2141

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clubby789
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Fixes #2140

GNU ld 2.39 introduces a new warning which is always invoked by ELF.from_bytes and similar functions.

This PR detects affected versions of ld and adds an argument which ignores the warning.

@clubby789 clubby789 changed the base branch from dev to stable November 28, 2022 00:16
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Pylint is failing because the existing error (E:585,19: Unexpected keyword argument 'arch' in function call (unexpected-keyword-arg)) has moved down by a few lines.

@clubby789 clubby789 force-pushed the fix-rwx-ld branch 2 times, most recently from d20ec6a to c611be9 Compare November 28, 2022 01:10
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Sorry for the commit/CI spam - I'm not able to reproduce the particular failiure locally

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This appears to be a duplicate of #2098

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Since the author of that PR hasnt responded, I've applied @Diff-fusion's suggestion of checking the return code of ld --no-warn-rwx-segments --help - it looks like many distros releases of ld have differently formatted version strings, and parsing them is probably going to be flaky.

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Nice, this looks more robust now. The same ld version introduced a warning about executable stacks too, so maybe adding --no-warn-execstack is in order like the other PR does?

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I didn't include that one here, as the release notes specify that the warning will not be issued if an executable stack is specifically requested (-z execstack), which is used here. Detecting it introduces another point of failure/delay while that argument is checked.

We could add it unconditionally, but it's possible (while unlikely) some distros will compile with one flag but not the other.

@clubby789 clubby789 mentioned this pull request Nov 28, 2022
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@heapcrash heapcrash mentioned this pull request Dec 4, 2022
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heapcrash
heapcrash requested changes Dec 4, 2022
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pwnlib/asm.py
# https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;a=blob_plain;f=ld/NEWS;hb=refs/heads/binutils-2_39-branch
proc = subprocess.run(ld + ["--no-warn-rwx-segments", "--help"], capture_output=True)
if proc.returncode == 0:
arguments.append("--no-warn-rwx-segments")
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Please see the recommendation in #2140

@github-actions github-actions bot closed this in b8fad78 Dec 28, 2022
gogo2464 pushed a commit to gogo2464/pwntools that referenced this pull request Sep 10, 2023
@Arusekk
Fix binutils version checking and RWX warnings
a856b2d 
Fixes Gallopsled#2140
Closes Gallopsled#2098
Closes Gallopsled#2141
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ELF.from_bytes always throws exception (ld warning treated as error)
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@clubby789 @peace-maker @heapcrash