openwall / openwall/john

wpapcap2john illegal instruction (AVX)

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bug portability
Dominant language
C
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Description

While at #4243 , I found that wpapcap2john is not working properly; it has the AVX `vmovdqa.
Be aware that it is a package with a fallback chain of JtR binaries.

  • When I run wpapcap2john -v it works.
  • But it gives me an illegal instruction when I run it using a valid file.

As an example, after disassembling:

    5e4d:	48 89 05 54 6d 20 00 	mov    %rax,0x206d54(%rip)        # 20cba8 <new_p>
    5e54:	0f 84 ac 1b 00 00    	je     7a06 <process_packet+0x2086>
    5e5a:	4c 89 3d 3f 6d 20 00 	mov    %r15,0x206d3f(%rip)        # 20cba0 <new_p_sz>
    5e61:	c5 f9 6f 05 b7 61 20 	vmovdqa 0x2061b7(%rip),%xmm0        # 20c020 <fake802_11>
    5e68:	00 
    5e69:	49 8d 7d 20          	lea    0x20(%r13),%rdi
    5e6d:	48 8d 73 0c          	lea    0xc(%rbx),%rsi
    5e71:	c4 c1 78 11 45 00    	vmovups %xmm0,0x0(%r13)
    5e77:	c5 f9 6f 0d b1 61 20 	vmovdqa 0x2061b1(%rip),%xmm1        # 20c030 <fake802_11+0x10>


zip2john works fine

Contributor guide

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First steps

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  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start by reproducing wpapcap2john -v and then running it with a valid input file, comparing that behavior with zip2john. Inspect the fallback chain of JtR binaries and the reported vmovdqa instruction; done means valid input is processed without an illegal-instruction failure on CPUs lacking AVX.

Written by the indexing model from the issue text.

Assessment

Tech stack
c
Domain
cli
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
35/100

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