Can I restore an edited snapshot without "VERR_SSM_INTEGRITY_REC_TERM_CRC" error?

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james221
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Joined: 29. Jun 2021, 11:56

Can I restore an edited snapshot without "VERR_SSM_INTEGRITY_REC_TERM_CRC" error?

Post by james221 »

Can I restore an edited snapshot without "VERR_SSM_INTEGRITY_REC_TERM_CRC" error?

I edited a snapshot file, when I attempt to restore it, I got an error.

Code: Select all

Failed to load unit 'pgm' (VERR_SSM_INTEGRITY_REC_TERM_CRC).


Result Code: 
E_FAIL (0x80004005)
Component: 
ConsoleWrap
Interface: 
IConsole {872da645-4a9b-1727-bee2-5585105b9eed}

Is there a way to disable the integrity check?

Thanks
fth0
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Re: Can I restore an edited snapshot without "VERR_SSM_INTEGRITY_REC_TERM_CRC" error?

Post by fth0 »

james221 wrote:Is there a way to disable the integrity check?
Not that I'm aware of.

What did you edit in a snapshot file?
mpack
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Re: Can I restore an edited snapshot without "VERR_SSM_INTEGRITY_REC_TERM_CRC" error?

Post by mpack »

Snapshot?

I think you'll find that SSM errors refer to problems in .sav (saved state) files. There is no CRC checking in a snapshot.

SAV files are not intended to be editable.
james221
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Joined: 29. Jun 2021, 11:56

Re: Can I restore an edited snapshot without "VERR_SSM_INTEGRITY_REC_TERM_CRC" error?

Post by james221 »

fth0 wrote:
james221 wrote:Is there a way to disable the integrity check?
Not that I'm aware of.

What did you edit in a snapshot file?
I'm trying to modify a string in a ramfs, which is found it in the ".sav" file, and I was replacing it with a string of the same length.
james221
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Joined: 29. Jun 2021, 11:56

Re: Can I restore an edited snapshot without "VERR_SSM_INTEGRITY_REC_TERM_CRC" error?

Post by james221 »

mpack wrote:Snapshot?

I think you'll find that SSM errors refer to problems in .sav (saved state) files. There is no CRC checking in a snapshot.

SAV files are not intended to be editable.
Is there other way to edit ram? I could use "VBoxManage debugvm" to dump ram, but didn't find a way to recovery.
fth0
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Re: Can I restore an edited snapshot without "VERR_SSM_INTEGRITY_REC_TERM_CRC" error?

Post by fth0 »

If you'd tell us what you really want to achieve, we may come up with other ideas ...
scottgus1
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Re: Can I restore an edited snapshot without "VERR_SSM_INTEGRITY_REC_TERM_CRC" error?

Post by scottgus1 »

james221 wrote:I was replacing it with a string of the same length.
A string of the same length is not necessarily of the same data. Length doesn't matter, the CRC result matters. Just try changing a single character in a string, then compare a new CRC with a CRC before the change:

The quick brown fox jumps over the lazy dog. < CRC32: 519025E9
The quick brown fox Jumps over the lazy dog. < CRC32: AF46DB93

The single capitalized "J" kils the CRC.

You need to make a new CRC after the edit and shoehorn that result in place of the old result too.

This is all theoretical, untried by me. I do not know the CRC type used by Virtualbox. Expect unusable results, make backup copies if the data is important.
james221
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Joined: 29. Jun 2021, 11:56

Re: Can I restore an edited snapshot without "VERR_SSM_INTEGRITY_REC_TERM_CRC" error?

Post by james221 »

scottgus1 wrote:
james221 wrote:I was replacing it with a string of the same length.
A string of the same length is not necessarily of the same data. Length doesn't matter, the CRC result matters. Just try changing a single character in a string, then compare a new CRC with a CRC before the change:

The quick brown fox jumps over the lazy dog. < CRC32: 519025E9
The quick brown fox Jumps over the lazy dog. < CRC32: AF46DB93

The single capitalized "J" kils the CRC.

You need to make a new CRC after the edit and shoehorn that result in place of the old result too.

This is all theoretical, untried by me. I do not know the CRC type used by Virtualbox. Expect unusable results, make backup copies if the data is important.
Yes, I know I have to recalculate the CRC value, but I have no idea about the structure of the .sav file.

Now I have found a way to get things done, the Hyper-V.

Hyper-V checkpoint feature doesn't care about the CRC checksum. Even the ram data is a little discontinuity in the file, It works, at least in this case.
james221
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Joined: 29. Jun 2021, 11:56

Re: Can I restore an edited snapshot without "VERR_SSM_INTEGRITY_REC_TERM_CRC" error?

Post by james221 »

fth0 wrote:If you'd tell us what you really want to achieve, we may come up with other ideas ...
Thank you.

There have a ramfs file(initrd) I wanna deep into it, I have no idea how to unpack a ramfs file, but VM may help.

The reason I was trying to edit snapshot file because I want to edit password in the ram to skip security mechanism could allow me to research.

I have achieved, with Hyper-V.
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