Module kobj hash is different alert on Linux 5.10.5+ and 5.4.87+ about lkrg HOT 15 CLOSED

Thank you for reporting this and for your analysis, @0xC0ncord. We're trying to get this fixed upstream: https://lists.openwall.net/linux-kernel/2021/01/10/241

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@vt-alt you don't need to load any other module after LKRG. If you load LKRG and trigger integrity routine (sysctl lkrg.trigger=1) you should be able to see this issue.

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@vt-alt Adam's reply was specifically to the question about triggering this issue. To have a higher likelihood of detecting potential future issues like this (not exactly this same issue), I think loading another module after LKRG in the integration test is a good idea.

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A quick glance at the history for 5.10.5 leads me to believe that this commit is somehow involved.

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A quick glance at the history for 5.10.5 leads me to believe that this commit is somehow involved.

I was able to confirm that this is causing the issue. I was able to workaround it for now by reversing this commit on my local kernel build, but this is certainly an issue that needs to be worked around in LKRG now.

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We got a NAK from Greg KH (not a stable API, no support for out-of-tree kernel code, the new code is correct as-is as far as the kernel is concerned), so Adam now intends to work this issue around in LKRG itself. I think that's fine.

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Fixed by the following commit:
8814ebe

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FWIW, the kernel change problematic for older LKRG was back-ported to 5.4.87+, so recent LKRG containing Adam's commit referenced above is required for those kernel versions as well.

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I've just updated the LKRG homepage to say:

"LKRG 0.8.1 supports Linux kernels up to and including 5.7.x, which were the latest at the time of this LKRG release. For Linux 5.8+ or stable 5.4.87+ (which was released after LKRG 0.8.1 and includes some back-ports from Linux 5.8+), a newer LKRG revision off GitHub is required (and we recommend that you use the latest)."

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We want to add a small integration test (in qemu) in ALT for similar cases. How to manually trigger this issue? Just load any other module after p_lkrg is loaded? @wladmis

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@Adam-pi3 Thanks much!

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Using 5.14.0-4-amd64 #1 SMP Debian 5.14.16-1 (2021-11-03) x86_64 GNU/Linux and LKRG 0.9.1-5 from https://deb.whonix.org, spurious MODULE KOBJ HASH IS DIFFERENT log messages are still an issue

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@Emm No, in our understanding it's not "still", but "again" - a different issue that manifests itself the same on 5.14+. We tracked that new issue as #117 and we believe we've fixed it in a9906a6. I guess the Whonix package doesn't have that new fix yet, @adrelanos.

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Indeed. Waiting for next stable release of LKRG and also some sort of signed git commits or git tags would be very helpful. (#67)

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@solardiz , thanks for the prompt answer.

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