REJECTED/Cmnt: [SRU][Focal][PATCH 0/1] DRBG initialization failed on some AMD EPYC series CPU and lead to kernel panic

[Gerald Yang]

Hi Stefan,

Sorry for the late reply and confusion.
I used the wrong word, it was a clean cherry-pick from the upstream commit,
not a backport.
Should I submit a v2 for this?

Thanks,
Gerald

On Fri, Jun 21, 2024 at 10:01 PM Stefan Bader <stefan.bader at canonical.com>
wrote:

> On 18.06.24 14:49, Gerald Yang wrote:
> > BugLink: https://bugs.launchpad.net/bugs/2069715
> >
> > [Impact]
> >
> > Install Focal with FIPS enabled on AMD EPYC 7262 8-Core Processor,
> kernel panic happens during boot:
> > [ 3.430477] ima: Allocated hash algorithm: sha1
> > [ 3.433358] ima: No architecture policies found
> > [ 3.435785] evm: Initialising EVM extended attributes:
> > [ 3.438271] evm: security.selinux
> > [ 3.440265] evm: security.SMACK64
> > [ 3.442532] evm: security.SMACK64EXEC
> > [ 3.444753] evm: security.SMACK64TRANSMUTE
> > [ 3.446900] evm: security.SMACK64MMAP
> > [ 3.448912] evm: security.apparmor
> > [ 3.452277] evm: security.ima
> > [ 3.455549] evm: security.capability
> > [ 3.457537] evm: HMAC attrs: 0x1
> > [ 3.461049] PM: Magic number: 12:438:677
> > [ 3.463502] rtc_cmos 00:03: setting system clock to 2024-06-18T09:40:59
> UTC (1718703659)
> > [ 3.467750] Kernel panic - not syncing: random: Failed to reset DRBG
> (drbg_nopr_ctr_aes256): -2
> > [ 3.471060] CPU: 2 PID: 1 Comm: swapper/0 Not tainted 5.4.0-1100-fips
> #110-Ubuntu
> > [ 3.474288] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009)/LXD, BIOS
> 0.0.0 02/06/2015
> > [ 3.478191] Call Trace:
> > [ 3.480175] dump_stack+0x6d/0x8b
> > [ 3.482652] panic+0x114/0x2f6
> > [ 3.490069] fips_drbg_init+0xa7/0xbd
> > [ 3.492169] ? chr_dev_init+0x148/0x148
> > [ 3.494330] do_one_initcall+0x4a/0x200
> > [ 3.496396] kernel_init_freeable+0x1e6/0x289
> > [ 3.498967] ? rest_init+0xb0/0xb0
> > [ 3.500965] kernel_init+0xe/0x110
> > [ 3.502983] ret_from_fork+0x35/0x40
> > [ 3.505305] Kernel Offset: 0x35c00000 from 0xffffffff81000000
> (relocation range: 0xffffffff80000000-0xffffffffbfffffff)
> > [ 3.509544] ACPI MEMORY or I/O RESET_REG.
> >
> > It fails to initialize DRBG, this issue doesn't happen on Intel CPU,
> only on some AMD EPYC series CPU.
> > Also Jammy with FIPS enabled doesn't have this issue.
> >
> > [Fix]
> >
> > It's been fixed by this upstream commit:
> > commit 552d03a223eda3df84526ab2c1f4d82e15eaee7a
> > Author: Stephan M<C3><BC>ller <smueller at chronox.de>
> > Date: Sun Nov 21 15:14:20 2021 +0100
> >
> >      crypto: jitter - consider 32 LSB for APT
> >
> >      The APT compares the current time stamp with a pre-set value. The
> >      current code only considered the 4 LSB only. Yet, after reviews by
> >      mathematicians of the user space Jitter RNG version >= 3.1.0, it was
> >      concluded that the APT can be calculated on the 32 LSB of the time
> >      delta. Thi change is applied to the kernel.
> >
> >      This fixes a bug where an AMD EPYC fails this test as its RDTSC
> value
> >      contains zeros in the LSB. The most appropriate fix would have been
> to
> >      apply a GCD calculation and divide the time stamp by the GCD. Yet,
> this
> >      is a significant code change that will be considered for a future
> >      update. Note, tests showed that constantly the GCD always was 32 on
> >      these systems, i.e. the 5 LSB were always zero (thus failing the APT
> >      since it only considered the 4 LSB for its calculation).
> >
> >      Signed-off-by: Stephan Mueller <smueller at chronox.de>
> >      Signed-off-by: Herbert Xu <herbert at gondor.apana.org.au>
> >
> > [Testcase]
> >
> > On AMD EPYC 7262 8-Core Processor, create a VM and enable FIPS can also
> reproduce the issue.
> > I backported the upstream commit to Focal FIPS kernel
> (5.4.0-1100.110-fips) for testing, the DRBG init failed message is gone:
>
> You mention here that you *backported* the upstream change to focal but
> the submitted patch is a cherry pick (it also looks like this is the
> case). It does not apply to focal at all.
> Please submit a v2 with the actual backport. Thanks.
>
> -Stefan
>
> > [ 3.267954] rtc_cmos 00:03: setting system clock to 2024-06-18T06:58:53
> UTC (1718693933)
> > [ 3.275683] random: random: DRBG (drbg_nopr_ctr_aes256) initialized!
> > [ 3.279309] md: Waiting for all devices to be available before autodetect
> >
> > [Where problems could occur]
> >
> > This commit considers AMD EPYC CPU's RDTSC contains zero in LSB, this
> won't affect other cases.
> >
> > [Other Info]
> >
> > Users also reported the issue here:
> > https://bugs.launchpad.net/ubuntu/+source/linux/+bug/2045322
> >
> https://askubuntu.com/questions/1509977/fips-kernel-panics-with-failed-to-reset-drbg-during-boot
> >
> > Stephan Müller (1):
> >    crypto: jitter - consider 32 LSB for APT
> >
> >   crypto/jitterentropy.c | 3 +--
> >   1 file changed, 1 insertion(+), 2 deletions(-)
> >
>
> --
> - Stefan
>
>
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