Bug#1019855: Fwd: libc6: immediately crashes with SIGILL on 4th gen Intel Core CPUs (seems related to AVX2 instructions), bricking the whole system
- To: 1019855@bugs.debian.org
- Cc: debian-bug-report@p0358.net
- Subject: Bug#1019855: Fwd: libc6: immediately crashes with SIGILL on 4th gen Intel Core CPUs (seems related to AVX2 instructions), bricking the whole system
- From: Aurelien Jarno <aurel32@debian.org>
- Date: Tue, 4 Oct 2022 08:51:51 +0200
- Message-id: <[🔎] YzvYBzYqvmXNVmyW@aurel32.net>
- Reply-to: Aurelien Jarno <aurel32@debian.org>, 1019855@bugs.debian.org
- In-reply-to: <YzA+8HeR57bI0TXk@aurel32.net>
- References: <bec7fa36-d598-a337-b2a4-0dc67d82876d@p0358.cf> <f5271a8e-fff5-1502-4729-ecdb4b16b27e@p0358.cf> <YyOBlbPVVo/QvAAc@aurel32.net> <YyoumqJrDr0/T3cU@aurel32.net> <f5271a8e-fff5-1502-4729-ecdb4b16b27e@p0358.cf> <2ece07fe-1994-3a70-8359-4d4fcee728c2@p0358.cf> <YzAKaOfvXB1HapqV@aurel32.net> <d47bf345-3612-6d29-35c1-17a19b8228bd@p0358.cf> <f5271a8e-fff5-1502-4729-ecdb4b16b27e@p0358.cf> <YzA+8HeR57bI0TXk@aurel32.net> <f5271a8e-fff5-1502-4729-ecdb4b16b27e@p0358.cf>
Hi
On 2022-09-25 13:43, Aurelien Jarno wrote:
> > Running a quick diff against old procinfo reveals that "flags" has the
> > following new entries now:
> >
> > tsc_deadline_timer ssbd ibrs ibpb stibp bmi1 bmi2 md_clear flush_l1d
> >
> > > it looks like that the BMI2
> > > instructions support has been added in a microcode update
> >
> > As such it does appear that indeed this is the case.
>
> Thanks for the confirmation, it seems that the microcode update is also
> useful for security reasons in order to mitigate the speculative
> execution side channel issues (the famous spectre/meltdown).
>
> Neverthless the AVX2 code should not use BMI2 instructions if they are
> not available.
This has been fixed upstream and in the sid package. Next step is to get
it fixed for stable.
Regards
Aurelien
--
Aurelien Jarno GPG: 4096R/1DDD8C9B
aurelien@aurel32.net http://www.aurel32.net
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