x86/srso: Fix vulnerability reporting for missing microcode

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[ Upstream commit dc6306ad5b ]

The SRSO default safe-ret mitigation is reported as "mitigated" even if
microcode hasn't been updated.  That's wrong because userspace may still
be vulnerable to SRSO attacks due to IBPB not flushing branch type
predictions.

Report the safe-ret + !microcode case as vulnerable.

Also report the microcode-only case as vulnerable as it leaves the
kernel open to attacks.

Fixes: fb3bd914b3 ("x86/srso: Add a Speculative RAS Overflow mitigation")
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Acked-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/a8a14f97d1b0e03ec255c81637afdf4cf0ae9c99.1693889988.git.jpoimboe@kernel.org
Signed-off-by: Sasha Levin <sashal@kernel.org>

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This commit is contained in:

Josh Poimboeuf 2023-09-04 22:04:52 -07:00 • committed by Greg Kroah-Hartman

parent 5b66cf0762

commit 0a958abffa

2 changed files with 39 additions and 21 deletions

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24

Documentation/admin-guide/hw-vuln/srso.rst

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36

arch/x86/kernel/cpu/bugs.c

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