affdbc8fbc
commit 5bcedc5931e7bd6928a2d8207078d4cb476b3b55 upstream.
Nageswara reported that /proc/self/status was showing "vulnerable" for
the Speculation_Store_Bypass feature on Power10, eg:
$ grep Speculation_Store_Bypass: /proc/self/status
Speculation_Store_Bypass: vulnerable
But at the same time the sysfs files, and lscpu, were showing "Not
affected".
This turns out to simply be a bug in the reporting of the
Speculation_Store_Bypass, aka. PR_SPEC_STORE_BYPASS, case.
When SEC_FTR_STF_BARRIER was added, so that firmware could communicate
the vulnerability was not present, the code in ssb_prctl_get() was not
updated to check the new flag.
So add the check for SEC_FTR_STF_BARRIER being disabled. Rather than
adding the new check to the existing if block and expanding the comment
to cover both cases, rewrite the three cases to be separate so they can
be commented separately for clarity.
Fixes: 84ed26fd00c5 ("powerpc/security: Add a security feature for STF barrier")
Cc: stable@vger.kernel.org # v5.14+
Reported-by: Nageswara R Sastry <rnsastry@linux.ibm.com>
Tested-by: Nageswara R Sastry <rnsastry@linux.ibm.com>
Reviewed-by: Russell Currey <ruscur@russell.cc>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20230517074945.53188-1-mpe@ellerman.id.au
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.