linux-stable.git/Documentation, branch v5.4.264

firmware: ti_sci: Replace HTTP links with HTTPS ones

2023-11-20T09:30:12+00:00

[ Upstream commit a6df49f4224324dd8588f6a0d9cff53cd61a196b ]

Rationale:
Reduces attack surface on kernel devs opening the links for MITM
as HTTPS traffic is much harder to manipulate.

Deterministic algorithm:
For each file:
  If not .svg:
    For each line:
      If doesn't contain `\bxmlns\b`:
        For each link, `\bhttp://[^# \t\r\n]*(?:\w|/)`:
	  If neither `\bgnu\.org/license`, nor `\bmozilla\.org/MPL\b`:
            If both the HTTP and HTTPS versions
            return 200 OK and serve the same content:
              Replace HTTP with HTTPS.

Signed-off-by: Alexander A. Klimov 
Acked-by: Rob Herring 
Signed-off-by: Santosh Shilimkar 
Stable-dep-of: 7b7a224b1ba1 ("firmware: ti_sci: Mark driver as non removable")
Signed-off-by: Sasha Levin

Documentation: sysctl: align cells in second content column

2023-10-25T09:53:20+00:00

commit 1faa34672f8a17a3e155e74bde9648564e9480d6 upstream.

Stephen Rothwell reported htmldocs warning when merging net-next tree:

Documentation/admin-guide/sysctl/net.rst:37: WARNING: Malformed table.
Text in column margin in table line 4.

========= =================== = ========== ==================
Directory Content               Directory  Content
========= =================== = ========== ==================
802       E802 protocol         mptcp     Multipath TCP
appletalk Appletalk protocol    netfilter Network Filter
ax25      AX25                  netrom     NET/ROM
bridge    Bridging              rose      X.25 PLP layer
core      General parameter     tipc      TIPC
ethernet  Ethernet protocol     unix      Unix domain sockets
ipv4      IP version 4          x25       X.25 protocol
ipv6      IP version 6
========= =================== = ========== ==================

The warning above is caused by cells in second "Content" column of
/proc/sys/net subdirectory table which are in column margin.

Align these cells against the column header to fix the warning.

Link: https://lore.kernel.org/linux-next/20220823134905.57ed08d5@canb.auug.org.au/
Fixes: 1202cdd665315c ("Remove DECnet support from kernel")
Reported-by: Stephen Rothwell 
Signed-off-by: Bagas Sanjaya 
Link: https://lore.kernel.org/r/20220824035804.204322-1-bagasdotme@gmail.com
Signed-off-by: Jakub Kicinski 
Cc: Ben Hutchings 
Signed-off-by: Greg Kroah-Hartman

perf/smmuv3: Enable HiSilicon Erratum 162001900 quirk for HIP08/09

2023-09-23T09:00:03+00:00

[ Upstream commit 0242737dc4eb9f6e9a5ea594b3f93efa0b12f28d ]

Some HiSilicon SMMU PMCG suffers the erratum 162001900 that the PMU
disable control sometimes fail to disable the counters. This will lead
to error or inaccurate data since before we enable the counters the
counter's still counting for the event used in last perf session.

This patch tries to fix this by hardening the global disable process.
Before disable the PMU, writing an invalid event type (0xffff) to
focibly stop the counters. Correspondingly restore each events on
pmu::pmu_enable().

Signed-off-by: Yicong Yang 
Link: https://lore.kernel.org/r/20230814124012.58013-1-yangyicong@huawei.com
Signed-off-by: Will Deacon 
Signed-off-by: Sasha Levin

Documentation/sysctl: document page_lock_unfairness

2023-08-30T14:27:27+00:00

commit 8d98e42fb20c25e8efdab4cc1ac46d52ba964aca upstream.

commit 5ef64cc8987a ("mm: allow a controlled amount of unfairness in the
page lock") introduced a new systctl but no accompanying documentation.

Add a simple entry to the documentation.

Link: https://lkml.kernel.org/r/20220325164437.120246-1-jsavitz@redhat.com
Signed-off-by: Joel Savitz 
Cc: Jonathan Corbet 
Cc: Vlastimil Babka 
Cc: Mel Gorman 
Cc: Dave Hansen 
Cc: Suren Baghdasaryan 
Cc: Mike Rapoport 
Cc: "zhangyi (F)" 
Cc: Charan Teja Reddy 
Cc: Linus Torvalds 
Signed-off-by: Andrew Morton 
Signed-off-by: Greg Kroah-Hartman

PM: runtime: Add pm_runtime_get_if_active()

2023-08-30T14:27:12+00:00

[ Upstream commit c111566bea7ccd8a05e2c56f1fb3cbb6f4b7b441 ]

pm_runtime_get_if_in_use() bumps up the PM-runtime usage count if it
is not equal to zero and the device's PM-runtime status is 'active'.
This works for drivers that do not use autoidle, but for those that
do, the function returns zero even when the device is active.

In order to maintain sane device state while the device is powered on
in the hope that it'll be needed, pm_runtime_get_if_active(dev, true)
returns a positive value if the device's PM-runtime status is 'active'
when it is called, in which case it also increments the device's usage
count.

If the second argument of pm_runtime_get_if_active() is 'false', the
function behaves just like pm_runtime_get_if_in_use(), so redefine
the latter as a wrapper around the former.

Signed-off-by: Sakari Ailus 
[ rjw: Changelog ]
Signed-off-by: Rafael J. Wysocki 
Stable-dep-of: 81302b1c7c99 ("ALSA: hda: Fix unhandled register update during auto-suspend period")
Signed-off-by: Sasha Levin

Documentation: security-bugs.rst: clarify CVE handling

2023-08-11T09:53:52+00:00

commit 3c1897ae4b6bc7cc586eda2feaa2cd68325ec29c upstream.

The kernel security team does NOT assign CVEs, so document that properly
and provide the "if you want one, ask MITRE for it" response that we
give on a weekly basis in the document, so we don't have to constantly
say it to everyone who asks.

Link: https://lore.kernel.org/r/2023063022-retouch-kerosene-7e4a@gregkh
Signed-off-by: Greg Kroah-Hartman

Documentation: security-bugs.rst: update preferences when dealing with the linux-distros group

2023-08-11T09:53:51+00:00

commit 4fee0915e649bd0cea56dece6d96f8f4643df33c upstream.

Because the linux-distros group forces reporters to release information
about reported bugs, and they impose arbitrary deadlines in having those
bugs fixed despite not actually being kernel developers, the kernel
security team recommends not interacting with them at all as this just
causes confusion and the early-release of reported security problems.

Reviewed-by: Kees Cook 
Link: https://lore.kernel.org/r/2023063020-throat-pantyhose-f110@gregkh
Signed-off-by: Greg Kroah-Hartman

Documentation/x86: Fix backwards on/off logic about YMM support

2023-08-08T17:56:36+00:00

commit 1b0fc0345f2852ffe54fb9ae0e12e2ee69ad6a20 upstream

These options clearly turn *off* XSAVE YMM support.  Correct the
typo.

Reported-by: Ben Hutchings 
Fixes: 553a5c03e90a ("x86/speculation: Add force option to GDS mitigation")
Signed-off-by: Dave Hansen 
Signed-off-by: Greg Kroah-Hartman

x86/speculation: Add force option to GDS mitigation

2023-08-08T17:56:35+00:00

commit 553a5c03e90a6087e88f8ff878335ef0621536fb upstream

The Gather Data Sampling (GDS) vulnerability allows malicious software
to infer stale data previously stored in vector registers. This may
include sensitive data such as cryptographic keys. GDS is mitigated in
microcode, and systems with up-to-date microcode are protected by
default. However, any affected system that is running with older
microcode will still be vulnerable to GDS attacks.

Since the gather instructions used by the attacker are part of the
AVX2 and AVX512 extensions, disabling these extensions prevents gather
instructions from being executed, thereby mitigating the system from
GDS. Disabling AVX2 is sufficient, but we don't have the granularity
to do this. The XCR0[2] disables AVX, with no option to just disable
AVX2.

Add a kernel parameter gather_data_sampling=force that will enable the
microcode mitigation if available, otherwise it will disable AVX on
affected systems.

This option will be ignored if cmdline mitigations=off.

This is a *big* hammer.  It is known to break buggy userspace that
uses incomplete, buggy AVX enumeration.  Unfortunately, such userspace
does exist in the wild:

	https://www.mail-archive.com/bug-coreutils@gnu.org/msg33046.html

[ dhansen: add some more ominous warnings about disabling AVX ]

Signed-off-by: Daniel Sneddon 
Signed-off-by: Dave Hansen 
Acked-by: Josh Poimboeuf 
Signed-off-by: Daniel Sneddon 
Signed-off-by: Greg Kroah-Hartman

x86/speculation: Add Gather Data Sampling mitigation

2023-08-08T17:56:35+00:00

commit 8974eb588283b7d44a7c91fa09fcbaf380339f3a upstream

Gather Data Sampling (GDS) is a hardware vulnerability which allows
unprivileged speculative access to data which was previously stored in
vector registers.

Intel processors that support AVX2 and AVX512 have gather instructions
that fetch non-contiguous data elements from memory. On vulnerable
hardware, when a gather instruction is transiently executed and
encounters a fault, stale data from architectural or internal vector
registers may get transiently stored to the destination vector
register allowing an attacker to infer the stale data using typical
side channel techniques like cache timing attacks.

This mitigation is different from many earlier ones for two reasons.
First, it is enabled by default and a bit must be set to *DISABLE* it.
This is the opposite of normal mitigation polarity. This means GDS can
be mitigated simply by updating microcode and leaving the new control
bit alone.

Second, GDS has a "lock" bit. This lock bit is there because the
mitigation affects the hardware security features KeyLocker and SGX.
It needs to be enabled and *STAY* enabled for these features to be
mitigated against GDS.

The mitigation is enabled in the microcode by default. Disable it by
setting gather_data_sampling=off or by disabling all mitigations with
mitigations=off. The mitigation status can be checked by reading:

    /sys/devices/system/cpu/vulnerabilities/gather_data_sampling

Signed-off-by: Daniel Sneddon 
Signed-off-by: Dave Hansen 
Acked-by: Josh Poimboeuf 
Signed-off-by: Daniel Sneddon 
Signed-off-by: Greg Kroah-Hartman