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Filename Latest commit message Latest commit date
Pawan Gupta 0800f1b45b x86/speculation/mmio: Add mitigation for Processor MMIO Stale Data
commit 8cb861e9e3c9a55099ad3d08e1a3b653d29c33ca upstream

Processor MMIO Stale Data is a class of vulnerabilities that may
expose data after an MMIO operation. For details please refer to
Documentation/admin-guide/hw-vuln/processor_mmio_stale_data.rst.

These vulnerabilities are broadly categorized as:

Device Register Partial Write (DRPW):
  Some endpoint MMIO registers incorrectly handle writes that are
  smaller than the register size. Instead of aborting the write or only
  copying the correct subset of bytes (for example, 2 bytes for a 2-byte
  write), more bytes than specified by the write transaction may be
  written to the register. On some processors, this may expose stale
  data from the fill buffers of the core that created the write
  transaction.

Shared Buffers Data Sampling (SBDS):
  After propagators may have moved data around the uncore and copied
  stale data into client core fill buffers, processors affected by MFBDS
  can leak data from the fill buffer.

Shared Buffers Data Read (SBDR):
  It is similar to Shared Buffer Data Sampling (SBDS) except that the
  data is directly read into the architectural software-visible state.

An attacker can use these vulnerabilities to extract data from CPU fill
buffers using MDS and TAA methods. Mitigate it by clearing the CPU fill
buffers using the VERW instruction before returning to a user or a
guest.

On CPUs not affected by MDS and TAA, user application cannot sample data
from CPU fill buffers using MDS or TAA. A guest with MMIO access can
still use DRPW or SBDR to extract data architecturally. Mitigate it with
VERW instruction to clear fill buffers before VMENTER for MMIO capable
guests.

Add a kernel parameter mmio_stale_data={off|full|full,nosmt} to control
the mitigation.

Signed-off-by: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-06-16 13:23:31 +02:00
arch x86/speculation/mmio: Add mitigation for Processor MMIO Stale Data 2022-06-16 13:23:31 +02:00
block block: fix bio_clone_blkg_association() to associate with proper blkcg_gq 2022-06-14 18:11:50 +02:00
certs certs: Trigger creation of RSA module signing key if it's not an RSA key 2021-09-15 09:47:29 +02:00
crypto crypto: cryptd - Protect per-CPU resource by disabling BH. 2022-06-14 18:11:41 +02:00
Documentation x86/speculation/mmio: Add mitigation for Processor MMIO Stale Data 2022-06-16 13:23:31 +02:00
drivers mtd: cfi_cmdset_0002: Use chip_ready() for write on S29GL064N 2022-06-14 18:12:03 +02:00
fs cifs: return errors during session setup during reconnects 2022-06-14 18:12:02 +02:00
include cpu/speculation: Add prototype for cpu_show_srbds() 2022-06-16 13:23:31 +02:00
init Kconfig: add config option for asm goto w/ outputs 2022-06-14 18:11:50 +02:00
ipc ipc/mqueue: use get_tree_nodev() in mqueue_get_tree() 2022-06-14 18:11:41 +02:00
kernel tracing: Avoid adding tracer option before update_tracer_options 2022-06-14 18:11:56 +02:00
lib nodemask: Fix return values to be unsigned 2022-06-14 18:12:02 +02:00
LICENSES
mm hugetlb: fix huge_pmd_unshare address update 2022-06-14 18:11:48 +02:00
net tcp: fix tcp_mtup_probe_success vs wrong snd_cwnd 2022-06-14 18:12:03 +02:00
samples samples/kretprobes: Fix return value if register_kretprobe() failed 2021-11-17 09:48:39 +01:00
scripts scripts/gdb: change kernel config dumping method 2022-06-14 18:12:02 +02:00
security efi: Do not import certificates from UEFI Secure Boot for T2 Macs 2022-06-14 18:11:44 +02:00
sound ALSA: hda/conexant - Fix loopback issue with CX20632 2022-06-14 18:12:02 +02:00
tools netfilter: nat: really support inet nat without l3 address 2022-06-14 18:11:57 +02:00
usr
virt KVM: Prevent module exit until all VMs are freed 2022-04-15 14:18:27 +02:00
.clang-format
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore
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COPYING
CREDITS
Kbuild
Kconfig
MAINTAINERS
Makefile Linux 5.4.198 2022-06-14 18:12:03 +02:00
README

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.