linux-stable.git/arch/x86/kernel, branch linux-4.9.y

uprobes/x86: Allow to probe a NOP instruction with 0x66 prefix

2023-01-07T11:07:15+00:00

[ Upstream commit cefa72129e45313655d53a065b8055aaeb01a0c9 ]

Intel ICC -hotpatch inserts 2-byte "0x66 0x90" NOP at the start of each
function to reserve extra space for hot-patching, and currently it is not
possible to probe these functions because branch_setup_xol_ops() wrongly
rejects NOP with REP prefix as it treats them like word-sized branch
instructions.

Fixes: 250bbd12c2fe ("uprobes/x86: Refuse to attach uprobe to "word-sized" branch insns")
Reported-by: Seiji Nishikawa 
Suggested-by: Denys Vlasenko 
Signed-off-by: Oleg Nesterov 
Signed-off-by: Thomas Gleixner 
Acked-by: Masami Hiramatsu (Google) 
Link: https://lore.kernel.org/r/20221204173933.GA31544@redhat.com
Signed-off-by: Sasha Levin

x86/tsx: Add a feature bit for TSX control MSR support

2022-12-08T10:15:42+00:00

commit aaa65d17eec372c6a9756833f3964ba05b05ea14 upstream.

Support for the TSX control MSR is enumerated in MSR_IA32_ARCH_CAPABILITIES.
This is different from how other CPU features are enumerated i.e. via
CPUID. Currently, a call to tsx_ctrl_is_supported() is required for
enumerating the feature. In the absence of a feature bit for TSX control,
any code that relies on checking feature bits directly will not work.

In preparation for adding a feature bit check in MSR save/restore
during suspend/resume, set a new feature bit X86_FEATURE_TSX_CTRL when
MSR_IA32_TSX_CTRL is present.

  [ bp: Remove tsx_ctrl_is_supported()]

  [Pawan: Resolved conflicts in backport; Removed parts of commit message
          referring to removed function tsx_ctrl_is_supported()]

Suggested-by: Andrew Cooper 
Signed-off-by: Pawan Gupta 
Signed-off-by: Borislav Petkov 
Reviewed-by: Dave Hansen 
Cc: 
Link: https://lore.kernel.org/r/de619764e1d98afbb7a5fa58424f1278ede37b45.1668539735.git.pawan.kumar.gupta@linux.intel.com
Signed-off-by: Greg Kroah-Hartman

x86/cpu: Restore AMD's DE_CFG MSR after resume

2022-11-25T16:35:38+00:00

commit 2632daebafd04746b4b96c2f26a6021bc38f6209 upstream.

DE_CFG contains the LFENCE serializing bit, restore it on resume too.
This is relevant to older families due to the way how they do S3.

Unify and correct naming while at it.

Fixes: e4d0e84e4907 ("x86/cpu/AMD: Make LFENCE a serializing instruction")
Reported-by: Andrew Cooper 
Reported-by: Pawan Gupta 
Signed-off-by: Borislav Petkov 
Cc: 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

x86/bugs: Add "unknown" reporting for MMIO Stale Data

2022-09-05T08:23:56+00:00

commit 7df548840c496b0141fb2404b889c346380c2b22 upstream.

Older Intel CPUs that are not in the affected processor list for MMIO
Stale Data vulnerabilities currently report "Not affected" in sysfs,
which may not be correct. Vulnerability status for these older CPUs is
unknown.

Add known-not-affected CPUs to the whitelist. Report "unknown"
mitigation status for CPUs that are not in blacklist, whitelist and also
don't enumerate MSR ARCH_CAPABILITIES bits that reflect hardware
immunity to MMIO Stale Data vulnerabilities.

Mitigation is not deployed when the status is unknown.

  [ bp: Massage, fixup. ]

Fixes: 8d50cdf8b834 ("x86/speculation/mmio: Add sysfs reporting for Processor MMIO Stale Data")
Suggested-by: Andrew Cooper 
Suggested-by: Tony Luck 
Signed-off-by: Pawan Gupta 
Signed-off-by: Borislav Petkov 
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/a932c154772f2121794a5f2eded1a11013114711.1657846269.git.pawan.kumar.gupta@linux.intel.com
Signed-off-by: Greg Kroah-Hartman

x86: Clear .brk area at early boot

2022-07-21T18:40:32+00:00

[ Upstream commit 38fa5479b41376dc9d7f57e71c83514285a25ca0 ]

The .brk section has the same properties as .bss: it is an alloc-only
section and should be cleared before being used.

Not doing so is especially a problem for Xen PV guests, as the
hypervisor will validate page tables (check for writable page tables
and hypervisor private bits) before accepting them to be used.

Make sure .brk is initially zero by letting clear_bss() clear the brk
area, too.

Signed-off-by: Juergen Gross 
Signed-off-by: Borislav Petkov 
Link: https://lore.kernel.org/r/20220630071441.28576-3-jgross@suse.com
Signed-off-by: Sasha Levin

x86/speculation/mmio: Print SMT warning

2022-06-16T11:00:52+00:00

commit 1dc6ff02c8bf77d71b9b5d11cbc9df77cfb28626 upstream

Similar to MDS and TAA, print a warning if SMT is enabled for the MMIO
Stale Data vulnerability.

Signed-off-by: Josh Poimboeuf 
Signed-off-by: Thomas Gleixner 
Signed-off-by: Thadeu Lima de Souza Cascardo 
Signed-off-by: Greg Kroah-Hartman

x86/speculation/mmio: Reuse SRBDS mitigation for SBDS

2022-06-16T11:00:52+00:00

commit a992b8a4682f119ae035a01b40d4d0665c4a2875 upstream

The Shared Buffers Data Sampling (SBDS) variant of Processor MMIO Stale
Data vulnerabilities may expose RDRAND, RDSEED and SGX EGETKEY data.
Mitigation for this is added by a microcode update.

As some of the implications of SBDS are similar to SRBDS, SRBDS mitigation
infrastructure can be leveraged by SBDS. Set X86_BUG_SRBDS and use SRBDS
mitigation.

Mitigation is enabled by default; use srbds=off to opt-out. Mitigation
status can be checked from below file:

  /sys/devices/system/cpu/vulnerabilities/srbds

Signed-off-by: Pawan Gupta 
Signed-off-by: Borislav Petkov 
Signed-off-by: Thomas Gleixner 
[cascardo: adjust for processor model names]
Signed-off-by: Thadeu Lima de Souza Cascardo 
Signed-off-by: Greg Kroah-Hartman

x86/speculation/srbds: Update SRBDS mitigation selection

2022-06-16T11:00:52+00:00

commit 22cac9c677c95f3ac5c9244f8ca0afdc7c8afb19 upstream

Currently, Linux disables SRBDS mitigation on CPUs not affected by
MDS and have the TSX feature disabled. On such CPUs, secrets cannot
be extracted from CPU fill buffers using MDS or TAA. Without SRBDS
mitigation, Processor MMIO Stale Data vulnerabilities can be used to
extract RDRAND, RDSEED, and EGETKEY data.

Do not disable SRBDS mitigation by default when CPU is also affected by
Processor MMIO Stale Data vulnerabilities.

Signed-off-by: Pawan Gupta 
Signed-off-by: Borislav Petkov 
Signed-off-by: Thomas Gleixner 
Signed-off-by: Thadeu Lima de Souza Cascardo 
Signed-off-by: Greg Kroah-Hartman

x86/speculation/mmio: Add sysfs reporting for Processor MMIO Stale Data

2022-06-16T11:00:52+00:00

commit 8d50cdf8b8341770bc6367bce40c0c1bb0e1d5b3 upstream

Add the sysfs reporting file for Processor MMIO Stale Data
vulnerability. It exposes the vulnerability and mitigation state similar
to the existing files for the other hardware vulnerabilities.

Signed-off-by: Pawan Gupta 
Signed-off-by: Borislav Petkov 
Signed-off-by: Thomas Gleixner 
Signed-off-by: Thadeu Lima de Souza Cascardo 
Signed-off-by: Greg Kroah-Hartman

x86/speculation/mmio: Enable CPU Fill buffer clearing on idle

2022-06-16T11:00:52+00:00

commit 99a83db5a605137424e1efe29dc0573d6a5b6316 upstream

When the CPU is affected by Processor MMIO Stale Data vulnerabilities,
Fill Buffer Stale Data Propagator (FBSDP) can propagate stale data out
of Fill buffer to uncore buffer when CPU goes idle. Stale data can then
be exploited with other variants using MMIO operations.

Mitigate it by clearing the Fill buffer before entering idle state.

Signed-off-by: Pawan Gupta 
Signed-off-by: Thomas Gleixner 
Co-developed-by: Josh Poimboeuf 
Signed-off-by: Josh Poimboeuf 
Signed-off-by: Borislav Petkov 
Signed-off-by: Thomas Gleixner 
Signed-off-by: Thadeu Lima de Souza Cascardo 
Signed-off-by: Greg Kroah-Hartman