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Merge 4.9.202 into android-4.9-q Changes in 4.9.202 kvm: mmu: Don't read PDPTEs when paging is not enabled Bluetooth: hci_ldisc: Postpone HCI_UART_PROTO_READY bit set in hci_uart_set_proto() MIPS: BCM63XX: fix switch core reset on BCM6368 usb: gadget: core: unmap request from DMA only if previously mapped KVM: x86: use Intel speculation bugs and features as derived in generic x86 code x86/msr: Add the IA32_TSX_CTRL MSR x86/cpu: Add a helper function x86_read_arch_cap_msr() x86/cpu: Add a "tsx=" cmdline option with TSX disabled by default x86/speculation/taa: Add mitigation for TSX Async Abort x86/speculation/taa: Add sysfs reporting for TSX Async Abort kvm/x86: Export MDS_NO=0 to guests when TSX is enabled x86/tsx: Add "auto" option to the tsx= cmdline parameter x86/speculation/taa: Add documentation for TSX Async Abort x86/tsx: Add config options to set tsx=on|off|auto x86/speculation/taa: Fix printing of TAA_MSG_SMT on IBRS_ALL CPUs KVM: x86: simplify ept_misconfig KVM: x86: extend usage of RET_MMIO_PF_* constants kvm: Convert kvm_lock to a mutex kvm: x86: Do not release the page inside mmu_set_spte() KVM: x86: make FNAME(fetch) and __direct_map more similar KVM: x86: remove now unneeded hugepage gfn adjustment KVM: x86: change kvm_mmu_page_get_gfn BUG_ON to WARN_ON KVM: x86: Add is_executable_pte() KVM: x86: add tracepoints around __direct_map and FNAME(fetch) KVM: vmx, svm: always run with EFER.NXE=1 when shadow paging is active x86/bugs: Add ITLB_MULTIHIT bug infrastructure cpu/speculation: Uninline and export CPU mitigations helpers kvm: mmu: ITLB_MULTIHIT mitigation kvm: Add helper function for creating VM worker threads kvm: x86: mmu: Recovery of shattered NX large pages Documentation: Add ITLB_MULTIHIT documentation Linux 4.9.202 Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
2019-11-16 11:05:12 +01:00
.. SPDX-License-Identifier: GPL-2.0
TAA - TSX Asynchronous Abort
======================================
TAA is a hardware vulnerability that allows unprivileged speculative access to
data which is available in various CPU internal buffers by using asynchronous
aborts within an Intel TSX transactional region.
Affected processors
-------------------
This vulnerability only affects Intel processors that support Intel
Transactional Synchronization Extensions (TSX) when the TAA_NO bit (bit 8)
is 0 in the IA32_ARCH_CAPABILITIES MSR. On processors where the MDS_NO bit
(bit 5) is 0 in the IA32_ARCH_CAPABILITIES MSR, the existing MDS mitigations
also mitigate against TAA.
Whether a processor is affected or not can be read out from the TAA
vulnerability file in sysfs. See :ref:`tsx_async_abort_sys_info`.
Related CVEs
------------
The following CVE entry is related to this TAA issue:
============== ===== ===================================================
CVE-2019-11135 TAA TSX Asynchronous Abort (TAA) condition on some
microprocessors utilizing speculative execution may
allow an authenticated user to potentially enable
information disclosure via a side channel with
local access.
============== ===== ===================================================
Problem
-------
When performing store, load or L1 refill operations, processors write
data into temporary microarchitectural structures (buffers). The data in
those buffers can be forwarded to load operations as an optimization.
Intel TSX is an extension to the x86 instruction set architecture that adds
hardware transactional memory support to improve performance of multi-threaded
software. TSX lets the processor expose and exploit concurrency hidden in an
application due to dynamically avoiding unnecessary synchronization.
TSX supports atomic memory transactions that are either committed (success) or
aborted. During an abort, operations that happened within the transactional region
are rolled back. An asynchronous abort takes place, among other options, when a
different thread accesses a cache line that is also used within the transactional
region when that access might lead to a data race.
Immediately after an uncompleted asynchronous abort, certain speculatively
executed loads may read data from those internal buffers and pass it to dependent
operations. This can be then used to infer the value via a cache side channel
attack.
Because the buffers are potentially shared between Hyper-Threads cross
Hyper-Thread attacks are possible.
The victim of a malicious actor does not need to make use of TSX. Only the
attacker needs to begin a TSX transaction and raise an asynchronous abort
which in turn potenitally leaks data stored in the buffers.
More detailed technical information is available in the TAA specific x86
architecture section: :ref:`Documentation/x86/tsx_async_abort.rst <tsx_async_abort>`.
Attack scenarios
----------------
Attacks against the TAA vulnerability can be implemented from unprivileged
applications running on hosts or guests.
As for MDS, the attacker has no control over the memory addresses that can
be leaked. Only the victim is responsible for bringing data to the CPU. As
a result, the malicious actor has to sample as much data as possible and
then postprocess it to try to infer any useful information from it.
A potential attacker only has read access to the data. Also, there is no direct
privilege escalation by using this technique.
.. _tsx_async_abort_sys_info:
TAA system information
-----------------------
The Linux kernel provides a sysfs interface to enumerate the current TAA status
of mitigated systems. The relevant sysfs file is:
/sys/devices/system/cpu/vulnerabilities/tsx_async_abort
The possible values in this file are:
.. list-table::
* - 'Vulnerable'
- The CPU is affected by this vulnerability and the microcode and kernel mitigation are not applied.
* - 'Vulnerable: Clear CPU buffers attempted, no microcode'
- The system tries to clear the buffers but the microcode might not support the operation.
* - 'Mitigation: Clear CPU buffers'
- The microcode has been updated to clear the buffers. TSX is still enabled.
* - 'Mitigation: TSX disabled'
- TSX is disabled.
* - 'Not affected'
- The CPU is not affected by this issue.
.. _ucode_needed:
Best effort mitigation mode
^^^^^^^^^^^^^^^^^^^^^^^^^^^
If the processor is vulnerable, but the availability of the microcode-based
mitigation mechanism is not advertised via CPUID the kernel selects a best
effort mitigation mode. This mode invokes the mitigation instructions
without a guarantee that they clear the CPU buffers.
This is done to address virtualization scenarios where the host has the
microcode update applied, but the hypervisor is not yet updated to expose the
CPUID to the guest. If the host has updated microcode the protection takes
effect; otherwise a few CPU cycles are wasted pointlessly.
The state in the tsx_async_abort sysfs file reflects this situation
accordingly.
Mitigation mechanism
--------------------
The kernel detects the affected CPUs and the presence of the microcode which is
required. If a CPU is affected and the microcode is available, then the kernel
enables the mitigation by default.
The mitigation can be controlled at boot time via a kernel command line option.
See :ref:`taa_mitigation_control_command_line`.
.. _virt_mechanism:
Virtualization mitigation
^^^^^^^^^^^^^^^^^^^^^^^^^
Affected systems where the host has TAA microcode and TAA is mitigated by
having disabled TSX previously, are not vulnerable regardless of the status
of the VMs.
In all other cases, if the host either does not have the TAA microcode or
the kernel is not mitigated, the system might be vulnerable.
.. _taa_mitigation_control_command_line:
Mitigation control on the kernel command line
---------------------------------------------
The kernel command line allows to control the TAA mitigations at boot time with
the option "tsx_async_abort=". The valid arguments for this option are:
============ =============================================================
off This option disables the TAA mitigation on affected platforms.
If the system has TSX enabled (see next parameter) and the CPU
is affected, the system is vulnerable.
full TAA mitigation is enabled. If TSX is enabled, on an affected
system it will clear CPU buffers on ring transitions. On
systems which are MDS-affected and deploy MDS mitigation,
TAA is also mitigated. Specifying this option on those
systems will have no effect.
full,nosmt The same as tsx_async_abort=full, with SMT disabled on
vulnerable CPUs that have TSX enabled. This is the complete
mitigation. When TSX is disabled, SMT is not disabled because
CPU is not vulnerable to cross-thread TAA attacks.
============ =============================================================
Merge 4.9.204 into android-4.9-q Changes in 4.9.204 net/mlx4_en: fix mlx4 ethtool -N insertion net: rtnetlink: prevent underflows in do_setvfinfo() sfc: Only cancel the PPS workqueue if it exists net/mlx5e: Fix set vf link state error flow net/sched: act_pedit: fix WARN() in the traffic path gpio: max77620: Fixup debounce delays tools: gpio: Correctly add make dependencies for gpio_utils Revert "fs: ocfs2: fix possible null-pointer dereferences in ocfs2_xa_prepare_entry()" mm/ksm.c: don't WARN if page is still mapped in remove_stable_node() platform/x86: asus-nb-wmi: Support ALS on the Zenbook UX430UQ platform/x86: asus-wmi: Only Tell EC the OS will handle display hotkeys from asus_nb_wmi mwifiex: Fix NL80211_TX_POWER_LIMITED ALSA: isight: fix leak of reference to firewire unit in error path of .probe callback printk: fix integer overflow in setup_log_buf() gfs2: Fix marking bitmaps non-full synclink_gt(): fix compat_ioctl() powerpc: Fix signedness bug in update_flash_db() powerpc/eeh: Fix use of EEH_PE_KEEP on wrong field brcmsmac: AP mode: update beacon when TIM changes ath10k: allocate small size dma memory in ath10k_pci_diag_write_mem spi: sh-msiof: fix deferred probing mmc: mediatek: fix cannot receive new request when msdc_cmd_is_ready fail btrfs: handle error of get_old_root gsmi: Fix bug in append_to_eventlog sysfs handler misc: mic: fix a DMA pool free failure m68k: fix command-line parsing when passed from u-boot amiflop: clean up on errors during setup scsi: ips: fix missing break in switch KVM/x86: Fix invvpid and invept register operand size in 64-bit mode scsi: isci: Use proper enumerated type in atapi_d2h_reg_frame_handler scsi: isci: Change sci_controller_start_task's return type to sci_status scsi: iscsi_tcp: Explicitly cast param in iscsi_sw_tcp_host_get_param clk: mmp2: fix the clock id for sdh2_clk and sdh3_clk ASoC: tegra_sgtl5000: fix device_node refcounting scsi: dc395x: fix dma API usage in srb_done scsi: dc395x: fix DMA API usage in sg_update_list net: fix warning in af_unix net: ena: Fix Kconfig dependency on X86 xfs: fix use-after-free race in xfs_buf_rele kprobes, x86/ptrace.h: Make regs_get_kernel_stack_nth() not fault on bad stack ALSA: i2c/cs8427: Fix int to char conversion macintosh/windfarm_smu_sat: Fix debug output USB: misc: appledisplay: fix backlight update_status return code usbip: tools: fix atoi() on non-null terminated string SUNRPC: Fix a compile warning for cmpxchg64() sunrpc: safely reallow resvport min/max inversion atm: zatm: Fix empty body Clang warnings s390/perf: Return error when debug_register fails spi: omap2-mcspi: Set FIFO DMA trigger level to word length sparc: Fix parport build warnings. ceph: fix dentry leak in ceph_readdir_prepopulate rtc: s35390a: Change buf's type to u8 in s35390a_init f2fs: fix to spread clear_cold_data() mISDN: Fix type of switch control variable in ctrl_teimanager qlcnic: fix a return in qlcnic_dcb_get_capability() net: ethernet: ti: cpsw: unsync mcast entries while switch promisc mode mfd: arizona: Correct calling of runtime_put_sync mfd: mc13xxx-core: Fix PMIC shutdown when reading ADC values mfd: max8997: Enale irq-wakeup unconditionally selftests/ftrace: Fix to test kprobe $comm arg only if available thermal: rcar_thermal: Prevent hardware access during system suspend powerpc/process: Fix flush_all_to_thread for SPE sparc64: Rework xchg() definition to avoid warnings. fs/ocfs2/dlm/dlmdebug.c: fix a sleep-in-atomic-context bug in dlm_print_one_mle() mm/page-writeback.c: fix range_cyclic writeback vs writepages deadlock macsec: update operstate when lower device changes macsec: let the administrator set UP state even if lowerdev is down um: Make line/tty semantics use true write IRQ linux/bitmap.h: handle constant zero-size bitmaps correctly linux/bitmap.h: fix type of nbits in bitmap_shift_right() hfsplus: fix BUG on bnode parent update hfs: fix BUG on bnode parent update hfsplus: prevent btree data loss on ENOSPC hfs: prevent btree data loss on ENOSPC hfsplus: fix return value of hfsplus_get_block() hfs: fix return value of hfs_get_block() hfsplus: update timestamps on truncate() hfs: update timestamp on truncate() fs/hfs/extent.c: fix array out of bounds read of array extent mm/memory_hotplug: make add_memory() take the device_hotplug_lock igb: shorten maximum PHC timecounter update interval ntb_netdev: fix sleep time mismatch ntb: intel: fix return value for ndev_vec_mask() arm64: makefile fix build of .i file in external module case ocfs2: don't put and assigning null to bh allocated outside ocfs2: fix clusters leak in ocfs2_defrag_extent() net: do not abort bulk send on BQL status sched/fair: Don't increase sd->balance_interval on newidle balance audit: print empty EXECVE args wlcore: Fix the return value in case of error in 'wlcore_vendor_cmd_smart_config_start()' rtl8xxxu: Fix missing break in switch brcmsmac: never log "tid x is not agg'able" by default wireless: airo: potential buffer overflow in sprintf() rtlwifi: rtl8192de: Fix misleading REG_MCUFWDL information scsi: mpt3sas: Fix Sync cache command failure during driver unload scsi: mpt3sas: Fix driver modifying persistent data in Manufacturing page11 scsi: megaraid_sas: Fix msleep granularity scsi: lpfc: fcoe: Fix link down issue after 1000+ link bounces dlm: fix invalid free dlm: don't leak kernel pointer to userspace ACPICA: Use %d for signed int print formatting instead of %u net: bcmgenet: return correct value 'ret' from bcmgenet_power_down sock: Reset dst when changing sk_mark via setsockopt pinctrl: qcom: spmi-gpio: fix gpio-hog related boot issues pinctrl: lpc18xx: Use define directive for PIN_CONFIG_GPIO_PIN_INT pinctrl: zynq: Use define directive for PIN_CONFIG_IO_STANDARD PCI: keystone: Use quirk to limit MRRS for K2G spi: omap2-mcspi: Fix DMA and FIFO event trigger size mismatch mm/memory_hotplug: Do not unlock when fails to take the device_hotplug_lock Bluetooth: Fix invalid-free in bcsp_close() KVM: MMU: Do not treat ZONE_DEVICE pages as being reserved ath9k_hw: fix uninitialized variable data dm: use blk_set_queue_dying() in __dm_destroy() arm64: fix for bad_mode() handler to always result in panic cpufreq: Skip cpufreq resume if it's not suspended ocfs2: remove ocfs2_is_o2cb_active() ARM: 8904/1: skip nomap memblocks while finding the lowmem/highmem boundary ARC: perf: Accommodate big-endian CPU x86/insn: Fix awk regexp warnings x86/speculation: Fix incorrect MDS/TAA mitigation status x86/speculation: Fix redundant MDS mitigation message nfc: port100: handle command failure cleanly l2tp: don't use l2tp_tunnel_find() in l2tp_ip and l2tp_ip6 media: vivid: Set vid_cap_streaming and vid_out_streaming to true media: vivid: Fix wrong locking that causes race conditions on streaming stop media: usbvision: Fix races among open, close, and disconnect cpufreq: Add NULL checks to show() and store() methods of cpufreq media: uvcvideo: Fix error path in control parsing failure media: b2c2-flexcop-usb: add sanity checking media: cxusb: detect cxusb_ctrl_msg error in query media: imon: invalid dereference in imon_touch_event virtio_console: reset on out of memory virtio_console: don't tie bufs to a vq virtio_console: allocate inbufs in add_port() only if it is needed virtio_ring: fix return code on DMA mapping fails virtio_console: fix uninitialized variable use virtio_console: drop custom control queue cleanup virtio_console: move removal code usbip: tools: fix fd leakage in the function of read_attr_usbip_status usb-serial: cp201x: support Mark-10 digital force gauge USB: chaoskey: fix error case of a timeout appledisplay: fix error handling in the scheduled work USB: serial: mos7840: add USB ID to support Moxa UPort 2210 USB: serial: mos7720: fix remote wakeup USB: serial: mos7840: fix remote wakeup USB: serial: option: add support for DW5821e with eSIM support USB: serial: option: add support for Foxconn T77W968 LTE modules staging: comedi: usbduxfast: usbduxfast_ai_cmdtest rounding error powerpc/64s: support nospectre_v2 cmdline option powerpc/book3s64: Fix link stack flush on context switch KVM: PPC: Book3S HV: Flush link stack on guest exit to host kernel Linux 4.9.204 Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
2019-11-28 18:47:59 +01:00
Not specifying this option is equivalent to "tsx_async_abort=full". For
processors that are affected by both TAA and MDS, specifying just
"tsx_async_abort=off" without an accompanying "mds=off" will have no
effect as the same mitigation is used for both vulnerabilities.
Merge 4.9.202 into android-4.9-q Changes in 4.9.202 kvm: mmu: Don't read PDPTEs when paging is not enabled Bluetooth: hci_ldisc: Postpone HCI_UART_PROTO_READY bit set in hci_uart_set_proto() MIPS: BCM63XX: fix switch core reset on BCM6368 usb: gadget: core: unmap request from DMA only if previously mapped KVM: x86: use Intel speculation bugs and features as derived in generic x86 code x86/msr: Add the IA32_TSX_CTRL MSR x86/cpu: Add a helper function x86_read_arch_cap_msr() x86/cpu: Add a "tsx=" cmdline option with TSX disabled by default x86/speculation/taa: Add mitigation for TSX Async Abort x86/speculation/taa: Add sysfs reporting for TSX Async Abort kvm/x86: Export MDS_NO=0 to guests when TSX is enabled x86/tsx: Add "auto" option to the tsx= cmdline parameter x86/speculation/taa: Add documentation for TSX Async Abort x86/tsx: Add config options to set tsx=on|off|auto x86/speculation/taa: Fix printing of TAA_MSG_SMT on IBRS_ALL CPUs KVM: x86: simplify ept_misconfig KVM: x86: extend usage of RET_MMIO_PF_* constants kvm: Convert kvm_lock to a mutex kvm: x86: Do not release the page inside mmu_set_spte() KVM: x86: make FNAME(fetch) and __direct_map more similar KVM: x86: remove now unneeded hugepage gfn adjustment KVM: x86: change kvm_mmu_page_get_gfn BUG_ON to WARN_ON KVM: x86: Add is_executable_pte() KVM: x86: add tracepoints around __direct_map and FNAME(fetch) KVM: vmx, svm: always run with EFER.NXE=1 when shadow paging is active x86/bugs: Add ITLB_MULTIHIT bug infrastructure cpu/speculation: Uninline and export CPU mitigations helpers kvm: mmu: ITLB_MULTIHIT mitigation kvm: Add helper function for creating VM worker threads kvm: x86: mmu: Recovery of shattered NX large pages Documentation: Add ITLB_MULTIHIT documentation Linux 4.9.202 Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
2019-11-16 11:05:12 +01:00
The kernel command line also allows to control the TSX feature using the
parameter "tsx=" on CPUs which support TSX control. MSR_IA32_TSX_CTRL is used
to control the TSX feature and the enumeration of the TSX feature bits (RTM
and HLE) in CPUID.
The valid options are:
============ =============================================================
off Disables TSX on the system.
Note that this option takes effect only on newer CPUs which are
not vulnerable to MDS, i.e., have MSR_IA32_ARCH_CAPABILITIES.MDS_NO=1
and which get the new IA32_TSX_CTRL MSR through a microcode
update. This new MSR allows for the reliable deactivation of
the TSX functionality.
on Enables TSX.
Although there are mitigations for all known security
vulnerabilities, TSX has been known to be an accelerator for
several previous speculation-related CVEs, and so there may be
unknown security risks associated with leaving it enabled.
auto Disables TSX if X86_BUG_TAA is present, otherwise enables TSX
on the system.
============ =============================================================
Not specifying this option is equivalent to "tsx=off".
The following combinations of the "tsx_async_abort" and "tsx" are possible. For
affected platforms tsx=auto is equivalent to tsx=off and the result will be:
========= ========================== =========================================
tsx=on tsx_async_abort=full The system will use VERW to clear CPU
buffers. Cross-thread attacks are still
possible on SMT machines.
tsx=on tsx_async_abort=full,nosmt As above, cross-thread attacks on SMT
mitigated.
tsx=on tsx_async_abort=off The system is vulnerable.
tsx=off tsx_async_abort=full TSX might be disabled if microcode
provides a TSX control MSR. If so,
system is not vulnerable.
tsx=off tsx_async_abort=full,nosmt Ditto
tsx=off tsx_async_abort=off ditto
========= ========================== =========================================
For unaffected platforms "tsx=on" and "tsx_async_abort=full" does not clear CPU
buffers. For platforms without TSX control (MSR_IA32_ARCH_CAPABILITIES.MDS_NO=0)
"tsx" command line argument has no effect.
For the affected platforms below table indicates the mitigation status for the
combinations of CPUID bit MD_CLEAR and IA32_ARCH_CAPABILITIES MSR bits MDS_NO
and TSX_CTRL_MSR.
======= ========= ============= ========================================
MDS_NO MD_CLEAR TSX_CTRL_MSR Status
======= ========= ============= ========================================
0 0 0 Vulnerable (needs microcode)
0 1 0 MDS and TAA mitigated via VERW
1 1 0 MDS fixed, TAA vulnerable if TSX enabled
because MD_CLEAR has no meaning and
VERW is not guaranteed to clear buffers
1 X 1 MDS fixed, TAA can be mitigated by
VERW or TSX_CTRL_MSR
======= ========= ============= ========================================
Mitigation selection guide
--------------------------
1. Trusted userspace and guests
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
If all user space applications are from a trusted source and do not execute
untrusted code which is supplied externally, then the mitigation can be
disabled. The same applies to virtualized environments with trusted guests.
2. Untrusted userspace and guests
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
If there are untrusted applications or guests on the system, enabling TSX
might allow a malicious actor to leak data from the host or from other
processes running on the same physical core.
If the microcode is available and the TSX is disabled on the host, attacks
are prevented in a virtualized environment as well, even if the VMs do not
explicitly enable the mitigation.
.. _taa_default_mitigations:
Default mitigations
-------------------
The kernel's default action for vulnerable processors is:
- Deploy TSX disable mitigation (tsx_async_abort=full tsx=off).