Xenial update to 4.4.126 stable release

[Juerg Haefliger]

SRU Justification

Impact:
   The upstream process for stable tree updates is quite similar
   in scope to the Ubuntu SRU process, e.g., each patch has to
   demonstrably fix a bug, and each patch is vetted by upstream
   by originating either directly from a mainline/stable Linux tree
   or a minimally backported form of that patch. The 4.4.126 upstream
   stable stable patch set is now available. It should be included
   in the Ubuntu kernel as well.

   git://git.kernel.org/

TEST CASE: TBD

   The following patches from the 4.4.126 stable release shall be
   applied:

   * Linux 4.4.126
   * net: systemport: Rewrite __bcm_sysport_tx_reclaim()
   * net: fec: Fix unbalanced PM runtime calls
   * ieee802154: 6lowpan: fix possible NULL deref in lowpan_device_event()
   * s390/qeth: on channel error, reject further cmd requests
   * s390/qeth: lock read device while queueing next buffer
   * s390/qeth: when thread completes, wake up all waiters
   * s390/qeth: free netdevice when removing a card
   * team: Fix double free in error path
   * skbuff: Fix not waking applications when errors are enqueued
   * net: Only honor ifindex in IP_PKTINFO if non-0
   * netlink: avoid a double skb free in genlmsg_mcast()
   * net/iucv: Free memory obtained by kzalloc
   * net: ethernet: ti: cpsw: add check for in-band mode setting with RGMII PHY interface
   * net: ethernet: arc: Fix a potential memory leak if an optional regulator is deferred
   * l2tp: do not accept arbitrary sockets
   * ipv6: fix access to non-linear packet in ndisc_fill_redirect_hdr_option()
   * dccp: check sk for closed state in dccp_sendmsg()
   * net: Fix hlist corruptions in inet_evict_bucket()
   * Revert "genirq: Use irqd_get_trigger_type to compare the trigger type for shared IRQs"
   * scsi: sg: don't return bogus Sg_requests

[Launchpad Janitor (janitor)]

This bug was fixed in the package linux - 4.4.0-127.153

---------------
linux (4.4.0-127.153) xenial; urgency=medium

  * CVE-2018-3639 (powerpc)
    - powerpc/pseries: Support firmware disable of RFI flush
    - powerpc/powernv: Support firmware disable of RFI flush
    - powerpc/rfi-flush: Move the logic to avoid a redo into the debugfs code
    - powerpc/rfi-flush: Make it possible to call setup_rfi_flush() again
    - powerpc/rfi-flush: Always enable fallback flush on pseries
    - powerpc/rfi-flush: Differentiate enabled and patched flush types
    - powerpc/rfi-flush: Call setup_rfi_flush() after LPM migration
    - powerpc/pseries: Add new H_GET_CPU_CHARACTERISTICS flags
    - powerpc: Add security feature flags for Spectre/Meltdown
    - powerpc/pseries: Set or clear security feature flags
    - powerpc/powernv: Set or clear security feature flags
    - powerpc/64s: Move cpu_show_meltdown()
    - powerpc/64s: Enhance the information in cpu_show_meltdown()
    - powerpc/powernv: Use the security flags in pnv_setup_rfi_flush()
    - powerpc/pseries: Use the security flags in pseries_setup_rfi_flush()
    - powerpc/64s: Wire up cpu_show_spectre_v1()
    - powerpc/64s: Wire up cpu_show_spectre_v2()
    - powerpc/pseries: Fix clearing of security feature flags
    - powerpc: Move default security feature flags
    - powerpc/pseries: Restore default security feature flags on setup
    - SAUCE: powerpc/64s: Add support for a store forwarding barrier at kernel
      entry/exit

  * CVE-2018-3639 (x86)
    - SAUCE: Clean up IBPB and IBRS control functions and macros
    - SAUCE: Fix up IBPB and IBRS kernel parameters documentation
    - SAUCE: Remove #define X86_FEATURE_PTI
    - x86/cpufeature: Move some of the scattered feature bits to x86_capability
    - x86/cpufeature: Cleanup get_cpu_cap()
    - x86/cpu: Probe CPUID leaf 6 even when cpuid_level == 6
    - x86/cpufeatures: Add CPUID_7_EDX CPUID leaf
    - x86/cpufeatures: Add Intel feature bits for Speculation Control
    - SAUCE: x86/kvm: Expose SPEC_CTRL from the leaf
    - x86/cpufeatures: Add AMD feature bits for Speculation Control
    - x86/msr: Add definitions for new speculation control MSRs
    - SAUCE: x86/msr: Rename MSR spec control feature bits
    - x86/pti: Do not enable PTI on CPUs which are not vulnerable to Meltdown
    - x86/cpufeature: Blacklist SPEC_CTRL/PRED_CMD on early Spectre v2 microcodes
    - x86/speculation: Add basic IBPB (Indirect Branch Prediction Barrier) support
    - x86/speculation: Add <asm/msr-index.h> dependency
    - x86/cpufeatures: Clean up Spectre v2 related CPUID flags
    - x86/cpuid: Fix up "virtual" IBRS/IBPB/STIBP feature bits on Intel
    - SAUCE: x86/speculation: Move vendor specific IBRS/IBPB control code
    - SAUCE: x86: Add alternative_msr_write
    - SAUCE: x86/nospec: Simplify alternative_msr_write()
    - SAUCE: x86/bugs: Concentrate bug detection into a separate function
    - SAUCE: x86/bugs: Concentrate bug reporting into a separate function
    - arch: Introduce post-init read-only memory
    - SAUCE: x86/bugs: Read SPEC_CTRL MSR during boot and re-use reserved bits
    - SAUCE: x86/bugs, KVM: Support the combination of guest a...