1. 08 2月, 2018 5 次提交
  2. 24 1月, 2018 9 次提交
  3. 22 1月, 2018 4 次提交
    • L
      Linux 4.15-rc9 · 0c5b9b5d
      Linus Torvalds 提交于
      0c5b9b5d
    • L
      Merge branch 'x86-pti-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip · 55151142
      Linus Torvalds 提交于
      Pull x86 pti fixes from Thomas Gleixner:
       "A small set of fixes for the meltdown/spectre mitigations:
      
         - Make kprobes aware of retpolines to prevent probes in the retpoline
           thunks.
      
         - Make the machine check exception speculation protected. MCE used to
           issue an indirect call directly from the ASM entry code. Convert
           that to a direct call into a C-function and issue the indirect call
           from there so the compiler can add the retpoline protection,
      
         - Make the vmexit_fill_RSB() assembly less stupid
      
         - Fix a typo in the PTI documentation"
      
      * 'x86-pti-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
        x86/retpoline: Optimize inline assembler for vmexit_fill_RSB
        x86/pti: Document fix wrong index
        kprobes/x86: Disable optimizing on the function jumps to indirect thunk
        kprobes/x86: Blacklist indirect thunk functions for kprobes
        retpoline: Introduce start/end markers of indirect thunk
        x86/mce: Make machine check speculation protected
      55151142
    • L
      Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip · 319f1e04
      Linus Torvalds 提交于
      Pull x86 kexec fix from Thomas Gleixner:
       "A single fix for the WBINVD issue introduced by the SME support which
        causes kexec fails on non AMD/SME capable CPUs. Issue WBINVD only when
        the CPU has SME and avoid doing so in a loop"
      
      [ Side note: this patch fixes the problem, but it isn't entirely clear
        why it is required. The wbinvd should just work regardless, but there
        seems to be some system - as opposed to CPU - issue, since the wbinvd
        causes more problems later in the shutdown sequence, but wbinvd
        instructions while the system is still active are not problematic.
      
        Possibly some SMI or pending machine check issue on the affected system ]
      
      * 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
        x86/mm: Rework wbinvd, hlt operation in stop_this_cpu()
      319f1e04
    • L
      Merge branch 'irq-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip · 66f81624
      Linus Torvalds 提交于
      Pull irq fix from Thomas Gleixner:
       "A single fix for the new matrix allocator to prevent vector exhaustion
        by certain network drivers which allocate gazillions of unused vectors
        which cannot be put into reservation mode due to MSI and the lack of
        MSI entry masking.
      
        The fix/workaround is to spread the vectors across CPUs by searching
        the supplied target CPU mask for the CPU with the smallest number of
        allocated vectors"
      
      * 'irq-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
        irq/matrix: Spread interrupts on allocation
      66f81624
  4. 21 1月, 2018 7 次提交
    • L
      Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mattst88/alpha · d517bb79
      Linus Torvalds 提交于
      Pull alpha fixes from Matt Turner:
       "A build fix and a regression fix"
      
      * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mattst88/alpha:
        alpha/PCI: Fix noname IRQ level detection
        alpha: extend memset16 to EV6 optimised routines
      d517bb79
    • L
      x86: Use __nostackprotect for sme_encrypt_kernel · 91cfc88c
      Laura Abbott 提交于
      Commit bacf6b49 ("x86/mm: Use a struct to reduce parameters for SME
      PGD mapping") moved some parameters into a structure.
      
      The structure was large enough to trigger the stack protection canary in
      sme_encrypt_kernel which doesn't work this early, causing reboots.
      
      Mark sme_encrypt_kernel appropriately to not use the canary.
      
      Fixes: bacf6b49 ("x86/mm: Use a struct to reduce parameters for SME PGD mapping")
      Signed-off-by: NLaura Abbott <labbott@redhat.com>
      Cc: Tom Lendacky <thomas.lendacky@amd.com>
      Cc: Ingo Molnar <mingo@kernel.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      91cfc88c
    • L
      alpha/PCI: Fix noname IRQ level detection · 86be8993
      Lorenzo Pieralisi 提交于
      The conversion of the alpha architecture PCI host bridge legacy IRQ
      mapping/swizzling to the new PCI host bridge map/swizzle hooks carried
      out through:
      
      commit 0e4c2eeb ("alpha/PCI: Replace pci_fixup_irqs() call with
      host bridge IRQ mapping hooks")
      
      implies that IRQ for devices are now allocated through pci_assign_irq()
      function in pci_device_probe() that is called when a driver matching a
      device is found in order to probe the device through the device driver.
      
      Alpha noname platforms required IRQ level programming to be executed
      in sio_fixup_irq_levels(), that is called in noname_init_pci(), a
      platform hook called within a subsys_initcall.
      
      In noname_init_pci(), present IRQs are detected through
      sio_collect_irq_levels() that check the struct pci_dev->irq number
      to detect if an IRQ has been allocated for the device.
      
      By the time sio_collect_irq_levels() is called, some devices may still
      have not a matching driver loaded to match them (eg loadable module)
      therefore their IRQ allocation is still pending - which means that
      sio_collect_irq_levels() does not programme the correct IRQ level for
      those devices, causing their IRQ handling to be broken when the device
      driver is actually loaded and the device is probed.
      
      Fix the issue by adding code in the noname map_irq() function
      (noname_map_irq()) that, whilst mapping/swizzling the IRQ line, it also
      ensures that the correct IRQ level programming is executed at platform
      level, fixing the issue.
      
      Fixes: 0e4c2eeb ("alpha/PCI: Replace pci_fixup_irqs() call with
      host bridge IRQ mapping hooks")
      Reported-by: NMikulas Patocka <mpatocka@redhat.com>
      Signed-off-by: NLorenzo Pieralisi <lorenzo.pieralisi@arm.com>
      Cc: stable@vger.kernel.org # 4.14
      Cc: Bjorn Helgaas <bhelgaas@google.com>
      Cc: Richard Henderson <rth@twiddle.net>
      Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
      Cc: Mikulas Patocka <mpatocka@redhat.com>
      Cc: Meelis Roos <mroos@linux.ee>
      Signed-off-by: NMatt Turner <mattst88@gmail.com>
      86be8993
    • L
      Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm · 24b61240
      Linus Torvalds 提交于
      Pull KVM fixes from Radim Krčmář:
       "ARM:
         - fix incorrect huge page mappings on systems using the contiguous
           hint for hugetlbfs
         - support alternative GICv4 init sequence
         - correctly implement the ARM SMCC for HVC and SMC handling
      
        PPC:
         - add KVM IOCTL for reporting vulnerability and workaround status
      
        s390:
         - provide userspace interface for branch prediction changes in
           firmware
      
        x86:
         - use correct macros for bits"
      
      * tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm:
        KVM: s390: wire up bpb feature
        KVM: PPC: Book3S: Provide information about hardware/firmware CVE workarounds
        KVM/x86: Fix wrong macro references of X86_CR0_PG_BIT and X86_CR4_PAE_BIT in kvm_valid_sregs()
        arm64: KVM: Fix SMCCC handling of unimplemented SMC/HVC calls
        KVM: arm64: Fix GICv4 init when called from vgic_its_create
        KVM: arm/arm64: Check pagesize when allocating a hugepage at Stage 2
      24b61240
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      Merge tag 'mips_fixes_4.15_2' of git://git.kernel.org/pub/scm/linux/kernel/git/jhogan/mips · e6252e7f
      Linus Torvalds 提交于
      Pull MIPS fixes from James Hogan:
       "Some final MIPS fixes for 4.15, including important build fixes and a
        MAINTAINERS update:
      
         - Add myself as MIPS co-maintainer.
      
         - Fix various all*config build failures (particularly as a result of
           switching the default MIPS platform to the "generic" platform).
      
         - Fix GCC7 build failures (duplicate const and questionable calls to
           missing __multi3 intrinsic on mips64r6).
      
         - Fix warnings when CPU Idle is enabled (4.14).
      
         - Fix AR7 serial output (since 3.17).
      
         - Fix ralink platform_get_irq error checking (since 3.12)"
      
      * tag 'mips_fixes_4.15_2' of git://git.kernel.org/pub/scm/linux/kernel/git/jhogan/mips:
        MAINTAINERS: Add James as MIPS co-maintainer
        MIPS: Fix undefined reference to physical_memsize
        MIPS: Implement __multi3 for GCC7 MIPS64r6 builds
        MIPS: mm: Fix duplicate "const" on insn_table_MM
        MIPS: CM: Drop WARN_ON(vp != 0)
        MIPS: ralink: Fix platform_get_irq's error checking
        MIPS: Fix CPS SMP NS16550 UART defaults
        MIPS: BCM47XX Avoid compile error with MIPS allnoconfig
        MIPS: RB532: Avoid undefined mac_pton without GENERIC_NET_UTILS
        MIPS: RB532: Avoid undefined early_serial_setup() without SERIAL_8250_CONSOLE
        MIPS: ath25: Avoid undefined early_serial_setup() without SERIAL_8250_CONSOLE
        MIPS: AR7: ensure the port type's FCR value is used
      e6252e7f
    • C
      KVM: s390: wire up bpb feature · 35b3fde6
      Christian Borntraeger 提交于
      The new firmware interfaces for branch prediction behaviour changes
      are transparently available for the guest. Nevertheless, there is
      new state attached that should be migrated and properly resetted.
      Provide a mechanism for handling reset, migration and VSIE.
      Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>
      Reviewed-by: NDavid Hildenbrand <david@redhat.com>
      Reviewed-by: NCornelia Huck <cohuck@redhat.com>
      [Changed capability number to 152. - Radim]
      Signed-off-by: NRadim Krčmář <rkrcmar@redhat.com>
      35b3fde6
    • R
      Merge tag 'kvm-ppc-cve-4.15-2' of git://git.kernel.org/pub/scm/linux/kernel/git/paulus/powerpc · 29d24e3f
      Radim Krčmář 提交于
      Add PPC KVM ioctl to report vulnerability and workaround status to userspace.
      29d24e3f
  5. 20 1月, 2018 15 次提交
    • L
      Merge tag 'scsi-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi · 8dd903d2
      Linus Torvalds 提交于
      Pull SCSI fix from James Bottomley:
       "One fix for SAS attached SATA CD-ROMs. It turns out that the libata
        handling of CD devices relies on the SCSI error handler, so disable
        async aborts (which don't start the error handler) for these devices"
      
      * tag 'scsi-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi:
        scsi: libsas: Disable asynchronous aborts for SATA devices
      8dd903d2
    • L
      Merge tag 'for-4.15/dm-fixes-2' of... · 1cf55613
      Linus Torvalds 提交于
      Merge tag 'for-4.15/dm-fixes-2' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm
      
      Pull device mapper fixes from Mike Snitzer:
       "All fixes marked for stable:
      
         - Fix DM thinp btree corruption seen when inserting a new key/value
           pair into a full root node.
      
         - Fix DM thinp btree removal deadlock due to artificially low number
           of allowed concurrent locks allowed.
      
         - Fix possible DM crypt corruption if kernel keyring service is used.
           Only affects ciphers using following IVs: essiv, lmk and tcw.
      
         - Two DM crypt device initialization error checking fixes.
      
         - Fix DM integrity to allow use of async ciphers that require DMA"
      
      * tag 'for-4.15/dm-fixes-2' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm:
        dm crypt: fix error return code in crypt_ctr()
        dm crypt: wipe kernel key copy after IV initialization
        dm integrity: don't store cipher request on the stack
        dm crypt: fix crash by adding missing check for auth key size
        dm btree: fix serious bug in btree_split_beneath()
        dm thin metadata: THIN_MAX_CONCURRENT_LOCKS should be 6
      1cf55613
    • L
      Merge tag 'trace-v4.15-rc4-3' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace · ec835f81
      Linus Torvalds 提交于
      Pull tracing fixes from Steven Rostedt:
       "Two more small fixes
      
         - The conversion of enums into their actual numbers to display in the
           event format file had an off-by-one bug, that could cause an enum
           not to be converted, and break user space parsing tools.
      
         - A fix to a previous fix to bring back the context recursion checks.
           The interrupt case checks for NMI, IRQ and softirq, but the softirq
           returned the same number regardless if it was set or not, although
           the logic would force it to be set if it were hit"
      
      * tag 'trace-v4.15-rc4-3' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
        tracing: Fix converting enum's from the map in trace_event_eval_update()
        ring-buffer: Fix duplicate results in mapping context to bits in recursive lock
      ec835f81
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      Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input · 672bb0fa
      Linus Torvalds 提交于
      Pull input fixes from Dmitry Torokhov:
      
       - a fix for use-after-free in Synaptics RMI4 driver
      
       - correction to multitouch contact tracking on certain ALPS touchpads
         (which got broken when we tried to fix the 2-finger scrolling)
      
       - touchpad on Lenovo T640p is switched over to SMbus/RMI
      
       - a few device node refcount fixes
      
      * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input:
        Input: synaptics-rmi4 - prevent UAF reported by KASAN
        Input: ALPS - fix multi-touch decoding on SS4 plus touchpads
        Input: synaptics - Lenovo Thinkpad T460p devices should use RMI
        Input: of_touchscreen - add MODULE_LICENSE
        Input: 88pm860x-ts - fix child-node lookup
        Input: twl6040-vibra - fix child-node lookup
        Input: twl4030-vibra - fix sibling-node lookup
      672bb0fa
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      Merge branch 'i2c/for-current-fixed' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux · 9bdbaeba
      Linus Torvalds 提交于
      Pull i2c fixes from Wolfram Sang:
       "Two bugfixes for the I2C core: Lixing Wang fixed a refcounting problem
        with DT nodes. Jeremy Compostella fixed a buffer overflow possibility
        when using a 'don't use' ioctl interface directly"
      
      * 'i2c/for-current-fixed' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux:
        i2c: core-smbus: prevent stack corruption on read I2C_BLOCK_DATA
        i2c: core: decrease reference count of device node in i2c_unregister_device
      9bdbaeba
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      Merge branch 'for-4.15-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/libata · 9f77a11a
      Linus Torvalds 提交于
      Pull libata fixlet from Tejun Heo:
       "This just adds one more entry for liteon optical drives to the device
        blacklist for large IOs.
      
        The change is very low risk"
      
      * 'for-4.15-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/libata:
        libata: apply MAX_SEC_1024 to all LITEON EP1 series devices
      9f77a11a
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      Merge branch 'for-4.15-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup · 8b335c7d
      Linus Torvalds 提交于
      Pull cgroup fix from Tejun Heo:
       "cgroup.threads should be delegatable (ie. a container should be able
        to write to it from inside) but was missing the flag.
      
        The change is very low risk"
      
      * 'for-4.15-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
        cgroup: make cgroup.threads delegatable
      8b335c7d
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      Merge branch 'for-4.15-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq · a2c9c1c0
      Linus Torvalds 提交于
      Pull workqueue fixlet from Tejun Heo:
       "One patch to add touch_nmi_watchdog() while dumping workqueue debug
        messages to avoid triggering the lockup detector spuriously.
      
        The change is very low risk"
      
      * 'for-4.15-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq:
        workqueue: avoid hard lockups in show_workqueue_state()
      a2c9c1c0
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      Merge tag 'armsoc-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm/arm-soc · 6ec8765f
      Linus Torvalds 提交于
      Pull ARM SoC fixes from Arnd Bergmann:
       "We have various small DT fixes, and one important regression fix:
      
        The recent device tree bugfixes that were intended to address issues
        that 'dtc' started warning about in 4.15 fixed various USB PHY device
        nodes, but it turns out that we had code that depended on those nodes
        being incorrect and the probe failing with a particular error code.
        With the workaround we can also deal with correct device nodes.
      
        The DT fixes include:
      
         - Allwinner A10 and A20 had the display pipeline set up incorrectly
           (introduced in v4.15)
      
         - The Altera PMU lacked an interrupt-parent (never worked)
      
         - Pin muxing on the Openblocks A7 (never worked)
      
         - Clocks might get set up wrong on Armada 7K/8K (4.15 regression)
      
        We now have additional device tree patches to address all the
        remaining warnings introduced in 4.15, but decided to queue them for
        4.16 instead, to avoid risking another regression like the USB PHY
        thing mentioned above.
      
      * tag 'armsoc-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm/arm-soc:
        phy: work around 'phys' references to usb-nop-xceiv devices
        ARM: sunxi_defconfig: Enable CMA
        arm64: dts: socfpga: add missing interrupt-parent
        ARM: dts: sun[47]i: Fix display backend 1 output to TCON0 remote endpoint
        ARM64: dts: marvell: armada-cp110: Fix clock resources for various node
        ARM: dts: da850-lcdk: Remove leading 0x and 0s from unit address
        ARM: dts: kirkwood: fix pin-muxing of MPP7 on OpenBlocks A7
      6ec8765f
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      Merge tag 'powerpc-4.15-8' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux · 4917d5df
      Linus Torvalds 提交于
      Pull powerpc fixes from Michael Ellerman:
       "More than we'd like after rc8, but nothing very alarming either, just
        tying up loose ends before the release:
      
        Since we changed powernv to use cpufreq_get() from show_cpuinfo(), we
        see warnings with PREEMPT enabled. But the preempt_disable() in
        show_cpuinfo() doesn't actually prevent CPU hotplug as it suggests, so
        remove it.
      
        Two updates to the recently merged RFI flush code. Wire up the generic
        sysfs file to report the status, and add a debugfs file to allow
        enabling/disabling it at runtime.
      
        Two updates to xmon, one to add the RFI flush related fields to the
        paca dump, and another to not use hashed pointers in the paca dump.
      
        And one minor fix to add a missing include of linux/types.h in
        asm/hvcall.h, not seen to break the build in upstream, but correct
        anyway.
      
        Thanks to: Benjamin Herrenschmidt, Michal Suchanek, Nicholas Piggin"
      
      * tag 'powerpc-4.15-8' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux:
        powerpc/pseries: include linux/types.h in asm/hvcall.h
        powerpc/64s: Allow control of RFI flush via debugfs
        powerpc/64s: Wire up cpu_show_meltdown()
        powerpc: Don't preempt_disable() in show_cpuinfo()
        powerpc/xmon: Don't print hashed pointers in paca dump
        powerpc/xmon: Add RFI flush related fields to paca dump
      4917d5df
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      Merge tag 'drm-fixes-for-v4.15-rc9' of git://people.freedesktop.org/~airlied/linux · 9abc9378
      Linus Torvalds 提交于
      Pull drm fixes from Dave Airlie:
       "Nouveau, i915, vmwgfx and sun4i regression fixes.
      
        The i915 change fixes a display corruption problem introduced in 4.15,
        the nouveau changes are for regressions in 4.15, one of the vmwgfx
        fixes goes back a little further, the other is a 4.15 regression fix,
        the 3 sun4i changes fix blank HDMI output on those devices"
      
      * tag 'drm-fixes-for-v4.15-rc9' of git://people.freedesktop.org/~airlied/linux:
        drm/nouveau/mmu/mcp77: fix regressions in stolen memory handling
        drm/nouveau/bar/gk20a: Avoid bar teardown during init
        drm/nouveau/drm/nouveau: Pass the proper arguments to nvif_object_map_handle()
        drm/vmwgfx: fix memory corruption with legacy/sou connectors
        drm/vmwgfx: Fix a boot time warning
        drm/i915: Fix deadlock in i830_disable_pipe()
        drm/i915: Redo plane sanitation during readout
        drm/i915: Add .get_hw_state() method for planes
        drm/sun4i: hdmi: Add missing rate halving check in sun4i_tmds_determine_rate
        drm/sun4i: hdmi: Fix incorrect assignment in sun4i_tmds_determine_rate
        drm/sun4i: hdmi: Check for unset best_parent in sun4i_tmds_determine_rate
      9abc9378
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      Merge branch 'akpm' (patches from Andrew) · d342740e
      Linus Torvalds 提交于
      Merge misc fixes from Andrew Morton:
       "6 fixes"
      
      * emailed patches from Andrew Morton <akpm@linux-foundation.org>:
        sparse doesn't support struct randomization
        proc: fix coredump vs read /proc/*/stat race
        scripts/gdb/linux/tasks.py: fix get_thread_info
        scripts/decodecode: fix decoding for AArch64 (arm64) instructions
        mm/page_owner.c: remove drain_all_pages from init_early_allocated_pages
        mm/memory.c: release locked page in do_swap_page()
      d342740e
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      ia64: Rewrite atomic_add and atomic_sub · 4b664e73
      Matthew Wilcox 提交于
      Force __builtin_constant_p to evaluate whether the argument to atomic_add
      & atomic_sub is constant in the front-end before optimisations which
      can lead GCC to output a call to __bad_increment_for_ia64_fetch_and_add().
      
      See GCC bugzilla 83653.
      Signed-off-by: NJakub Jelinek <jakub@redhat.com>
      Signed-off-by: NMatthew Wilcox <mawilcox@microsoft.com>
      Signed-off-by: NTony Luck <tony.luck@intel.com>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      4b664e73
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      sparse doesn't support struct randomization · a3d6c976
      Matthew Wilcox 提交于
      Without this patch, I drown in a sea of unknown attribute warnings
      
      Link: http://lkml.kernel.org/r/20180117024539.27354-1-willy@infradead.orgSigned-off-by: NMatthew Wilcox <mawilcox@microsoft.com>
      Acked-by: NKees Cook <keescook@chromium.org>
      Cc: Ingo Molnar <mingo@kernel.org>
      Cc: Josh Poimboeuf <jpoimboe@redhat.com>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      a3d6c976
    • A
      proc: fix coredump vs read /proc/*/stat race · 8bb2ee19
      Alexey Dobriyan 提交于
      do_task_stat() accesses IP and SP of a task without bumping reference
      count of a stack (which became an entity with independent lifetime at
      some point).
      
      Steps to reproduce:
      
          #include <stdio.h>
          #include <sys/types.h>
          #include <sys/stat.h>
          #include <fcntl.h>
          #include <sys/time.h>
          #include <sys/resource.h>
          #include <unistd.h>
          #include <sys/wait.h>
      
          int main(void)
          {
          	setrlimit(RLIMIT_CORE, &(struct rlimit){});
      
          	while (1) {
          		char buf[64];
          		char buf2[4096];
          		pid_t pid;
          		int fd;
      
          		pid = fork();
          		if (pid == 0) {
          			*(volatile int *)0 = 0;
          		}
      
          		snprintf(buf, sizeof(buf), "/proc/%u/stat", pid);
          		fd = open(buf, O_RDONLY);
          		read(fd, buf2, sizeof(buf2));
          		close(fd);
      
          		waitpid(pid, NULL, 0);
          	}
          	return 0;
          }
      
          BUG: unable to handle kernel paging request at 0000000000003fd8
          IP: do_task_stat+0x8b4/0xaf0
          PGD 800000003d73e067 P4D 800000003d73e067 PUD 3d558067 PMD 0
          Oops: 0000 [#1] PREEMPT SMP PTI
          CPU: 0 PID: 1417 Comm: a.out Not tainted 4.15.0-rc8-dirty #2
          Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1.fc27 04/01/2014
          RIP: 0010:do_task_stat+0x8b4/0xaf0
          Call Trace:
           proc_single_show+0x43/0x70
           seq_read+0xe6/0x3b0
           __vfs_read+0x1e/0x120
           vfs_read+0x84/0x110
           SyS_read+0x3d/0xa0
           entry_SYSCALL_64_fastpath+0x13/0x6c
          RIP: 0033:0x7f4d7928cba0
          RSP: 002b:00007ffddb245158 EFLAGS: 00000246
          Code: 03 b7 a0 01 00 00 4c 8b 4c 24 70 4c 8b 44 24 78 4c 89 74 24 18 e9 91 f9 ff ff f6 45 4d 02 0f 84 fd f7 ff ff 48 8b 45 40 48 89 ef <48> 8b 80 d8 3f 00 00 48 89 44 24 20 e8 9b 97 eb ff 48 89 44 24
          RIP: do_task_stat+0x8b4/0xaf0 RSP: ffffc90000607cc8
          CR2: 0000000000003fd8
      
      John Ogness said: for my tests I added an else case to verify that the
      race is hit and correctly mitigated.
      
      Link: http://lkml.kernel.org/r/20180116175054.GA11513@avx2Signed-off-by: NAlexey Dobriyan <adobriyan@gmail.com>
      Reported-by: N"Kohli, Gaurav" <gkohli@codeaurora.org>
      Tested-by: NJohn Ogness <john.ogness@linutronix.de>
      Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
      Cc: Ingo Molnar <mingo@elte.hu>
      Cc: Oleg Nesterov <oleg@redhat.com>
      Cc: <stable@vger.kernel.org>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      8bb2ee19