kernel.git/arch/x86/kernel, branch linux-4.11.y

x86/mm/pat: Don't report PAT on CPUs that don't support it

2017-07-15T11:04:41Z

commit 99c13b8c8896d7bcb92753bf0c63a8de4326e78d upstream. The pat_enabled() logic is broken on CPUs which do not support PAT and where the initialization code fails to call pat_init(). Due to that the enabled flag stays true and pat_enabled() returns true wrongfully. As a consequence the mappings, e.g. for Xorg, are set up with the wrong caching mode and the required MTRR setups are omitted. To cure this the following changes are required: 1) Make pat_enabled() return true only if PAT initialization was invoked and successful. 2) Invoke init_cache_modes() unconditionally in setup_arch() and remove the extra callsites in pat_disable() and the pat disabled code path in pat_init(). Also rename __pat_enabled to pat_disabled to reflect the real purpose of this variable. Fixes: 9cd25aac1f44 ("x86/mm/pat: Emulate PAT when it is disabled") Signed-off-by: Mikulas Patocka Signed-off-by: Thomas Gleixner Cc: Bernhard Held Cc: Denys Vlasenko Cc: Peter Zijlstra Cc: Brian Gerst Cc: "Luis R. Rodriguez" Cc: Borislav Petkov Cc: Andy Lutomirski Cc: Josh Poimboeuf Cc: Andrew Morton Cc: Linus Torvalds Link: http://lkml.kernel.org/r/alpine.LRH.2.02.1707041749300.3456@file01.intranet.prod.int.rdu2.redhat.com Signed-off-by: Greg Kroah-Hartman

x86/intel_rdt: Fix memory leak on mount failure

2017-07-05T12:41:39Z

commit 79298acc4ba097e9ab78644e3e38902d73547c92 upstream. If mount fails, the kn_info directory is not freed causing memory leak. Add the missing error handling path. Fixes: 4e978d06dedb ("x86/intel_rdt: Add "info" files to resctrl file system") Signed-off-by: Vikas Shivappa Signed-off-by: Thomas Gleixner Cc: ravi.v.shankar@intel.com Cc: tony.luck@intel.com Cc: fenghua.yu@intel.com Cc: peterz@infradead.org Cc: vikas.shivappa@intel.com Cc: andi.kleen@intel.com Link: http://lkml.kernel.org/r/1498503368-20173-3-git-send-email-vikas.shivappa@linux.intel.com Signed-off-by: Greg Kroah-Hartman

mm: larger stack guard gap, between vmas

2017-06-24T05:06:22Z

commit 1be7107fbe18eed3e319a6c3e83c78254b693acb upstream. Stack guard page is a useful feature to reduce a risk of stack smashing into a different mapping. We have been using a single page gap which is sufficient to prevent having stack adjacent to a different mapping. But this seems to be insufficient in the light of the stack usage in userspace. E.g. glibc uses as large as 64kB alloca() in many commonly used functions. Others use constructs liks gid_t buffer[NGROUPS_MAX] which is 256kB or stack strings with MAX_ARG_STRLEN. This will become especially dangerous for suid binaries and the default no limit for the stack size limit because those applications can be tricked to consume a large portion of the stack and a single glibc call could jump over the guard page. These attacks are not theoretical, unfortunatelly. Make those attacks less probable by increasing the stack guard gap to 1MB (on systems with 4k pages; but make it depend on the page size because systems with larger base pages might cap stack allocations in the PAGE_SIZE units) which should cover larger alloca() and VLA stack allocations. It is obviously not a full fix because the problem is somehow inherent, but it should reduce attack space a lot. One could argue that the gap size should be configurable from userspace, but that can be done later when somebody finds that the new 1MB is wrong for some special case applications. For now, add a kernel command line option (stack_guard_gap) to specify the stack gap size (in page units). Implementation wise, first delete all the old code for stack guard page: because although we could get away with accounting one extra page in a stack vma, accounting a larger gap can break userspace - case in point, a program run with "ulimit -S -v 20000" failed when the 1MB gap was counted for RLIMIT_AS; similar problems could come with RLIMIT_MLOCK and strict non-overcommit mode. Instead of keeping gap inside the stack vma, maintain the stack guard gap as a gap between vmas: using vm_start_gap() in place of vm_start (or vm_end_gap() in place of vm_end if VM_GROWSUP) in just those few places which need to respect the gap - mainly arch_get_unmapped_area(), and and the vma tree's subtree_gap support for that. Original-patch-by: Oleg Nesterov Original-patch-by: Michal Hocko Signed-off-by: Hugh Dickins Acked-by: Michal Hocko Tested-by: Helge Deller # parisc Signed-off-by: Linus Torvalds [wt: backport to 4.11: adjust context] Signed-off-by: Willy Tarreau Signed-off-by: Greg Kroah-Hartman

x86/microcode/intel: Clear patch pointer before jettisoning the initrd

2017-06-14T13:07:49Z

commit 5b0bc9ac2ce4881ee318a21f31140584ce4dbdad upstream. During early boot, load_ucode_intel_ap() uses __load_ucode_intel() to obtain a pointer to the relevant microcode patch (embedded in the initrd), and stores this value in 'intel_ucode_patch' to speed up the microcode patch application for subsequent CPUs. On resuming from suspend-to-RAM, however, load_ucode_ap() calls load_ucode_intel_ap() for each non-boot-CPU. By then the initramfs is long gone so the pointer stored in 'intel_ucode_patch' no longer points to a valid microcode patch. Clear that pointer so that we effectively fall back to the CPU hotplug notifier callbacks to update the microcode. Signed-off-by: Dominik Brodowski [ Edit and massage commit message. ] Signed-off-by: Borislav Petkov Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/20170607095819.9754-1-bp@alien8.de Signed-off-by: Ingo Molnar Signed-off-by: Greg Kroah-Hartman

kvm: async_pf: fix rcu_irq_enter() with irqs enabled

2017-06-14T13:07:39Z

commit bbaf0e2b1c1b4f88abd6ef49576f0efb1734eae5 upstream. native_safe_halt enables interrupts, and you just shouldn't call rcu_irq_enter() with interrupts enabled. Reorder the call with the following local_irq_disable() to respect the invariant. Reported-by: Ross Zwisler Signed-off-by: Paolo Bonzini Acked-by: Paul E. McKenney Tested-by: Wanpeng Li Signed-off-by: Radim Krčmář Signed-off-by: Greg Kroah-Hartman

x86/MCE: Export memory_error()

2017-06-07T10:10:07Z

commit 2d1f406139ec20320bf38bcd2461aa8e358084b5 upstream. Export the function which checks whether an MCE is a memory error to other users so that we can reuse the logic. Drop the boot_cpu_data use, while at it, as mce.cpuvendor already has the CPU vendor in there. Integrate a piece from a patch from Vishal Verma to export it for modules (nfit). The main reason we're exporting it is that the nfit handler nfit_handle_mce() needs to detect a memory error properly before doing its recovery actions. Signed-off-by: Borislav Petkov Cc: Tony Luck Cc: Vishal Verma Link: http://lkml.kernel.org/r/20170519093915.15413-2-bp@alien8.de Signed-off-by: Thomas Gleixner Signed-off-by: Greg Kroah-Hartman

KVM: x86: Fix load damaged SSEx MXCSR register

2017-05-25T13:46:13Z

commit a575813bfe4bc15aba511a5e91e61d242bff8b9d upstream. Reported by syzkaller: BUG: unable to handle kernel paging request at ffffffffc07f6a2e IP: report_bug+0x94/0x120 PGD 348e12067 P4D 348e12067 PUD 348e14067 PMD 3cbd84067 PTE 80000003f7e87161 Oops: 0003 [#1] SMP CPU: 2 PID: 7091 Comm: kvm_load_guest_ Tainted: G OE 4.11.0+ #8 task: ffff92fdfb525400 task.stack: ffffbda6c3d04000 RIP: 0010:report_bug+0x94/0x120 RSP: 0018:ffffbda6c3d07b20 EFLAGS: 00010202 do_trap+0x156/0x170 do_error_trap+0xa3/0x170 ? kvm_load_guest_fpu.part.175+0x12a/0x170 [kvm] ? mark_held_locks+0x79/0xa0 ? retint_kernel+0x10/0x10 ? trace_hardirqs_off_thunk+0x1a/0x1c do_invalid_op+0x20/0x30 invalid_op+0x1e/0x30 RIP: 0010:kvm_load_guest_fpu.part.175+0x12a/0x170 [kvm] ? kvm_load_guest_fpu.part.175+0x1c/0x170 [kvm] kvm_arch_vcpu_ioctl_run+0xed6/0x1b70 [kvm] kvm_vcpu_ioctl+0x384/0x780 [kvm] ? kvm_vcpu_ioctl+0x384/0x780 [kvm] ? sched_clock+0x13/0x20 ? __do_page_fault+0x2a0/0x550 do_vfs_ioctl+0xa4/0x700 ? up_read+0x1f/0x40 ? __do_page_fault+0x2a0/0x550 SyS_ioctl+0x79/0x90 entry_SYSCALL_64_fastpath+0x23/0xc2 SDM mentioned that "The MXCSR has several reserved bits, and attempting to write a 1 to any of these bits will cause a general-protection exception(#GP) to be generated". The syzkaller forks' testcase overrides xsave area w/ random values and steps on the reserved bits of MXCSR register. The damaged MXCSR register values of guest will be restored to SSEx MXCSR register before vmentry. This patch fixes it by catching userspace override MXCSR register reserved bits w/ random values and bails out immediately. Reported-by: Andrey Konovalov Reviewed-by: Paolo Bonzini Cc: Paolo Bonzini Cc: Radim Krčmář Signed-off-by: Wanpeng Li Signed-off-by: Radim Krčmář Signed-off-by: Greg Kroah-Hartman

Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2017-04-30T18:44:18Z

Pull x86 fixes from Thomas Gleixner: "The final fixes for 4.11: - prevent a triple fault with function graph tracing triggered via suspend to ram - prevent optimizing for size when function graph tracing is enabled and the compiler does not support -mfentry - prevent mwaitx() being called with a zero timeout as mwaitx() might never return. Observed on the new Ryzen CPUs" * 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: Prevent timer value 0 for MWAITX x86/build: convert function graph '-Os' error to warning ftrace/x86: Fix triple fault with graph tracing and suspend-to-ram

x86/build: convert function graph '-Os' error to warning

2017-04-19T07:57:23Z

For pre-4.6.0 versions of GCC, which don't have '-mfentry', the '-maccumulate-outgoing-args' option is required for function graph tracing in order to avoid GCC bug 42109. However, GCC ignores '-maccumulate-outgoing-args' when '-Os' is also set. Currently we force a build error to prevent that scenario, but that breaks randconfigs. So change the error to a warning which also disables CONFIG_CC_OPTIMIZE_FOR_SIZE. Reported-by: Andi Kleen Signed-off-by: Josh Poimboeuf Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Steven Rostedt Cc: Thomas Gleixner Cc: kbuild test robot Cc: kbuild-all@01.org Link: http://lkml.kernel.org/r/20170418214429.o7fbwbmf4nqosezy@treble Signed-off-by: Ingo Molnar

x86/mce: Make the MCE notifier a blocking one

2017-04-18T20:23:48Z

The NFIT MCE handler callback (for handling media errors on NVDIMMs) takes a mutex to add the location of a memory error to a list. But since the notifier call chain for machine checks (x86_mce_decoder_chain) is atomic, we get a lockdep splat like: BUG: sleeping function called from invalid context at kernel/locking/mutex.c:620 in_atomic(): 1, irqs_disabled(): 0, pid: 4, name: kworker/0:0 [..] Call Trace: dump_stack ___might_sleep __might_sleep mutex_lock_nested ? __lock_acquire nfit_handle_mce notifier_call_chain atomic_notifier_call_chain ? atomic_notifier_call_chain mce_gen_pool_process Convert the notifier to a blocking one which gets to run only in process context. Boris: remove the notifier call in atomic context in print_mce(). For now, let's print the MCE on the atomic path so that we can make sure they go out and get logged at least. Fixes: 6839a6d96f4e ("nfit: do an ARS scrub on hitting a latent media error") Reported-by: Ross Zwisler Signed-off-by: Vishal Verma Acked-by: Tony Luck Cc: Dan Williams Cc: linux-edac Cc: x86-ml Cc: Link: http://lkml.kernel.org/r/20170411224457.24777-1-vishal.l.verma@intel.com Signed-off-by: Borislav Petkov Signed-off-by: Thomas Gleixner