1. 16 5月, 2018 1 次提交
    • S
      vsprintf: Replace memory barrier with static_key for random_ptr_key update · 85f4f12d
      Steven Rostedt (VMware) 提交于
      Reviewing Tobin's patches for getting pointers out early before
      entropy has been established, I noticed that there's a lone smp_mb() in
      the code. As with most lone memory barriers, this one appears to be
      incorrectly used.
      
      We currently basically have this:
      
      	get_random_bytes(&ptr_key, sizeof(ptr_key));
      	/*
      	 * have_filled_random_ptr_key==true is dependent on get_random_bytes().
      	 * ptr_to_id() needs to see have_filled_random_ptr_key==true
      	 * after get_random_bytes() returns.
      	 */
      	smp_mb();
      	WRITE_ONCE(have_filled_random_ptr_key, true);
      
      And later we have:
      
      	if (unlikely(!have_filled_random_ptr_key))
      		return string(buf, end, "(ptrval)", spec);
      
      /* Missing memory barrier here. */
      
      	hashval = (unsigned long)siphash_1u64((u64)ptr, &ptr_key);
      
      As the CPU can perform speculative loads, we could have a situation
      with the following:
      
      	CPU0				CPU1
      	----				----
      				   load ptr_key = 0
         store ptr_key = random
         smp_mb()
         store have_filled_random_ptr_key
      
      				   load have_filled_random_ptr_key = true
      
      				    BAD BAD BAD! (you're so bad!)
      
      Because nothing prevents CPU1 from loading ptr_key before loading
      have_filled_random_ptr_key.
      
      But this race is very unlikely, but we can't keep an incorrect smp_mb() in
      place. Instead, replace the have_filled_random_ptr_key with a static_branch
      not_filled_random_ptr_key, that is initialized to true and changed to false
      when we get enough entropy. If the update happens in early boot, the
      static_key is updated immediately, otherwise it will have to wait till
      entropy is filled and this happens in an interrupt handler which can't
      enable a static_key, as that requires a preemptible context. In that case, a
      work_queue is used to enable it, as entropy already took too long to
      establish in the first place waiting a little more shouldn't hurt anything.
      
      The benefit of using the static key is that the unlikely branch in
      vsprintf() now becomes a nop.
      
      Link: http://lkml.kernel.org/r/20180515100558.21df515e@gandalf.local.home
      
      Cc: stable@vger.kernel.org
      Fixes: ad67b74d ("printk: hash addresses printed with %p")
      Acked-by: NLinus Torvalds <torvalds@linux-foundation.org>
      Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>
      85f4f12d
  2. 14 5月, 2018 5 次提交
    • L
      Linux 4.17-rc5 · 67b8d5c7
      Linus Torvalds 提交于
      67b8d5c7
    • L
      Merge branch 'x86-pti-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip · 66e1c94d
      Linus Torvalds 提交于
      Pull x86/pti updates from Thomas Gleixner:
       "A mixed bag of fixes and updates for the ghosts which are hunting us.
      
        The scheduler fixes have been pulled into that branch to avoid
        conflicts.
      
         - A set of fixes to address a khread_parkme() race which caused lost
           wakeups and loss of state.
      
         - A deadlock fix for stop_machine() solved by moving the wakeups
           outside of the stopper_lock held region.
      
         - A set of Spectre V1 array access restrictions. The possible
           problematic spots were discuvered by Dan Carpenters new checks in
           smatch.
      
         - Removal of an unused file which was forgotten when the rest of that
           functionality was removed"
      
      * 'x86-pti-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
        x86/vdso: Remove unused file
        perf/x86/cstate: Fix possible Spectre-v1 indexing for pkg_msr
        perf/x86/msr: Fix possible Spectre-v1 indexing in the MSR driver
        perf/x86: Fix possible Spectre-v1 indexing for x86_pmu::event_map()
        perf/x86: Fix possible Spectre-v1 indexing for hw_perf_event cache_*
        perf/core: Fix possible Spectre-v1 indexing for ->aux_pages[]
        sched/autogroup: Fix possible Spectre-v1 indexing for sched_prio_to_weight[]
        sched/core: Fix possible Spectre-v1 indexing for sched_prio_to_weight[]
        sched/core: Introduce set_special_state()
        kthread, sched/wait: Fix kthread_parkme() completion issue
        kthread, sched/wait: Fix kthread_parkme() wait-loop
        sched/fair: Fix the update of blocked load when newly idle
        stop_machine, sched: Fix migrate_swap() vs. active_balance() deadlock
      66e1c94d
    • L
      Merge branch 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip · 86a4ac43
      Linus Torvalds 提交于
      Pull scheduler fix from Thomas Gleixner:
       "Revert the new NUMA aware placement approach which turned out to
        create more problems than it solved"
      
      * 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
        Revert "sched/numa: Delay retrying placement for automatic NUMA balance after wake_affine()"
      86a4ac43
    • L
      Merge branch 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip · baeda713
      Linus Torvalds 提交于
      Pull perf tooling fixes from Thomas Gleixner:
       "Another small set of perf tooling fixes and updates:
      
         - Revert "perf pmu: Fix pmu events parsing rule", as it broke Intel
           PT event description parsing (Arnaldo Carvalho de Melo)
      
         - Sync x86's cpufeatures.h and kvm UAPI headers with the kernel
           sources, suppressing the ABI drift warnings (Arnaldo Carvalho de
           Melo)
      
         - Remove duplicated entry for westmereep-dp in Intel's mapfile.csv
           (William Cohen)
      
         - Fix typo in 'perf bench numa' options description (Yisheng Xie)"
      
      * 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
        Revert "perf pmu: Fix pmu events parsing rule"
        tools headers kvm: Sync ARM UAPI headers with the kernel sources
        tools headers kvm: Sync uapi/linux/kvm.h with the kernel sources
        tools headers: Sync x86 cpufeatures.h with the kernel sources
        perf vendor events intel: Remove duplicated entry for westmereep-dp in mapfile.csv
        perf bench numa: Fix typo in options
      baeda713
    • L
      Merge tag 'dma-mapping-4.17-5' of git://git.infradead.org/users/hch/dma-mapping · 0503fd65
      Linus Torvalds 提交于
      Pull dma-mapping fix from Christoph Hellwig:
       "Just one little fix from Jean to avoid a harmless but very annoying
        warning, especially for the drm code"
      
      * tag 'dma-mapping-4.17-5' of git://git.infradead.org/users/hch/dma-mapping:
        swiotlb: silent unwanted warning "buffer is full"
      0503fd65
  3. 13 5月, 2018 3 次提交
  4. 12 5月, 2018 31 次提交