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  1. Feb 18, 2022
  2. Feb 04, 2022
    • Kees Cook's avatar
      gcc-plugins/stackleak: Use noinstr in favor of notrace · dcb85f85
      Kees Cook authored
      
      While the stackleak plugin was already using notrace, objtool is now a
      bit more picky.  Update the notrace uses to noinstr.  Silences the
      following objtool warnings when building with:
      
      CONFIG_DEBUG_ENTRY=y
      CONFIG_STACK_VALIDATION=y
      CONFIG_VMLINUX_VALIDATION=y
      CONFIG_GCC_PLUGIN_STACKLEAK=y
      
        vmlinux.o: warning: objtool: do_syscall_64()+0x9: call to stackleak_track_stack() leaves .noinstr.text section
        vmlinux.o: warning: objtool: do_int80_syscall_32()+0x9: call to stackleak_track_stack() leaves .noinstr.text section
        vmlinux.o: warning: objtool: exc_general_protection()+0x22: call to stackleak_track_stack() leaves .noinstr.text section
        vmlinux.o: warning: objtool: fixup_bad_iret()+0x20: call to stackleak_track_stack() leaves .noinstr.text section
        vmlinux.o: warning: objtool: do_machine_check()+0x27: call to stackleak_track_stack() leaves .noinstr.text section
        vmlinux.o: warning: objtool: .text+0x5346e: call to stackleak_erase() leaves .noinstr.text section
        vmlinux.o: warning: objtool: .entry.text+0x143: call to stackleak_erase() leaves .noinstr.text section
        vmlinux.o: warning: objtool: .entry.text+0x10eb: call to stackleak_erase() leaves .noinstr.text section
        vmlinux.o: warning: objtool: .entry.text+0x17f9: call to stackleak_erase() leaves .noinstr.text section
      
      Note that the plugin's addition of calls to stackleak_track_stack() from
      noinstr functions is expected to be safe, as it isn't runtime
      instrumentation and is self-contained.
      
      Cc: Alexander Popov <alex.popov@linux.com>
      Suggested-by: default avatarPeter Zijlstra <peterz@infradead.org>
      Signed-off-by: default avatarKees Cook <keescook@chromium.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      dcb85f85
  3. Feb 03, 2022
    • Mickaël Salaün's avatar
      printk: Fix incorrect __user type in proc_dointvec_minmax_sysadmin() · 1f2cfdd3
      Mickaël Salaün authored
      The move of proc_dointvec_minmax_sysadmin() from kernel/sysctl.c to
      kernel/printk/sysctl.c introduced an incorrect __user attribute to the
      buffer argument.  I spotted this change in [1] as well as the kernel
      test robot.  Revert this change to please sparse:
      
        kernel/printk/sysctl.c:20:51: warning: incorrect type in argument 3 (different address spaces)
        kernel/printk/sysctl.c:20:51:    expected void *
        kernel/printk/sysctl.c:20:51:    got void [noderef] __user *buffer
      
      Fixes: faaa357a ("printk: move printk sysctl to printk/sysctl.c")
      Link: https://lore.kernel.org/r/20220104155024.48023-2-mic@digikod.net
      
       [1]
      Reported-by: default avatarkernel test robot <lkp@intel.com>
      Cc: Andrew Morton <akpm@linux-foundation.org>
      Cc: John Ogness <john.ogness@linutronix.de>
      Cc: Luis Chamberlain <mcgrof@kernel.org>
      Cc: Petr Mladek <pmladek@suse.com>
      Cc: Sergey Senozhatsky <senozhatsky@chromium.org>
      Cc: Steven Rostedt <rostedt@goodmis.org>
      Cc: Xiaoming Ni <nixiaoming@huawei.com>
      Signed-off-by: default avatarMickaël Salaün <mic@linux.microsoft.com>
      Link: https://lore.kernel.org/r/20220203145029.272640-1-mic@digikod.net
      
      
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      1f2cfdd3
    • Igor Pylypiv's avatar
      Revert "module, async: async_synchronize_full() on module init iff async is used" · 67d6212a
      Igor Pylypiv authored
      
      This reverts commit 774a1221.
      
      We need to finish all async code before the module init sequence is
      done.  In the reverted commit the PF_USED_ASYNC flag was added to mark a
      thread that called async_schedule().  Then the PF_USED_ASYNC flag was
      used to determine whether or not async_synchronize_full() needs to be
      invoked.  This works when modprobe thread is calling async_schedule(),
      but it does not work if module dispatches init code to a worker thread
      which then calls async_schedule().
      
      For example, PCI driver probing is invoked from a worker thread based on
      a node where device is attached:
      
      	if (cpu < nr_cpu_ids)
      		error = work_on_cpu(cpu, local_pci_probe, &ddi);
      	else
      		error = local_pci_probe(&ddi);
      
      We end up in a situation where a worker thread gets the PF_USED_ASYNC
      flag set instead of the modprobe thread.  As a result,
      async_synchronize_full() is not invoked and modprobe completes without
      waiting for the async code to finish.
      
      The issue was discovered while loading the pm80xx driver:
      (scsi_mod.scan=async)
      
      modprobe pm80xx                      worker
      ...
        do_init_module()
        ...
          pci_call_probe()
            work_on_cpu(local_pci_probe)
                                           local_pci_probe()
                                             pm8001_pci_probe()
                                               scsi_scan_host()
                                                 async_schedule()
                                                 worker->flags |= PF_USED_ASYNC;
                                           ...
            < return from worker >
        ...
        if (current->flags & PF_USED_ASYNC) <--- false
        	async_synchronize_full();
      
      Commit 21c3c5d2 ("block: don't request module during elevator init")
      fixed the deadlock issue which the reverted commit 774a1221
      ("module, async: async_synchronize_full() on module init iff async is
      used") tried to fix.
      
      Since commit 0fdff3ec ("async, kmod: warn on synchronous
      request_module() from async workers") synchronous module loading from
      async is not allowed.
      
      Given that the original deadlock issue is fixed and it is no longer
      allowed to call synchronous request_module() from async we can remove
      PF_USED_ASYNC flag to make module init consistently invoke
      async_synchronize_full() unless async module probe is requested.
      
      Signed-off-by: default avatarIgor Pylypiv <ipylypiv@google.com>
      Reviewed-by: default avatarChangyuan Lyu <changyuanl@google.com>
      Reviewed-by: default avatarLuis Chamberlain <mcgrof@kernel.org>
      Acked-by: default avatarTejun Heo <tj@kernel.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      67d6212a
    • Waiman Long's avatar
      cgroup/cpuset: Fix "suspicious RCU usage" lockdep warning · 2bdfd282
      Waiman Long authored
      
      It was found that a "suspicious RCU usage" lockdep warning was issued
      with the rcu_read_lock() call in update_sibling_cpumasks().  It is
      because the update_cpumasks_hier() function may sleep. So we have
      to release the RCU lock, call update_cpumasks_hier() and reacquire
      it afterward.
      
      Also add a percpu_rwsem_assert_held() in update_sibling_cpumasks()
      instead of stating that in the comment.
      
      Fixes: 4716909c ("cpuset: Track cpusets that use parent's effective_cpus")
      Signed-off-by: default avatarWaiman Long <longman@redhat.com>
      Tested-by: default avatarPhil Auld <pauld@redhat.com>
      Reviewed-by: default avatarPhil Auld <pauld@redhat.com>
      Signed-off-by: default avatarTejun Heo <tj@kernel.org>
      2bdfd282
    • Hou Tao's avatar
      bpf: Use VM_MAP instead of VM_ALLOC for ringbuf · b293dcc4
      Hou Tao authored
      
      After commit 2fd3fb0be1d1 ("kasan, vmalloc: unpoison VM_ALLOC pages
      after mapping"), non-VM_ALLOC mappings will be marked as accessible
      in __get_vm_area_node() when KASAN is enabled. But now the flag for
      ringbuf area is VM_ALLOC, so KASAN will complain out-of-bound access
      after vmap() returns. Because the ringbuf area is created by mapping
      allocated pages, so use VM_MAP instead.
      
      After the change, info in /proc/vmallocinfo also changes from
        [start]-[end]   24576 ringbuf_map_alloc+0x171/0x290 vmalloc user
      to
        [start]-[end]   24576 ringbuf_map_alloc+0x171/0x290 vmap user
      
      Fixes: 457f4436 ("bpf: Implement BPF ring buffer and verifier support for it")
      Reported-by: default avatar <syzbot+5ad567a418794b9b5983@syzkaller.appspotmail.com>
      Signed-off-by: default avatarHou Tao <houtao1@huawei.com>
      Signed-off-by: default avatarAndrii Nakryiko <andrii@kernel.org>
      Link: https://lore.kernel.org/bpf/20220202060158.6260-1-houtao1@huawei.com
      b293dcc4
  4. Feb 02, 2022
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