Re: [PATCH v2] powerpc/mm: Fix set_memory_*() against concurrent accesses

On Wed, 18 Aug 2021 22:05:18 +1000, Michael Ellerman wrote:

Laurent reported that STRICT_MODULE_RWX was causing intermittent crashes
on one of his systems:

  kernel tried to execute exec-protected page (c008000004073278) - exploit attempt? (uid: 0)
  BUG: Unable to handle kernel instruction fetch
  Faulting instruction address: 0xc008000004073278
  Oops: Kernel access of bad area, sig: 11 [#1]
  LE PAGE_SIZE=64K MMU=Radix SMP NR_CPUS=2048 NUMA pSeries
  Modules linked in: drm virtio_console fuse drm_panel_orientation_quirks ...
  CPU: 3 PID: 44 Comm: kworker/3:1 Not tainted 5.14.0-rc4+ #12
  Workqueue: events control_work_handler [virtio_console]
  NIP:  c008000004073278 LR: c008000004073278 CTR: c0000000001e9de0
  REGS: c00000002e4ef7e0 TRAP: 0400   Not tainted  (5.14.0-rc4+)
  MSR:  800000004280b033 <SF,VEC,VSX,EE,FP,ME,IR,DR,RI,LE>  CR: 24002822 XER: 200400cf
  ...
  NIP fill_queue+0xf0/0x210 [virtio_console]
  LR  fill_queue+0xf0/0x210 [virtio_console]
  Call Trace:
    fill_queue+0xb4/0x210 [virtio_console] (unreliable)
    add_port+0x1a8/0x470 [virtio_console]
    control_work_handler+0xbc/0x1e8 [virtio_console]
    process_one_work+0x290/0x590
    worker_thread+0x88/0x620
    kthread+0x194/0x1a0
    ret_from_kernel_thread+0x5c/0x64

[...]

Applied to powerpc/fixes.

[1/1] powerpc/mm: Fix set_memory_*() against concurrent accesses
      https://git.kernel.org/powerpc/c/9f7853d7609d59172eecfc5e7ccf503bc1b690bd

cheers