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

[Michael Ellerman]

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