[PATCH] powerpc/pseries: Whitelist dtl slub object for copying to userspace

[Michael Ellerman]

On Fri, 14 Jun 2024 23:08:44 +0530, Anjali K wrote:
> Reading the dispatch trace log from /sys/kernel/debug/powerpc/dtl/cpu-*
> results in a BUG() when the config CONFIG_HARDENED_USERCOPY is enabled as
> shown below.
> 
>     kernel BUG at mm/usercopy.c:102!
>     Oops: Exception in kernel mode, sig: 5 [#1]
>     LE PAGE_SIZE=64K MMU=Radix SMP NR_CPUS=2048 NUMA pSeries
>     Modules linked in: xfs libcrc32c dm_service_time sd_mod t10_pi sg ibmvfc
>     scsi_transport_fc ibmveth pseries_wdt dm_multipath dm_mirror dm_region_hash dm_log dm_mod fuse
>     CPU: 27 PID: 1815 Comm: python3 Not tainted 6.10.0-rc3 #85
>     Hardware name: IBM,9040-MRX POWER10 (raw) 0x800200 0xf000006 of:IBM,FW1060.00 (NM1060_042) hv:phyp pSeries
>     NIP:  c0000000005d23d4 LR: c0000000005d23d0 CTR: 00000000006ee6f8
>     REGS: c000000120c078c0 TRAP: 0700   Not tainted  (6.10.0-rc3)
>     MSR:  8000000000029033 <SF,EE,ME,IR,DR,RI,LE>  CR: 2828220f  XER: 0000000e
>     CFAR: c0000000001fdc80 IRQMASK: 0
>     [ ... GPRs omitted ... ]
>     NIP [c0000000005d23d4] usercopy_abort+0x78/0xb0
>     LR [c0000000005d23d0] usercopy_abort+0x74/0xb0
>     Call Trace:
>      usercopy_abort+0x74/0xb0 (unreliable)
>      __check_heap_object+0xf8/0x120
>      check_heap_object+0x218/0x240
>      __check_object_size+0x84/0x1a4
>      dtl_file_read+0x17c/0x2c4
>      full_proxy_read+0x8c/0x110
>      vfs_read+0xdc/0x3a0
>      ksys_read+0x84/0x144
>      system_call_exception+0x124/0x330
>      system_call_vectored_common+0x15c/0x2ec
>     --- interrupt: 3000 at 0x7fff81f3ab34
> 
> [...]

Applied to powerpc/fixes.

[1/1] powerpc/pseries: Whitelist dtl slub object for copying to userspace
      https://git.kernel.org/powerpc/c/1a14150e1656f7a332a943154fc486504db4d586

cheers