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Anjali K 94492bf3bb powerpc/pseries: Whitelist dtl slub object for copying to userspace 
[ Upstream commit 1a14150e1656f7a332a943154fc486504db4d586 ]

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

Commit 6d07d1cd300f ("usercopy: Restrict non-usercopy caches to size 0")
requires that only whitelisted areas in slab/slub objects can be copied to
userspace when usercopy hardening is enabled using CONFIG_HARDENED_USERCOPY.
Dtl contains hypervisor dispatch events which are expected to be read by
privileged users. Hence mark this safe for user access.
Specify useroffset=0 and usersize=DISPATCH_LOG_BYTES to whitelist the
entire object.

Co-developed-by: Vishal Chourasia <vishalc@linux.ibm.com>
Signed-off-by: Vishal Chourasia <vishalc@linux.ibm.com>
Signed-off-by: Anjali K <anjalik@linux.ibm.com>
Reviewed-by: Srikar Dronamraju <srikar@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20240614173844.746818-1-anjalik@linux.ibm.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
2024-11-19 14:19:50 +01:00
..
4xx Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
8xx Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
40x Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
44x powerpc/44x: select I2C for CURRITUCK 2024-11-18 12:12:19 +01:00
52xx Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
82xx Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
83xx Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
85xx Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
86xx Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
512x Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
amigaone Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
cell file: Rename fcheck lookup_fd_rcu 2024-11-19 12:27:27 +01:00
chrp Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
embedded6xx powerpc/embedded6xx: Fix no previous prototype for avr_uart_send() etc. 2024-11-19 08:44:55 +01:00
maple Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
pasemi Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
powermac Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
powernv powerpc/powernv: Add a null pointer check in opal_powercap_init() 2024-11-18 12:12:20 +01:00
ps3 Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
pseries powerpc/pseries: Whitelist dtl slub object for copying to userspace 2024-11-19 14:19:50 +01:00
fsl_uli1575.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
Kconfig Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
Kconfig.cputype Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
Makefile Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00