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Qiuxu Zhuo 8eed4e00a3 x86/lib: Revert to _ASM_EXTABLE_UA() for {get,put}_user() fixups 
During memory error injection test on kernels >= v6.4, the kernel panics
like below. However, this issue couldn't be reproduced on kernels <= v6.3.

  mce: [Hardware Error]: CPU 296: Machine Check Exception: f Bank 1: bd80000000100134
  mce: [Hardware Error]: RIP 10:<ffffffff821b9776> {__get_user_nocheck_4+0x6/0x20}
  mce: [Hardware Error]: TSC 411a93533ed ADDR 346a8730040 MISC 86
  mce: [Hardware Error]: PROCESSOR 0:a06d0 TIME 1706000767 SOCKET 1 APIC 211 microcode 80001490
  mce: [Hardware Error]: Run the above through 'mcelog --ascii'
  mce: [Hardware Error]: Machine check: Data load in unrecoverable area of kernel
  Kernel panic - not syncing: Fatal local machine check

The MCA code can recover from an in-kernel #MC if the fixup type is
EX_TYPE_UACCESS, explicitly indicating that the kernel is attempting to
access userspace memory. However, if the fixup type is EX_TYPE_DEFAULT
the only thing that is raised for an in-kernel #MC is a panic.

ex_handler_uaccess() would warn if users gave a non-canonical addresses
(with bit 63 clear) to {get, put}_user(), which was unexpected.

Therefore, commit

  b19b74bc99 ("x86/mm: Rework address range check in get_user() and put_user()")

replaced _ASM_EXTABLE_UA() with _ASM_EXTABLE() for {get, put}_user()
fixups. However, the new fixup type EX_TYPE_DEFAULT results in a panic.

Commit

  6014bc2756 ("x86-64: make access_ok() independent of LAM")

added the check gp_fault_address_ok() right before the WARN_ONCE() in
ex_handler_uaccess() to not warn about non-canonical user addresses due
to LAM.

With that in place, revert back to _ASM_EXTABLE_UA() for {get,put}_user()
exception fixups in order to be able to handle in-kernel MCEs correctly
again.

  [ bp: Massage commit message. ]

Fixes: b19b74bc99 ("x86/mm: Rework address range check in get_user() and put_user()")
Signed-off-by: Qiuxu Zhuo <qiuxu.zhuo@intel.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: <stable@kernel.org>
Link: https://lore.kernel.org/r/20240129063842.61584-1-qiuxu.zhuo@intel.com
2024-01-29 11:40:41 +01:00
..
alpha RTC for 6.8 2024-01-18 17:25:39 -08:00
arc IOMMU Updates for Linux v6.8 2024-01-18 15:16:57 -08:00
arm Samsung fixes for v6.8 2024-01-25 18:23:10 +01:00
arm64 Samsung fixes for v6.8 2024-01-25 18:23:10 +01:00
csky vfs-6.8.netfs 2024-01-19 09:10:23 -08:00
hexagon asm-generic cleanups for 6.8 2024-01-10 18:13:44 -08:00
loongarch LoongArch: KVM: Add returns to SIMD stubs 2024-01-26 16:22:07 +08:00
m68k percpu: 2024-01-18 15:01:28 -08:00
microblaze Microblaze patches for 6.8-rc1 2024-01-17 11:27:23 -08:00
mips mips: Call lose_fpu(0) before initializing fcr31 in mips_set_personality_nan 2024-01-27 11:08:04 +01:00
nios2 percpu: 2024-01-18 15:01:28 -08:00
openrisc OpenRISC updates for 6.6 2023-09-05 10:09:31 -07:00
parisc percpu: 2024-01-18 15:01:28 -08:00
powerpc powerpc fixes for 6.8 #2 2024-01-21 11:04:29 -08:00
riscv Arm SoC fixes for 6.8, part 1 2024-01-26 13:09:38 -08:00
s390 vfs-6.8.netfs 2024-01-19 09:10:23 -08:00
sh sh updates for v6.8 2024-01-20 09:24:06 -08:00
sparc sparc: Use device_get_match_data() 2024-01-19 08:08:53 -06:00
um TTY/Serial changes for 6.8-rc1 2024-01-18 11:37:24 -08:00
x86 x86/lib: Revert to _ASM_EXTABLE_UA() for {get,put}_user() fixups 2024-01-29 11:40:41 +01:00
xtensa percpu: 2024-01-18 15:01:28 -08:00
.gitignore
Kconfig IOMMU Updates for Linux v6.8 2024-01-18 15:16:57 -08:00