1. 29 Jan, 2024 2 commits
    • Qiuxu Zhuo's avatar
      x86/lib: Revert to _ASM_EXTABLE_UA() for {get,put}_user() fixups · 8eed4e00
      Qiuxu Zhuo authored
      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
      
        b19b74bc ("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
      
        6014bc27 ("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: b19b74bc ("x86/mm: Rework address range check in get_user() and put_user()")
      Signed-off-by: default avatarQiuxu Zhuo <qiuxu.zhuo@intel.com>
      Signed-off-by: default avatarBorislav Petkov (AMD) <bp@alien8.de>
      Reviewed-by: default avatarKirill A. Shutemov <kirill.shutemov@linux.intel.com>
      Cc: <stable@kernel.org>
      Link: https://lore.kernel.org/r/20240129063842.61584-1-qiuxu.zhuo@intel.com
      8eed4e00
    • Linus Torvalds's avatar
      Linux 6.8-rc2 · 41bccc98
      Linus Torvalds authored
      41bccc98
  2. 28 Jan, 2024 7 commits
  3. 27 Jan, 2024 9 commits
  4. 26 Jan, 2024 22 commits