Merge: x86/lib: Revert to _ASM_EXTABLE_UA() for {get,put}_user() fixups

MR: https://gitlab.com/redhat/centos-stream/src/kernel/centos-stream-9/-/merge_requests/4020

JIRA: https://issues.redhat.com/browse/RHEL-31441  
CVE: CVE-2024-26674  
  
Build Info: https://brewweb.engineering.redhat.com/brew/taskinfo?taskID=60431479  
  
Tested: Did sanity boot testing using Intel (intel-birchstream-gnr-ap-01) system.  
  
commit 8eed4e0  
Author: Qiuxu Zhuo <qiuxu.zhuo@intel.com>  
Date:   Mon Jan 29 14:38:42 2024 +0800  
  
    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  
  
      b19b74b ("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  
  
      6014bc2 ("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: b19b74b ("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  
  
Signed-off-by: Steve Best <sbest@redhat.com>

Approved-by: Tony Camuso <tcamuso@redhat.com>
Approved-by: Lenny Szubowicz <lszubowi@redhat.com>
Approved-by: David Arcari <darcari@redhat.com>
Approved-by: CKI KWF Bot <cki-ci-bot+kwf-gitlab-com@redhat.com>

Merged-by: Lucas Zampieri <lzampier@redhat.com>

Author: zampierilucas

arch/x86/lib/getuser.S

@@ -163,23 +163,23 @@ SYM_CODE_END(__get_user_8_handle_exception)
 #endif
 
 /* get_user */
-	_ASM_EXTABLE(1b, __get_user_handle_exception)
-	_ASM_EXTABLE(2b, __get_user_handle_exception)
-	_ASM_EXTABLE(3b, __get_user_handle_exception)
+	_ASM_EXTABLE_UA(1b, __get_user_handle_exception)
+	_ASM_EXTABLE_UA(2b, __get_user_handle_exception)
+	_ASM_EXTABLE_UA(3b, __get_user_handle_exception)
 #ifdef CONFIG_X86_64
-	_ASM_EXTABLE(4b, __get_user_handle_exception)
+	_ASM_EXTABLE_UA(4b, __get_user_handle_exception)
 #else
-	_ASM_EXTABLE(4b, __get_user_8_handle_exception)
-	_ASM_EXTABLE(5b, __get_user_8_handle_exception)
+	_ASM_EXTABLE_UA(4b, __get_user_8_handle_exception)
+	_ASM_EXTABLE_UA(5b, __get_user_8_handle_exception)
 #endif
 
 /* __get_user */
-	_ASM_EXTABLE(6b, __get_user_handle_exception)
-	_ASM_EXTABLE(7b, __get_user_handle_exception)
-	_ASM_EXTABLE(8b, __get_user_handle_exception)
+	_ASM_EXTABLE_UA(6b, __get_user_handle_exception)
+	_ASM_EXTABLE_UA(7b, __get_user_handle_exception)
+	_ASM_EXTABLE_UA(8b, __get_user_handle_exception)
 #ifdef CONFIG_X86_64
-	_ASM_EXTABLE(9b, __get_user_handle_exception)
+	_ASM_EXTABLE_UA(9b, __get_user_handle_exception)
 #else
-	_ASM_EXTABLE(9b, __get_user_8_handle_exception)
-	_ASM_EXTABLE(10b, __get_user_8_handle_exception)
+	_ASM_EXTABLE_UA(9b, __get_user_8_handle_exception)
+	_ASM_EXTABLE_UA(10b, __get_user_8_handle_exception)
 #endif

arch/x86/lib/putuser.S

@@ -134,15 +134,15 @@ SYM_CODE_START_LOCAL(__put_user_handle_exception)
 	RET
 SYM_CODE_END(__put_user_handle_exception)
 
-	_ASM_EXTABLE(1b, __put_user_handle_exception)
-	_ASM_EXTABLE(2b, __put_user_handle_exception)
-	_ASM_EXTABLE(3b, __put_user_handle_exception)
-	_ASM_EXTABLE(4b, __put_user_handle_exception)
-	_ASM_EXTABLE(5b, __put_user_handle_exception)
-	_ASM_EXTABLE(6b, __put_user_handle_exception)
-	_ASM_EXTABLE(7b, __put_user_handle_exception)
-	_ASM_EXTABLE(9b, __put_user_handle_exception)
+	_ASM_EXTABLE_UA(1b, __put_user_handle_exception)
+	_ASM_EXTABLE_UA(2b, __put_user_handle_exception)
+	_ASM_EXTABLE_UA(3b, __put_user_handle_exception)
+	_ASM_EXTABLE_UA(4b, __put_user_handle_exception)
+	_ASM_EXTABLE_UA(5b, __put_user_handle_exception)
+	_ASM_EXTABLE_UA(6b, __put_user_handle_exception)
+	_ASM_EXTABLE_UA(7b, __put_user_handle_exception)
+	_ASM_EXTABLE_UA(9b, __put_user_handle_exception)
 #ifdef CONFIG_X86_32
-	_ASM_EXTABLE(8b, __put_user_handle_exception)
-	_ASM_EXTABLE(10b, __put_user_handle_exception)
+	_ASM_EXTABLE_UA(8b, __put_user_handle_exception)
+	_ASM_EXTABLE_UA(10b, __put_user_handle_exception)
 #endif