This is a note to let you know that I've just added the patch titled
x86/lib: Revert to _ASM_EXTABLE_UA() for {get,put}_user() fixups
to the 6.7-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
x86-lib-revert-to-_asm_extable_ua-for-get-put-_user-fixups.patch
and it can be found in the queue-6.7 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 8eed4e00a370b37b4e5985ed983dccedd555ea9d Mon Sep 17 00:00:00 2001
From: Qiuxu Zhuo <qiuxu.zhuo@xxxxxxxxx>
Date: Mon, 29 Jan 2024 14:38:42 +0800
Subject: x86/lib: Revert to _ASM_EXTABLE_UA() for {get,put}_user() fixups
From: Qiuxu Zhuo <qiuxu.zhuo@xxxxxxxxx>
commit 8eed4e00a370b37b4e5985ed983dccedd555ea9d upstream.
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
b19b74bc99b1 ("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
6014bc27561f ("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: b19b74bc99b1 ("x86/mm: Rework address range check in get_user() and put_user()")
Signed-off-by: Qiuxu Zhuo <qiuxu.zhuo@xxxxxxxxx>
Signed-off-by: Borislav Petkov (AMD) <bp@xxxxxxxxx>
Reviewed-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Cc: <stable@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20240129063842.61584-1-qiuxu.zhuo@xxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/x86/lib/getuser.S | 24 ++++++++++++------------
arch/x86/lib/putuser.S | 20 ++++++++++----------
2 files changed, 22 insertions(+), 22 deletions(-)
--- a/arch/x86/lib/getuser.S
+++ b/arch/x86/lib/getuser.S
@@ -163,23 +163,23 @@ SYM_CODE_END(__get_user_8_handle_excepti
#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
--- a/arch/x86/lib/putuser.S
+++ b/arch/x86/lib/putuser.S
@@ -133,15 +133,15 @@ SYM_CODE_START_LOCAL(__put_user_handle_e
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
Patches currently in stable-queue which might be from qiuxu.zhuo@xxxxxxxxx are
queue-6.7/x86-lib-revert-to-_asm_extable_ua-for-get-put-_user-fixups.patch
