The patch titled
Subject: x86/uaccess: instrument copy_from_user_nmi()
has been added to the -mm mm-hotfixes-unstable branch. Its filename is
x86-uaccess-instrument-copy_from_user_nmi.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/x86-uaccess-instrument-copy_from_user_nmi.patch
This patch will later appear in the mm-hotfixes-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Alexander Potapenko <glider@xxxxxxxxxx>
Subject: x86/uaccess: instrument copy_from_user_nmi()
Date: Wed, 2 Nov 2022 12:06:08 +0100
Make sure usercopy hooks from linux/instrumented.h are invoked for
copy_from_user_nmi(). This fixes KMSAN false positives reported when
dumping opcodes for a stack trace.
Link: https://lkml.kernel.org/r/20221102110611.1085175-2-glider@xxxxxxxxxx
Signed-off-by: Alexander Potapenko <glider@xxxxxxxxxx>
Acked-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Cc: Kees Cook <keescook@xxxxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Marco Elver <elver@xxxxxxxxxx>
Cc: Masahiro Yamada <masahiroy@xxxxxxxxxx>
Cc: Nick Desaulniers <ndesaulniers@xxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
arch/x86/lib/usercopy.c | 3 +++
1 file changed, 3 insertions(+)
--- a/arch/x86/lib/usercopy.c~x86-uaccess-instrument-copy_from_user_nmi
+++ a/arch/x86/lib/usercopy.c
@@ -6,6 +6,7 @@
#include <linux/uaccess.h>
#include <linux/export.h>
+#include <linux/instrumented.h>
#include <asm/tlbflush.h>
@@ -44,7 +45,9 @@ copy_from_user_nmi(void *to, const void
* called from other contexts.
*/
pagefault_disable();
+ instrument_copy_from_user_before(to, from, n);
ret = raw_copy_from_user(to, from, n);
+ instrument_copy_from_user_after(to, from, n, ret);
pagefault_enable();
return ret;
_
Patches currently in -mm which might be from glider@xxxxxxxxxx are
kmsan-core-kmsan_in_runtime-should-return-true-in-nmi-context.patch
x86-uaccess-instrument-copy_from_user_nmi.patch
kconfigdebug-ensure-early-check-for-kmsan-in-config_kmsan_warn.patch
kmsan-make-sure-preempt_rt-is-off.patch
x86-traps-avoid-kmsan-bugs-originating-from-handle_bug.patch
