x86/uaccess: instrument copy_from_user_nmi()

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@google.com
Signed-off-by: Alexander Potapenko <glider@google.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Marco Elver <elver@google.com>
Cc: Masahiro Yamada <masahiroy@kernel.org>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/arch/x86/lib/usercopy.c b/arch/x86/lib/usercopy.c
index f1bb186..24b48af 100644 (file)
--- a/arch/x86/lib/usercopy.c
+++ b/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 __user *from, unsigned long n)
         * 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;