[kernel-hardening] [RFC V2 4/6] lib: vsprintf: default kptr_restrict to the maximum value

From: Tobin C. Harding
Date: Sat Sep 30 2017 - 20:08:09 EST


Set the initial value of kptr_restrict to the maximum
setting rather than the minimum setting, to ensure that
early boot logging is not leaking information.

Signed-off-by: Tobin C. Harding <me@xxxxxxxx>
---
lib/vsprintf.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/vsprintf.c b/lib/vsprintf.c
index 0271223..e009325 100644
--- a/lib/vsprintf.c
+++ b/lib/vsprintf.c
@@ -396,7 +396,7 @@ struct printf_spec {
#define FIELD_WIDTH_MAX ((1 << 23) - 1)
#define PRECISION_MAX ((1 << 15) - 1)

-int kptr_restrict __read_mostly;
+int kptr_restrict __read_mostly = 4; /* maximum setting */

/*
* return non-zero if we should cleanse pointers for %p and %pK specifiers.
--
2.7.4