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

From	"Tobin C. Harding" <me@tobin.cc>
Newsgroups	linux.kernel
Subject	[kernel-hardening] [RFC V2 4/6] lib: vsprintf: default kptr_restrict to the maximum value
Date	2017-10-01 02:10 +0200
Message-ID	<uvzZv-2ZT-7@gated-at.bofh.it> (permalink)
References	<uvzZv-2ZT-3@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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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@tobin.cc>
---
 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

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[kernel-hardening] [RFC V2 4/6] lib: vsprintf: default kptr_restrict to the maximum value "Tobin C. Harding" <me@tobin.cc> - 2017-10-01 02:10 +0200

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