linux-kernel - [PATCH] vsprintf: kptr_restrict is okay in IRQ when 2

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Date:	Fri,  5 Feb 2016 14:45:21 +0100
From:	"Jason A. Donenfeld" <Jason@...c4.com>
To:	akpm@...ux-foundation.org, keescook@...omium.org,
	linux-kernel@...r.kernel.org
Cc:	"Jason A. Donenfeld" <Jason@...c4.com>
Subject: [PATCH] vsprintf: kptr_restrict is okay in IRQ when 2

The kptr_restrict flag, when set to 1, only prints the kernel
address when the user has CAP_SYSLOG. When it is set to 2, the
kernel address is always printed as zero. When set to 1, this
needs to check whether or not we're in IRQ. However, when set to
2, this check is unneccessary, and produces confusing results
in dmesg. Thus, only make sure we're not in IRQ when mode 1 is
used, but not mode 2.

Signed-off-by: Jason A. Donenfeld <Jason@...c4.com>
---
 lib/vsprintf.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/lib/vsprintf.c b/lib/vsprintf.c
index 80d8ce5..fab875f 100644
--- a/lib/vsprintf.c
+++ b/lib/vsprintf.c
@@ -1609,8 +1609,8 @@ char *pointer(const char *fmt, char *buf, char *end, void *ptr,
 		 * %pK cannot be used in IRQ context because its test
 		 * for CAP_SYSLOG would be meaningless.
 		 */
-		if (kptr_restrict && (in_irq() || in_serving_softirq() ||
-				      in_nmi())) {
+		if (kptr_restrict == 1 && (in_irq() || in_serving_softirq() ||
+				           in_nmi())) {
 			if (spec.field_width == -1)
 				spec.field_width = default_width;
 			return string(buf, end, "pK-error", spec);
-- 
2.7.0