linux-kernel - [PATCH 2/6] rtc: pcf8563 Fix write of invalid bits to ST2 reg

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Mon, 27 Oct 2014 15:16:57 +0100
From:	Jan Kardell <jan.kardell@...liq.com>
To:	Alessandro Zummo <a.zummo@...ertech.it>,
	rtc-linux@...glegroups.com, linux-kernel@...r.kernel.org
Cc:	Vincent Donnefort <vdonnefort@...il.com>,
	Dan Carpenter <dan.carpenter@...cle.com>
Subject: [PATCH 2/6] rtc: pcf8563 Fix write of invalid bits to ST2 reg

>From the NXP datasheet:
"Bits labeled as N should always be written with logic 0."

At least one of those bits is sometime read as a 1, therfore violating
this rule. To fix this we mask away those bits.

Signed-off-by: Jan Kardell <jan.kardell@...liq.com>
---
 drivers/rtc/rtc-pcf8563.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/rtc/rtc-pcf8563.c b/drivers/rtc/rtc-pcf8563.c
index 1a865c9..8c23606 100644
--- a/drivers/rtc/rtc-pcf8563.c
+++ b/drivers/rtc/rtc-pcf8563.c
@@ -28,6 +28,7 @@
 #define PCF8563_REG_ST2		0x01
 #define PCF8563_BIT_AIE		(1 << 1)
 #define PCF8563_BIT_AF		(1 << 3)
+#define PCF8563_BITS_ST2_N	(7 << 5)
 
 #define PCF8563_REG_SC		0x02 /* datetime */
 #define PCF8563_REG_MN		0x03
@@ -130,7 +131,7 @@ static int pcf8563_set_alarm_mode(struct i2c_client *client, bool on)
 	else
 		buf &= ~PCF8563_BIT_AIE;
 
-	buf &= ~PCF8563_BIT_AF;
+	buf &= ~(PCF8563_BIT_AF | PCF8563_BITS_ST2_N);
 
 	err = pcf8563_write_block_data(client, PCF8563_REG_ST2, 1, &buf);
 	if (err < 0) {
-- 
1.8.4.5

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/