linux-kernel - [PATCH v2 2/2] rtc: ds1307: Clamp year to valid BCD (0-99) in `set

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]

Message-ID: <20240611072411.671600-2-csokas.bence@prolan.hu>
Date: Tue, 11 Jun 2024 09:24:09 +0200
From: Csókás, Bence <csokas.bence@...lan.hu>
To: <linux-rtc@...r.kernel.org>, <linux-kernel@...r.kernel.org>
CC: Csókás, Bence <csokas.bence@...lan.hu>,
	Szentendrei, Tamás <szentendrei.tamas@...lan.hu>,
	Alexandre Belloni <alexandre.belloni@...tlin.com>
Subject: [PATCH v2 2/2] rtc: ds1307: Clamp year to valid BCD (0-99) in `set_time()`

`tm_year` may go up to 299 if the device supports the
century bit. Therefore, subtracting may not give us
a valid 2-digit number, but modulo does.

Co-developed-by: Szentendrei, Tamás <szentendrei.tamas@...lan.hu>
Signed-off-by: Szentendrei, Tamás <szentendrei.tamas@...lan.hu>
Signed-off-by: Csókás, Bence <csokas.bence@...lan.hu>
---
 drivers/rtc/rtc-ds1307.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/rtc/rtc-ds1307.c b/drivers/rtc/rtc-ds1307.c
index bdb7b201a160..872e0b679be4 100644
--- a/drivers/rtc/rtc-ds1307.c
+++ b/drivers/rtc/rtc-ds1307.c
@@ -359,7 +359,7 @@ static int ds1307_set_time(struct device *dev, struct rtc_time *t)
 	regs[DS1307_REG_MONTH] = bin2bcd(t->tm_mon + 1);
 
 	/* assume 20YY not 19YY */
-	tmp = t->tm_year - 100;
+	tmp = t->tm_year % 100;
 	regs[DS1307_REG_YEAR] = bin2bcd(tmp);
 
 	if (chip->century_enable_bit)
-- 
2.34.1