linux-kernel - [PATCH] RTC: rtc_time_to_tm: use unsigned arithmetic

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-next>] [day] [month] [year] [list]

Message-ID: <Pine.LNX.4.55.0805062315530.16173@cliff.in.clinika.pl>
Date:	Tue, 6 May 2008 23:31:30 +0100 (BST)
From:	"Maciej W. Rozycki" <macro@...ux-mips.org>
To:	Alessandro Zummo <a.zummo@...ertech.it>,
	Andrew Morton <akpm@...ux-foundation.org>
cc:	rtc-linux@...glegroups.com, linux-kernel@...r.kernel.org
Subject: [PATCH] RTC: rtc_time_to_tm: use unsigned arithmetic

 The input argument to rtc_time_to_tm() is unsigned as well as are members
of the output structure.  However signed arithmetic is used within for
calculations leading to incorrect results for input values outside the
signed positive range.  If this happens the time of day returned is out of
range.

 Found the problem when fiddling with the RTC and the driver where year
was set to an unexpectedly large value like 2070, e.g.:

rtc0: setting system clock to 2070-01-01 1193046:71582832:26 UTC (3155760954)

while it should be:

rtc0: setting system clock to 2070-01-01 00:15:54 UTC (3155760954)

Changing types to unsigned fixes the problem.

Signed-off-by: Maciej W. Rozycki <macro@...ux-mips.org>
---
 Tested on 64-bit MIPS.  Please apply.

  Maciej

patch-2.6.26-rc1-20080505-rtc-time-unsigned-11
diff -up --recursive --new-file linux-2.6.26-rc1-20080505.macro/drivers/rtc/rtc-lib.c linux-2.6.26-rc1-20080505/drivers/rtc/rtc-lib.c
--- linux-2.6.26-rc1-20080505.macro/drivers/rtc/rtc-lib.c	2007-07-10 04:56:26.000000000 +0000
+++ linux-2.6.26-rc1-20080505/drivers/rtc/rtc-lib.c	2008-05-05 02:37:38.000000000 +0000
@@ -51,7 +51,7 @@ EXPORT_SYMBOL(rtc_year_days);
  */
 void rtc_time_to_tm(unsigned long time, struct rtc_time *tm)
 {
-	register int days, month, year;
+	register unsigned int days, month, year;
 
 	days = time / 86400;
 	time -= days * 86400;
--
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/