linux-kernel - [RFC v2c 4/8] fs: cifs: Make cnvrtDosUnixTm() y2038 safe

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Date:	Fri, 12 Feb 2016 01:52:49 -0800
From:	Deepa Dinamani <deepa.kernel@...il.com>
To:	linux-fsdevel@...r.kernel.org, y2038@...ts.linaro.org
Cc:	Arnd Bergmann <arnd@...db.de>, Dave Chinner <david@...morbit.com>,
	"Theodore Ts'o" <tytso@....edu>, linux-kernel@...r.kernel.org
Subject: [RFC v2c 4/8] fs: cifs: Make cnvrtDosUnixTm() y2038 safe

The seconds calculated from the server(DOS format)
cannot be saved in int data type as this cannot save
seconds since epoch after the year 2038.

Use long long for seconds field in cnvrtDosUnixTm(). This will
help represent 64 bit time even on 32 bit systems.

Note that even though the theoretical max on DOS times is 2107,
its api's only support until the year 2099. This means we can
get away with 32 bit unsigned sec field. But, the sec field uses
long long to maintain uniformity in the kernel, where everyone
uses the theoretical max.

Signed-off-by: Deepa Dinamani <deepa.kernel@...il.com>
---
 fs/cifs/netmisc.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/fs/cifs/netmisc.c b/fs/cifs/netmisc.c
index bf1b52e..ecbb7162 100644
--- a/fs/cifs/netmisc.c
+++ b/fs/cifs/netmisc.c
@@ -963,7 +963,8 @@ static const int total_days_of_prev_months[] = {
 struct timespec64 cnvrtDosUnixTm(__le16 le_date, __le16 le_time, int offset)
 {
 	struct timespec64 ts;
-	int sec, min, days, month, year;
+	long long sec;
+	int min, days, month, year;
 	u16 date = le16_to_cpu(le_date);
 	u16 time = le16_to_cpu(le_time);
 	SMB_TIME *st = (SMB_TIME *)&time;
@@ -974,7 +975,7 @@ struct timespec64 cnvrtDosUnixTm(__le16 le_date, __le16 le_time, int offset)
 	sec = 2 * st->TwoSeconds;
 	min = st->Minutes;
 	if ((sec > 59) || (min > 59))
-		cifs_dbg(VFS, "illegal time min %d sec %d\n", min, sec);
+		cifs_dbg(VFS, "illegal time min %d sec %lld\n", min, sec);
 	sec += (min * 60);
 	sec += 60 * 60 * st->Hours;
 	if (st->Hours > 24)
-- 
1.9.1