linux-kernel - [PATCH 3.2 51/59] cifs: small underflow in cnvrtDosUnixTm()

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Date:   Fri, 18 Aug 2017 14:13:13 +0100
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, "Steve French" <smfrench@...il.com>,
        "Dan Carpenter" <dan.carpenter@...cle.com>
Subject: [PATCH 3.2 51/59] cifs: small underflow in cnvrtDosUnixTm()

3.2.92-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Dan Carpenter <dan.carpenter@...cle.com>

commit 564277eceeca01e02b1ef3e141cfb939184601b4 upstream.

January is month 1.  There is no zero-th month.  If someone passes a
zero month then it means we read from one space before the start of the
total_days_of_prev_months[] array.

We may as well also be strict about days as well.

Fixes: 1bd5bbcb6531 ("[CIFS] Legacy time handling for Win9x and OS/2 part 1")
Signed-off-by: Dan Carpenter <dan.carpenter@...cle.com>
Signed-off-by: Steve French <smfrench@...il.com>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 fs/cifs/netmisc.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

--- a/fs/cifs/netmisc.c
+++ b/fs/cifs/netmisc.c
@@ -974,10 +974,10 @@ struct timespec cnvrtDosUnixTm(__le16 le
 		cERROR(1, "illegal hours %d", st->Hours);
 	days = sd->Day;
 	month = sd->Month;
-	if ((days > 31) || (month > 12)) {
+	if (days < 1 || days > 31 || month < 1 || month > 12) {
 		cERROR(1, "illegal date, month %d day: %d", month, days);
-		if (month > 12)
-			month = 12;
+		days = clamp(days, 1, 31);
+		month = clamp(month, 1, 12);
 	}
 	month -= 1;
 	days += total_days_of_prev_months[month];