linux-kernel - [PATCH] smbfs: Read buffer overflow

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Date:	Thu, 23 Jul 2009 17:48:49 +0200
From:	Roel Kluin <roel.kluin@...il.com>
To:	LKML <linux-kernel@...r.kernel.org>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: [PATCH] smbfs: Read buffer overflow

This function uses signed integers for the unix_date and local variables - if a
negative number is supplied and the leap-year condition is not met, month
will be 0, leading to a read of day_n[-1]

Signed-off-by: Roel Kluin <roel.kluin@...il.com>
---
This is the easiest way to prevent the buffer overflow, but it produces a date.
Maybe a magic date would be better? What should we choose?

Credits to Parfait and Nathan Keynes,

diff --git a/fs/smbfs/proc.c b/fs/smbfs/proc.c
index 9468168..71c29b6 100644
--- a/fs/smbfs/proc.c
+++ b/fs/smbfs/proc.c
@@ -509,7 +509,7 @@ date_unix2dos(struct smb_sb_info *server,
 		month = 2;
 	} else {
 		nl_day = (year & 3) || day <= 59 ? day : day - 1;
-		for (month = 0; month < 12; month++)
+		for (month = 1; month < 12; month++)
 			if (day_n[month] > nl_day)
 				break;
 	}
--
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