From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dan Carpenter Subject: [PATCH v2] cifs: small underflow in cnvrtDosUnixTm() Date: Fri, 28 Apr 2017 15:51:30 +0300 Message-ID: <20170428125130.4y22bpllksfyb37k@mwanda> References: <20170410134931.GC1918@mwanda> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: linux-cifs-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, samba-technical-w/Ol4Ecudpl8XjKLYN78aQ@public.gmane.org, kernel-janitors-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Steve French Return-path: Content-Disposition: inline In-Reply-To: <20170410134931.GC1918@mwanda> Sender: linux-cifs-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-ID: 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 --- v2: Be strict about days as well. My first patch was less intrusive because it only prevented the out of bounds access. I have no idea how common it is to pass in an illegal day but, hopefully, not very common. diff --git a/fs/cifs/netmisc.c b/fs/cifs/netmisc.c index abae6dd2c6b9..4b2726ee4fad 100644 --- a/fs/cifs/netmisc.c +++ b/fs/cifs/netmisc.c @@ -980,10 +980,10 @@ struct timespec cnvrtDosUnixTm(__le16 le_date, __le16 le_time, int offset) cifs_dbg(VFS, "illegal hours %d\n", st->Hours); days = sd->Day; month = sd->Month; - if ((days > 31) || (month > 12)) { + if (days < 1 || days > 31 || month < 1 || month > 12) { cifs_dbg(VFS, "illegal date, month %d day: %d\n", month, days); - if (month > 12) - month = 12; + days = (days < 1) ? 1 : ((days <= 31) ? days : 31); + month = (month < 1) ? 1 : ((month <= 12) ? month : 12); } month -= 1; days += total_days_of_prev_months[month];