netdev - [PATCH net] 6lowpan: Off by one handling ->nexthdr

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Date:   Wed, 3 Apr 2019 08:34:16 +0300
From:   Dan Carpenter <dan.carpenter@...cle.com>
To:     Alexander Aring <alex.aring@...il.com>
Cc:     Jukka Rissanen <jukka.rissanen@...ux.intel.com>,
        "David S. Miller" <davem@...emloft.net>,
        linux-bluetooth@...r.kernel.org, linux-wpan@...r.kernel.org,
        netdev@...r.kernel.org, kernel-janitors@...r.kernel.org
Subject: [PATCH net] 6lowpan: Off by one handling ->nexthdr

NEXTHDR_MAX is 255.  What happens here is that we take a u8 value
"hdr->nexthdr" from the network and then look it up in
lowpan_nexthdr_nhcs[].  The problem is that if hdr->nexthdr is 0xff then
we read one element beyond the end of the array so the array needs to
be one element larger.

Fixes: 92aa7c65d295 ("6lowpan: add generic nhc layer interface")
Signed-off-by: Dan Carpenter <dan.carpenter@...cle.com>
---
This is the only place which uses the NEXTHDR_MAX define, so I considered
changing that to 256 instead.  Either fix would work.

 net/6lowpan/nhc.c  | 2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/net/6lowpan/nhc.c b/net/6lowpan/nhc.c
index 4fa2fdda174d..9e56fb98f33c 100644
--- a/net/6lowpan/nhc.c
+++ b/net/6lowpan/nhc.c
@@ -18,7 +18,7 @@
 #include "nhc.h"
 
 static struct rb_root rb_root = RB_ROOT;
-static struct lowpan_nhc *lowpan_nexthdr_nhcs[NEXTHDR_MAX];
+static struct lowpan_nhc *lowpan_nexthdr_nhcs[NEXTHDR_MAX + 1];
 static DEFINE_SPINLOCK(lowpan_nhc_lock);
 
 static int lowpan_nhc_insert(struct lowpan_nhc *nhc)
-- 
2.17.1