[PATCH AUTOSEL 4.9 120/251] 6lowpan: Off by one handling ->nexthdr

Sasha Levin
2020-01-16T17:39:24Z

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

[ Upstream commit f57c4bbf34439531adccd7d3a4ecc14f409c1399 ]

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@oracle.com>
Acked-by: Jukka Rissanen <jukka.rissanen@linux.intel.com>
Acked-by: Alexander Aring <aring@mojatatu.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
net/6lowpan/nhc.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/6lowpan/nhc.c b/net/6lowpan/nhc.c
index 7008d53e455c..e61679bf0908 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)
--
2.20.1