ctcm: avoid wraparound in length of incoming data
Since the receive code should tolerate any incoming garbage, it
should be protected against a potential wraparound when manipulating
length values within incoming data.
block_len is unsigned, so a too large subtraction will cause a
wraparound.
Signed-off-by: Roel Kluin <roel.kluin@gmail.com>
Signed-off-by: Ursula Braun <ursula.braun@de.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/s390/net/ctcm_fsms.c b/drivers/s390/net/ctcm_fsms.c
index f29c708..4ded9ac 100644
--- a/drivers/s390/net/ctcm_fsms.c
+++ b/drivers/s390/net/ctcm_fsms.c
@@ -410,9 +410,8 @@
priv->stats.rx_length_errors++;
goto again;
}
- block_len -= 2;
- if (block_len > 0) {
- *((__u16 *)skb->data) = block_len;
+ if (block_len > 2) {
+ *((__u16 *)skb->data) = block_len - 2;
ctcm_unpack_skb(ch, skb);
}
again: