From e962d472ed829d1be4a708a8701ce8bab163fb8d Mon Sep 17 00:00:00 2001 From: Or Cohen Date: Tue, 22 Sep 2020 10:23:54 +0800 Subject: [PATCH] net/packet: fix overflow in tpacket_rcv mainline inclusion from mainline-v5.9-rc4 commit acf69c946233259ab4d64f8869d4037a198c7f06 category: bugfix bugzilla: NA CVE: CVE-2020-14386 -------------------------------- Using tp_reserve to calculate netoff can overflow as tp_reserve is unsigned int and netoff is unsigned short. This may lead to macoff receving a smaller value then sizeof(struct virtio_net_hdr), and if po->has_vnet_hdr is set, an out-of-bounds write will occur when calling virtio_net_hdr_from_skb. The bug is fixed by converting netoff to unsigned int and checking if it exceeds USHRT_MAX. This addresses CVE-2020-14386 Fixes: 8913336a7e8d ("packet: add PACKET_RESERVE sockopt") Signed-off-by: Or Cohen Signed-off-by: Eric Dumazet Signed-off-by: Linus Torvalds Signed-off-by: Yang Yingliang Reviewed-by: Yue Haibing Reviewed-by: Jason Yan Signed-off-by: Yang Yingliang --- net/packet/af_packet.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c index 539dd755685c..4c2f431e367b 100644 --- a/net/packet/af_packet.c +++ b/net/packet/af_packet.c @@ -2158,7 +2158,8 @@ static int tpacket_rcv(struct sk_buff *skb, struct net_device *dev, int skb_len = skb->len; unsigned int snaplen, res; unsigned long status = TP_STATUS_USER; - unsigned short macoff, netoff, hdrlen; + unsigned short macoff, hdrlen; + unsigned int netoff; struct sk_buff *copy_skb = NULL; struct timespec ts; __u32 ts_status; @@ -2221,6 +2222,10 @@ static int tpacket_rcv(struct sk_buff *skb, struct net_device *dev, } macoff = netoff - maclen; } + if (netoff > USHRT_MAX) { + atomic_inc(&po->tp_drops); + goto drop_n_restore; + } if (po->tp_version <= TPACKET_V2) { if (macoff + snaplen > po->rx_ring.frame_size) { if (po->copy_thresh && -- GitLab