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authorEric Dumazet <edumazet@google.com>2018-01-18 19:59:19 -0800
committerDavid S. Miller <davem@davemloft.net>2018-01-22 16:00:05 -0500
commit7c68d1a6b4db9012790af7ac0f0fdc0d2083422a (patch)
tree080fa20981e54ee032dc59e2e80a925f9d7c4dd7 /net/core
parent18b0affaf40cf5f320258d28f7069dfff76da184 (diff)
net: qdisc_pkt_len_init() should be more robust
Without proper validation of DODGY packets, we might very well feed qdisc_pkt_len_init() with invalid GSO packets. tcp_hdrlen() might access out-of-bound data, so let's use skb_header_pointer() and proper checks. Whole story is described in commit d0c081b49137 ("flow_dissector: properly cap thoff field") We have the goal of validating DODGY packets earlier in the stack, so we might very well revert this fix in the future. Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Willem de Bruijn <willemb@google.com> Cc: Jason Wang <jasowang@redhat.com> Reported-by: syzbot+9da69ebac7dddd804552@syzkaller.appspotmail.com Acked-by: Jason Wang <jasowang@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/core')
-rw-r--r--net/core/dev.c19
1 files changed, 15 insertions, 4 deletions
diff --git a/net/core/dev.c b/net/core/dev.c
index 0e0ba36eeac9..613fb4066be7 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -3151,10 +3151,21 @@ static void qdisc_pkt_len_init(struct sk_buff *skb)
hdr_len = skb_transport_header(skb) - skb_mac_header(skb);
/* + transport layer */
- if (likely(shinfo->gso_type & (SKB_GSO_TCPV4 | SKB_GSO_TCPV6)))
- hdr_len += tcp_hdrlen(skb);
- else
- hdr_len += sizeof(struct udphdr);
+ if (likely(shinfo->gso_type & (SKB_GSO_TCPV4 | SKB_GSO_TCPV6))) {
+ const struct tcphdr *th;
+ struct tcphdr _tcphdr;
+
+ th = skb_header_pointer(skb, skb_transport_offset(skb),
+ sizeof(_tcphdr), &_tcphdr);
+ if (likely(th))
+ hdr_len += __tcp_hdrlen(th);
+ } else {
+ struct udphdr _udphdr;
+
+ if (skb_header_pointer(skb, skb_transport_offset(skb),
+ sizeof(_udphdr), &_udphdr))
+ hdr_len += sizeof(struct udphdr);
+ }
if (shinfo->gso_type & SKB_GSO_DODGY)
gso_segs = DIV_ROUND_UP(skb->len - hdr_len,