diff options
| author | Willem de Bruijn <willemb@google.com> | 2019-01-07 16:47:33 -0500 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2019-01-10 09:27:20 -0500 |
| commit | 4a06fa67c4da20148803525151845276cdb995c1 (patch) | |
| tree | fce2609c8420b949997d123cec8aacd178a0cd1d /net/ipv6 | |
| parent | 0b7959b6257322f7693b08a459c505d4938646f2 (diff) | |
ip: on queued skb use skb_header_pointer instead of pskb_may_pull
Commit 2efd4fca703a ("ip: in cmsg IP(V6)_ORIGDSTADDR call
pskb_may_pull") avoided a read beyond the end of the skb linear
segment by calling pskb_may_pull.
That function can trigger a BUG_ON in pskb_expand_head if the skb is
shared, which it is when when peeking. It can also return ENOMEM.
Avoid both by switching to safer skb_header_pointer.
Fixes: 2efd4fca703a ("ip: in cmsg IP(V6)_ORIGDSTADDR call pskb_may_pull")
Reported-by: syzbot <syzkaller@googlegroups.com>
Suggested-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv6')
| -rw-r--r-- | net/ipv6/datagram.c | 10 |
1 files changed, 4 insertions, 6 deletions
diff --git a/net/ipv6/datagram.c b/net/ipv6/datagram.c index bde08aa549f3..c2262a7e2088 100644 --- a/net/ipv6/datagram.c +++ b/net/ipv6/datagram.c @@ -700,17 +700,15 @@ void ip6_datagram_recv_specific_ctl(struct sock *sk, struct msghdr *msg, } if (np->rxopt.bits.rxorigdstaddr) { struct sockaddr_in6 sin6; - __be16 *ports; - int end; + __be16 _ports[2], *ports; - end = skb_transport_offset(skb) + 4; - if (end <= 0 || pskb_may_pull(skb, end)) { + ports = skb_header_pointer(skb, skb_transport_offset(skb), + sizeof(_ports), &_ports); + if (ports) { /* All current transport protocols have the port numbers in the * first four bytes of the transport header and this function is * written with this assumption in mind. */ - ports = (__be16 *)skb_transport_header(skb); - sin6.sin6_family = AF_INET6; sin6.sin6_addr = ipv6_hdr(skb)->daddr; sin6.sin6_port = ports[1]; |