diff options
| author | Willem de Bruijn <willemb@google.com> | 2017-04-13 02:24:35 +0300 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2017-04-17 19:59:22 +0300 |
| commit | 1862d6208db0aeca9c8ace44915b08d5ab2cd667 (patch) | |
| tree | c0cdc74a6b4246fd90bf4163a5c263f92735ccab /net/ipv4 | |
| parent | 1215e51edad1272e669172b26aa12aac94810c7f (diff) | |
| download | linux-1862d6208db0aeca9c8ace44915b08d5ab2cd667.tar.xz | |
net-timestamp: avoid use-after-free in ip_recv_error
Syzkaller reported a use-after-free in ip_recv_error at line
info->ipi_ifindex = skb->dev->ifindex;
This function is called on dequeue from the error queue, at which
point the device pointer may no longer be valid.
Save ifindex on enqueue in __skb_complete_tx_timestamp, when the
pointer is valid or NULL. Store it in temporary storage skb->cb.
It is safe to reference skb->dev here, as called from device drivers
or dev_queue_xmit. The exception is when called from tcp_ack_tstamp;
in that case it is NULL and ifindex is set to 0 (invalid).
Do not return a pktinfo cmsg if ifindex is 0. This maintains the
current behavior of not returning a cmsg if skb->dev was NULL.
On dequeue, the ipv4 path will cast from sock_exterr_skb to
in_pktinfo. Both have ifindex as their first element, so no explicit
conversion is needed. This is by design, introduced in commit
0b922b7a829c ("net: original ingress device index in PKTINFO"). For
ipv6 ip6_datagram_support_cmsg converts to in6_pktinfo.
Fixes: 829ae9d61165 ("net-timestamp: allow reading recv cmsg on errqueue with origin tstamp")
Reported-by: Andrey Konovalov <andreyknvl@google.com>
Signed-off-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4')
| -rw-r--r-- | net/ipv4/ip_sockglue.c | 9 |
1 files changed, 4 insertions, 5 deletions
diff --git a/net/ipv4/ip_sockglue.c b/net/ipv4/ip_sockglue.c index bda318ae9876..1d46d05efb0f 100644 --- a/net/ipv4/ip_sockglue.c +++ b/net/ipv4/ip_sockglue.c @@ -488,16 +488,15 @@ static bool ipv4_datagram_support_cmsg(const struct sock *sk, return false; /* Support IP_PKTINFO on tstamp packets if requested, to correlate - * timestamp with egress dev. Not possible for packets without dev + * timestamp with egress dev. Not possible for packets without iif * or without payload (SOF_TIMESTAMPING_OPT_TSONLY). */ - if ((!(sk->sk_tsflags & SOF_TIMESTAMPING_OPT_CMSG)) || - (!skb->dev)) + info = PKTINFO_SKB_CB(skb); + if (!(sk->sk_tsflags & SOF_TIMESTAMPING_OPT_CMSG) || + !info->ipi_ifindex) return false; - info = PKTINFO_SKB_CB(skb); info->ipi_spec_dst.s_addr = ip_hdr(skb)->saddr; - info->ipi_ifindex = skb->dev->ifindex; return true; } |