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| author | Willem de Bruijn <willemb@google.com> | 2017-04-12 19:24:35 -0400 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2017-04-17 12:59:22 -0400 |
| commit | 1862d6208db0aeca9c8ace44915b08d5ab2cd667 (patch) | |
| tree | c0cdc74a6b4246fd90bf4163a5c263f92735ccab /net/core | |
| parent | 1215e51edad1272e669172b26aa12aac94810c7f (diff) | |
| download | linux-1862d6208db0aeca9c8ace44915b08d5ab2cd667.tar.bz2 | |
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/core')
| -rw-r--r-- | net/core/skbuff.c | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/net/core/skbuff.c b/net/core/skbuff.c index 9f781092fda9..35c1e2460206 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -3807,6 +3807,7 @@ static void __skb_complete_tx_timestamp(struct sk_buff *skb, serr->ee.ee_origin = SO_EE_ORIGIN_TIMESTAMPING; serr->ee.ee_info = tstype; serr->opt_stats = opt_stats; + serr->header.h4.iif = skb->dev ? skb->dev->ifindex : 0; if (sk->sk_tsflags & SOF_TIMESTAMPING_OPT_ID) { serr->ee.ee_data = skb_shinfo(skb)->tskey; if (sk->sk_protocol == IPPROTO_TCP && |