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authorWillem de Bruijn <willemb@google.com>2017-04-12 19:24:35 -0400
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2017-05-03 08:36:36 -0700
commit8c04e2acd5371387f5e42e3bab412c291d108391 (patch)
tree7b1160bf38b1127633b85bd1fa72ea9fa1996f31 /net/core
parentc86872a43400c1e5df2acbd9bb23e3941ef1c98d (diff)
net-timestamp: avoid use-after-free in ip_recv_error
[ Upstream commit 1862d6208db0aeca9c8ace44915b08d5ab2cd667 ] 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> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'net/core')
-rw-r--r--net/core/skbuff.c1
1 files changed, 1 insertions, 0 deletions
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index f0f462c0573d..5ec34eae3f0a 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -3779,6 +3779,7 @@ static void __skb_complete_tx_timestamp(struct sk_buff *skb,
serr->ee.ee_errno = ENOMSG;
serr->ee.ee_origin = SO_EE_ORIGIN_TIMESTAMPING;
serr->ee.ee_info = tstype;
+ 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 &&