From 676d23690fb62b5d51ba5d659935e9f7d9da9f8e Mon Sep 17 00:00:00 2001 From: "David S. Miller" Date: Fri, 11 Apr 2014 16:15:36 -0400 Subject: net: Fix use after free by removing length arg from sk_data_ready callbacks. Several spots in the kernel perform a sequence like: skb_queue_tail(&sk->s_receive_queue, skb); sk->sk_data_ready(sk, skb->len); But at the moment we place the SKB onto the socket receive queue it can be consumed and freed up. So this skb->len access is potentially to freed up memory. Furthermore, the skb->len can be modified by the consumer so it is possible that the value isn't accurate. And finally, no actual implementation of this callback actually uses the length argument. And since nobody actually cared about it's value, lots of call sites pass arbitrary values in such as '0' and even '1'. So just remove the length argument from the callback, that way there is no confusion whatsoever and all of these use-after-free cases get fixed as a side effect. Based upon a patch by Eric Dumazet and his suggestion to audit this issue tree-wide. Signed-off-by: David S. Miller --- net/dccp/input.c | 2 +- net/dccp/minisocks.c | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) (limited to 'net/dccp') diff --git a/net/dccp/input.c b/net/dccp/input.c index 14cdafad7a90..3c8ec7d4a34e 100644 --- a/net/dccp/input.c +++ b/net/dccp/input.c @@ -28,7 +28,7 @@ static void dccp_enqueue_skb(struct sock *sk, struct sk_buff *skb) __skb_pull(skb, dccp_hdr(skb)->dccph_doff * 4); __skb_queue_tail(&sk->sk_receive_queue, skb); skb_set_owner_r(skb, sk); - sk->sk_data_ready(sk, 0); + sk->sk_data_ready(sk); } static void dccp_fin(struct sock *sk, struct sk_buff *skb) diff --git a/net/dccp/minisocks.c b/net/dccp/minisocks.c index 9e2f78bc1553..c69eb9c4fbb8 100644 --- a/net/dccp/minisocks.c +++ b/net/dccp/minisocks.c @@ -237,7 +237,7 @@ int dccp_child_process(struct sock *parent, struct sock *child, /* Wakeup parent, send SIGIO */ if (state == DCCP_RESPOND && child->sk_state != state) - parent->sk_data_ready(parent, 0); + parent->sk_data_ready(parent); } else { /* Alas, it is possible again, because we do lookup * in main socket hash table and lock on listening -- cgit v1.2.3