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 --- include/net/sctp/sctp.h | 2 +- include/net/sock.h | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) (limited to 'include/net') diff --git a/include/net/sctp/sctp.h b/include/net/sctp/sctp.h index a3353f45ef94..8e4de46c052e 100644 --- a/include/net/sctp/sctp.h +++ b/include/net/sctp/sctp.h @@ -101,7 +101,7 @@ void sctp_addr_wq_mgmt(struct net *, struct sctp_sockaddr_entry *, int); int sctp_backlog_rcv(struct sock *sk, struct sk_buff *skb); int sctp_inet_listen(struct socket *sock, int backlog); void sctp_write_space(struct sock *sk); -void sctp_data_ready(struct sock *sk, int len); +void sctp_data_ready(struct sock *sk); unsigned int sctp_poll(struct file *file, struct socket *sock, poll_table *wait); void sctp_sock_rfree(struct sk_buff *skb); diff --git a/include/net/sock.h b/include/net/sock.h index 06a5668f05c9..8338a14e4805 100644 --- a/include/net/sock.h +++ b/include/net/sock.h @@ -418,7 +418,7 @@ struct sock { u32 sk_classid; struct cg_proto *sk_cgrp; void (*sk_state_change)(struct sock *sk); - void (*sk_data_ready)(struct sock *sk, int bytes); + void (*sk_data_ready)(struct sock *sk); void (*sk_write_space)(struct sock *sk); void (*sk_error_report)(struct sock *sk); int (*sk_backlog_rcv)(struct sock *sk, -- cgit v1.2.3