From 5d4c9bfbabdb1d497f21afd81501e5c54b0c85d9 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Wed, 18 Nov 2015 21:03:33 -0800 Subject: [PATCH] tcp: fix potential huge kmalloc() calls in TCP_REPAIR tcp_send_rcvq() is used for re-injecting data into tcp receive queue. Problems : - No check against size is performed, allowed user to fool kernel in attempting very large memory allocations, eventually triggering OOM when memory is fragmented. - In case of fault during the copy we do not return correct errno. Lets use alloc_skb_with_frags() to cook optimal skbs. Fixes: 292e8d8c8538 ("tcp: Move rcvq sending to tcp_input.c") Fixes: c0e88ff0f256 ("tcp: Repair socket queues") Signed-off-by: Eric Dumazet Cc: Pavel Emelyanov Acked-by: Pavel Emelyanov Signed-off-by: David S. Miller --- net/ipv4/tcp_input.c | 22 +++++++++++++++++++--- 1 file changed, 19 insertions(+), 3 deletions(-) diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index fdd88c3803a6..a4a0b6b3bcf2 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -4481,19 +4481,34 @@ static int __must_check tcp_queue_rcv(struct sock *sk, struct sk_buff *skb, int int tcp_send_rcvq(struct sock *sk, struct msghdr *msg, size_t size) { struct sk_buff *skb; + int err = -ENOMEM; + int data_len = 0; bool fragstolen; if (size == 0) return 0; - skb = alloc_skb(size, sk->sk_allocation); + if (size > PAGE_SIZE) { + int npages = min_t(size_t, size >> PAGE_SHIFT, MAX_SKB_FRAGS); + + data_len = npages << PAGE_SHIFT; + size = data_len + (size & ~PAGE_MASK); + } + skb = alloc_skb_with_frags(size - data_len, data_len, + PAGE_ALLOC_COSTLY_ORDER, + &err, sk->sk_allocation); if (!skb) goto err; + skb_put(skb, size - data_len); + skb->data_len = data_len; + skb->len = size; + if (tcp_try_rmem_schedule(sk, skb, skb->truesize)) goto err_free; - if (memcpy_from_msg(skb_put(skb, size), msg, size)) + err = skb_copy_datagram_from_iter(skb, 0, &msg->msg_iter, size); + if (err) goto err_free; TCP_SKB_CB(skb)->seq = tcp_sk(sk)->rcv_nxt; @@ -4509,7 +4524,8 @@ int tcp_send_rcvq(struct sock *sk, struct msghdr *msg, size_t size) err_free: kfree_skb(skb); err: - return -ENOMEM; + return err; + } static void tcp_data_queue(struct sock *sk, struct sk_buff *skb) -- 2.20.1