Commit c7c49b8f authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

net: add pfmemalloc check in sk_add_backlog()

Greg reported crashes hitting the following check in __sk_backlog_rcv()

	BUG_ON(!sock_flag(sk, SOCK_MEMALLOC));

The pfmemalloc bit is currently checked in sk_filter().

This works correctly for TCP, because sk_filter() is ran in
tcp_v[46]_rcv() before hitting the prequeue or backlog checks.

For UDP or other protocols, this does not work, because the sk_filter()
is ran from sock_queue_rcv_skb(), which might be called _after_ backlog
queuing if socket is owned by user by the time packet is processed by
softirq handler.

Fixes: b4b9e355

 ("netvm: set PF_MEMALLOC as appropriate during SKB processing")
Signed-off-by: default avatarEric Dumazet <>
Reported-by: default avatarGreg Thelen <>
Signed-off-by: default avatarDavid S. Miller <>
parent 5f715c09
......@@ -828,6 +828,14 @@ static inline __must_check int sk_add_backlog(struct sock *sk, struct sk_buff *s
if (sk_rcvqueues_full(sk, limit))
return -ENOBUFS;
* If the skb was allocated from pfmemalloc reserves, only
* allow SOCK_MEMALLOC sockets to use it as this socket is
* helping free memory
if (skb_pfmemalloc(skb) && !sock_flag(sk, SOCK_MEMALLOC))
return -ENOMEM;
__sk_add_backlog(sk, skb);
sk->sk_backlog.len += skb->truesize;
return 0;
Supports Markdown
0% or .
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment