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| author | Eric Dumazet <edumazet@google.com> | 2015-09-29 18:52:25 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2015-10-27 09:53:36 +0900 |
| commit | 3f56dd94c0e03df9ad8ddb1c7c97bbf6287cd6ea (patch) | |
| tree | 7dd17fa27b16562c5bd2bc4303e640db1cbf229a | |
| parent | c4e11ec108c09333ae16565515bd2e2349369d2a (diff) | |
| download | lwn-3f56dd94c0e03df9ad8ddb1c7c97bbf6287cd6ea.tar.gz lwn-3f56dd94c0e03df9ad8ddb1c7c97bbf6287cd6ea.zip | |
net: add pfmemalloc check in sk_add_backlog()
[ Upstream commit c7c49b8fde26b74277188bdc6c9dca38db6fa35b ]
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: b4b9e35585089 ("netvm: set PF_MEMALLOC as appropriate during SKB processing")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Greg Thelen <gthelen@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | include/net/sock.h | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/include/net/sock.h b/include/net/sock.h index f21f0708ec59..4ca4c3fe446f 100644 --- a/include/net/sock.h +++ b/include/net/sock.h @@ -826,6 +826,14 @@ 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; |