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authorEric Dumazet <edumazet@google.com>2015-09-29 18:52:25 -0700
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2015-10-27 09:51:49 +0900
commitfac948a1c4188780633c4ef509941876dcc99502 (patch)
treeb9bc33c64470042fb89437b2ed38e7293add9334
parent31b8abd140ad0be5f63bae0e4e6beb9d52b16f85 (diff)
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.h8
1 files changed, 8 insertions, 0 deletions
diff --git a/include/net/sock.h b/include/net/sock.h
index 3a4898ec8c67..ed01a012f8d5 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;