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authorEric Dumazet <edumazet@google.com>2015-05-30 09:16:53 -0700
committerZefan Li <lizefan@huawei.com>2015-09-18 09:20:47 +0800
commit1c50a0ae29d0224bd75ff1ace8819ae1f266bf8a (patch)
treefd9d72e85257a95bb4c6248586aa3b960e8cdd67
parentaaedb09057b05c7c9e213dc465bff5f70e708535 (diff)
udp: fix behavior of wrong checksums
commit beb39db59d14990e401e235faf66a6b9b31240b0 upstream. We have two problems in UDP stack related to bogus checksums : 1) We return -EAGAIN to application even if receive queue is not empty. This breaks applications using edge trigger epoll() 2) Under UDP flood, we can loop forever without yielding to other processes, potentially hanging the host, especially on non SMP. This patch is an attempt to make things better. We might in the future add extra support for rt applications wanting to better control time spent doing a recv() in a hostile environment. For example we could validate checksums before queuing packets in socket receive queue. Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Willem de Bruijn <willemb@google.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Zefan Li <lizefan@huawei.com>
-rw-r--r--net/ipv4/udp.c6
-rw-r--r--net/ipv6/udp.c6
2 files changed, 4 insertions, 8 deletions
diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index 7949b5d1663f..5f8c20b67da2 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -1251,10 +1251,8 @@ csum_copy_err:
UDP_INC_STATS_USER(sock_net(sk), UDP_MIB_INERRORS, is_udplite);
unlock_sock_fast(sk, slow);
- if (noblock)
- return -EAGAIN;
-
- /* starting over for a new packet */
+ /* starting over for a new packet, but check if we need to yield */
+ cond_resched();
msg->msg_flags &= ~MSG_TRUNC;
goto try_again;
}
diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
index ef9052f8c90b..2f99b12b717e 100644
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c
@@ -451,10 +451,8 @@ csum_copy_err:
}
unlock_sock_fast(sk, slow);
- if (noblock)
- return -EAGAIN;
-
- /* starting over for a new packet */
+ /* starting over for a new packet, but check if we need to yield */
+ cond_resched();
msg->msg_flags &= ~MSG_TRUNC;
goto try_again;
}