From 6c6baea5a8e9de8e542b98027d32e93abe744f36 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Sat, 30 May 2015 09:16:53 -0700 Subject: udp: fix behavior of wrong checksums 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. Change-Id: I9355321ac7ee564d56c342fa7738b918052bf308 Signed-off-by: Eric Dumazet Cc: Willem de Bruijn Signed-off-by: David S. Miller --- net/ipv4/udp.c | 6 ++---- net/ipv6/udp.c | 6 ++---- 2 files changed, 4 insertions(+), 8 deletions(-) (limited to 'net') diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c index 966c3e1..24c7f52 100644 --- a/net/ipv4/udp.c +++ b/net/ipv4/udp.c @@ -1249,10 +1249,8 @@ 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 5c363cd..62a3701 100644 --- a/net/ipv6/udp.c +++ b/net/ipv6/udp.c @@ -453,10 +453,8 @@ 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; } -- cgit v1.1