From 69629464e0b587f3711739b3aa2bcdaf2e075276 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Sun, 5 Feb 2017 09:25:24 -0800 Subject: [PATCH] udp: properly cope with csum errors Dmitry reported that UDP sockets being destroyed would trigger the WARN_ON(atomic_read(&sk->sk_rmem_alloc)); in inet_sock_destruct() It turns out we do not properly destroy skb(s) that have wrong UDP checksum. Thanks again to syzkaller team. Fixes : 7c13f97ffde6 ("udp: do fwd memory scheduling on dequeue") Reported-by: Dmitry Vyukov Signed-off-by: Eric Dumazet Cc: Paolo Abeni Cc: Hannes Frederic Sowa Acked-by: Paolo Abeni Signed-off-by: David S. Miller --- include/net/sock.h | 4 +++- net/core/datagram.c | 8 ++++++-- net/ipv4/udp.c | 2 +- net/ipv6/udp.c | 2 +- 4 files changed, 11 insertions(+), 5 deletions(-) diff --git a/include/net/sock.h b/include/net/sock.h index f0e867f58722..c4f5e6fca17c 100644 --- a/include/net/sock.h +++ b/include/net/sock.h @@ -2006,7 +2006,9 @@ void sk_reset_timer(struct sock *sk, struct timer_list *timer, void sk_stop_timer(struct sock *sk, struct timer_list *timer); int __sk_queue_drop_skb(struct sock *sk, struct sk_buff *skb, - unsigned int flags); + unsigned int flags, + void (*destructor)(struct sock *sk, + struct sk_buff *skb)); int __sock_queue_rcv_skb(struct sock *sk, struct sk_buff *skb); int sock_queue_rcv_skb(struct sock *sk, struct sk_buff *skb); diff --git a/net/core/datagram.c b/net/core/datagram.c index 662bea587165..ea633342ab0d 100644 --- a/net/core/datagram.c +++ b/net/core/datagram.c @@ -332,7 +332,9 @@ void __skb_free_datagram_locked(struct sock *sk, struct sk_buff *skb, int len) EXPORT_SYMBOL(__skb_free_datagram_locked); int __sk_queue_drop_skb(struct sock *sk, struct sk_buff *skb, - unsigned int flags) + unsigned int flags, + void (*destructor)(struct sock *sk, + struct sk_buff *skb)) { int err = 0; @@ -342,6 +344,8 @@ int __sk_queue_drop_skb(struct sock *sk, struct sk_buff *skb, if (skb == skb_peek(&sk->sk_receive_queue)) { __skb_unlink(skb, &sk->sk_receive_queue); atomic_dec(&skb->users); + if (destructor) + destructor(sk, skb); err = 0; } spin_unlock_bh(&sk->sk_receive_queue.lock); @@ -375,7 +379,7 @@ EXPORT_SYMBOL(__sk_queue_drop_skb); int skb_kill_datagram(struct sock *sk, struct sk_buff *skb, unsigned int flags) { - int err = __sk_queue_drop_skb(sk, skb, flags); + int err = __sk_queue_drop_skb(sk, skb, flags, NULL); kfree_skb(skb); sk_mem_reclaim_partial(sk); diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c index 1307a7c2e544..8aab7d78d25b 100644 --- a/net/ipv4/udp.c +++ b/net/ipv4/udp.c @@ -1501,7 +1501,7 @@ int udp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, int noblock, return err; csum_copy_err: - if (!__sk_queue_drop_skb(sk, skb, flags)) { + if (!__sk_queue_drop_skb(sk, skb, flags, udp_skb_destructor)) { UDP_INC_STATS(sock_net(sk), UDP_MIB_CSUMERRORS, is_udplite); UDP_INC_STATS(sock_net(sk), UDP_MIB_INERRORS, is_udplite); } diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c index 4d5c4eee4b3f..8990856f5101 100644 --- a/net/ipv6/udp.c +++ b/net/ipv6/udp.c @@ -441,7 +441,7 @@ int udpv6_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, return err; csum_copy_err: - if (!__sk_queue_drop_skb(sk, skb, flags)) { + if (!__sk_queue_drop_skb(sk, skb, flags, udp_skb_destructor)) { if (is_udp4) { UDP_INC_STATS(sock_net(sk), UDP_MIB_CSUMERRORS, is_udplite);