From: Paolo Abeni pabeni@redhat.com
commit 9adc89af724f12a03b47099cd943ed54e877cd59 upstream.
Currently the mentioned helper can end-up freeing the socket wmem without waking-up any processes waiting for more write memory.
If the partially orphaned skb is attached to an UDP (or raw) socket, the lack of wake-up can hang the user-space.
Even for TCP sockets not calling the sk destructor could have bad effects on TSQ.
Address the issue using skb_orphan to release the sk wmem before setting the new sock_efree destructor. Additionally bundle the whole ownership update in a new helper, so that later other potential users could avoid duplicate code.
v1 -> v2: - use skb_orphan() instead of sort of open coding it (Eric) - provide an helper for the ownership change (Eric)
Fixes: f6ba8d33cfbb ("netem: fix skb_orphan_partial()") Suggested-by: Eric Dumazet edumazet@google.com Signed-off-by: Paolo Abeni pabeni@redhat.com Reviewed-by: Eric Dumazet edumazet@google.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- include/net/sock.h | 9 +++++++++ net/core/sock.c | 12 +++--------- 2 files changed, 12 insertions(+), 9 deletions(-)
--- a/include/net/sock.h +++ b/include/net/sock.h @@ -2197,6 +2197,15 @@ static inline void skb_set_owner_r(struc sk_mem_charge(sk, skb->truesize); }
+static inline void skb_set_owner_sk_safe(struct sk_buff *skb, struct sock *sk) +{ + if (sk && refcount_inc_not_zero(&sk->sk_refcnt)) { + skb_orphan(skb); + skb->destructor = sock_efree; + skb->sk = sk; + } +} + void sk_reset_timer(struct sock *sk, struct timer_list *timer, unsigned long expires);
--- a/net/core/sock.c +++ b/net/core/sock.c @@ -2099,16 +2099,10 @@ void skb_orphan_partial(struct sk_buff * if (skb_is_tcp_pure_ack(skb)) return;
- if (can_skb_orphan_partial(skb)) { - struct sock *sk = skb->sk; - - if (refcount_inc_not_zero(&sk->sk_refcnt)) { - WARN_ON(refcount_sub_and_test(skb->truesize, &sk->sk_wmem_alloc)); - skb->destructor = sock_efree; - } - } else { + if (can_skb_orphan_partial(skb)) + skb_set_owner_sk_safe(skb, skb->sk); + else skb_orphan(skb); - } } EXPORT_SYMBOL(skb_orphan_partial);