From 537cf4e3cc2f6cc9088dcd6162de573f603adc29 Mon Sep 17 00:00:00 2001 From: Magnus Karlsson Date: Fri, 20 Nov 2020 12:53:39 +0100 Subject: xsk: Fix umem cleanup bug at socket destruct Fix a bug that is triggered when a partially setup socket is destroyed. For a fully setup socket, a socket that has been bound to a device, the cleanup of the umem is performed at the end of the buffer pool's cleanup work queue item. This has to be performed in a work queue, and not in RCU cleanup, as it is doing a vunmap that cannot execute in interrupt context. However, when a socket has only been partially set up so that a umem has been created but the buffer pool has not, the code erroneously directly calls the umem cleanup function instead of using a work queue, and this leads to a BUG_ON() in vunmap(). As there in this case is no buffer pool, we cannot use its work queue, so we need to introduce a work queue for the umem and schedule this for the cleanup. So in the case there is no pool, we are going to use the umem's own work queue to schedule the cleanup. But if there is a pool, the cleanup of the umem is still being performed by the pool's work queue, as it is important that the umem is cleaned up after the pool. Fixes: e5e1a4bc916d ("xsk: Fix possible memory leak at socket close") Reported-by: Marek Majtyka Signed-off-by: Magnus Karlsson Signed-off-by: Daniel Borkmann Tested-by: Marek Majtyka Link: https://lore.kernel.org/bpf/1605873219-21629-1-git-send-email-magnus.karlsson@gmail.com --- include/net/xdp_sock.h | 1 + 1 file changed, 1 insertion(+) (limited to 'include') diff --git a/include/net/xdp_sock.h b/include/net/xdp_sock.h index 1a9559c0cbdd..4f4e93bf814c 100644 --- a/include/net/xdp_sock.h +++ b/include/net/xdp_sock.h @@ -31,6 +31,7 @@ struct xdp_umem { struct page **pgs; int id; struct list_head xsk_dma_list; + struct work_struct work; }; struct xsk_map { -- cgit v1.2.3 From 36ccdf85829a7dd6936dba5d02fa50138471f0d3 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Bj=C3=B6rn=20T=C3=B6pel?= Date: Mon, 23 Nov 2020 18:56:00 +0100 Subject: net, xsk: Avoid taking multiple skbuff references MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Commit 642e450b6b59 ("xsk: Do not discard packet when NETDEV_TX_BUSY") addressed the problem that packets were discarded from the Tx AF_XDP ring, when the driver returned NETDEV_TX_BUSY. Part of the fix was bumping the skbuff reference count, so that the buffer would not be freed by dev_direct_xmit(). A reference count larger than one means that the skbuff is "shared", which is not the case. If the "shared" skbuff is sent to the generic XDP receive path, netif_receive_generic_xdp(), and pskb_expand_head() is entered the BUG_ON(skb_shared(skb)) will trigger. This patch adds a variant to dev_direct_xmit(), __dev_direct_xmit(), where a user can select the skbuff free policy. This allows AF_XDP to avoid bumping the reference count, but still keep the NETDEV_TX_BUSY behavior. Fixes: 642e450b6b59 ("xsk: Do not discard packet when NETDEV_TX_BUSY") Reported-by: Yonghong Song Signed-off-by: Björn Töpel Signed-off-by: Daniel Borkmann Link: https://lore.kernel.org/bpf/20201123175600.146255-1-bjorn.topel@gmail.com --- include/linux/netdevice.h | 14 +++++++++++++- 1 file changed, 13 insertions(+), 1 deletion(-) (limited to 'include') diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h index 964b494b0e8d..76775abf259d 100644 --- a/include/linux/netdevice.h +++ b/include/linux/netdevice.h @@ -2813,9 +2813,21 @@ u16 dev_pick_tx_zero(struct net_device *dev, struct sk_buff *skb, struct net_device *sb_dev); u16 dev_pick_tx_cpu_id(struct net_device *dev, struct sk_buff *skb, struct net_device *sb_dev); + int dev_queue_xmit(struct sk_buff *skb); int dev_queue_xmit_accel(struct sk_buff *skb, struct net_device *sb_dev); -int dev_direct_xmit(struct sk_buff *skb, u16 queue_id); +int __dev_direct_xmit(struct sk_buff *skb, u16 queue_id); + +static inline int dev_direct_xmit(struct sk_buff *skb, u16 queue_id) +{ + int ret; + + ret = __dev_direct_xmit(skb, queue_id); + if (!dev_xmit_complete(ret)) + kfree_skb(skb); + return ret; +} + int register_netdevice(struct net_device *dev); void unregister_netdevice_queue(struct net_device *dev, struct list_head *head); void unregister_netdevice_many(struct list_head *head); -- cgit v1.2.3