From f44b3ed1bd2a6bd3d0178eab39b3ae016b8f51bc Mon Sep 17 00:00:00 2001 From: "subashab@codeaurora.org" Date: Fri, 23 Jan 2015 22:26:02 +0000 Subject: ping: Fix race in free in receive path [ Upstream commit fc752f1f43c1c038a2c6ae58cc739ebb5953ccb0 ] An exception is seen in ICMP ping receive path where the skb destructor sock_rfree() tries to access a freed socket. This happens because ping_rcv() releases socket reference with sock_put() and this internally frees up the socket. Later icmp_rcv() will try to free the skb and as part of this, skb destructor is called and which leads to a kernel panic as the socket is freed already in ping_rcv(). -->|exception -007|sk_mem_uncharge -007|sock_rfree -008|skb_release_head_state -009|skb_release_all -009|__kfree_skb -010|kfree_skb -011|icmp_rcv -012|ip_local_deliver_finish Fix this incorrect free by cloning this skb and processing this cloned skb instead. This patch was suggested by Eric Dumazet Signed-off-by: Subash Abhinov Kasiviswanathan Cc: Eric Dumazet Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/ipv4/ping.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) diff --git a/net/ipv4/ping.c b/net/ipv4/ping.c index d99c80b5a..0f49b1071 100644 --- a/net/ipv4/ping.c +++ b/net/ipv4/ping.c @@ -257,7 +257,7 @@ int ping_init_sock(struct sock *sk) int i, j, count; kgid_t low, high; int ret = 0; - + inet_get_ping_group_range_net(net, &low, &high); if (gid_lte(low, group) && gid_lte(group, high)) return 0; @@ -966,12 +966,18 @@ void ping_rcv(struct sk_buff *skb) sk = ping_lookup(net, skb, ntohs(icmph->un.echo.id)); if (sk != NULL) { -#ifdef CONFIG_MTK_NET_LOGGING +#ifdef CONFIG_MTK_NET_LOGGING printk(KERN_INFO "[mtk_net][ping_debug]rcv on sk %p\n", sk); #endif ping_queue_rcv_skb(sk, skb_get(skb)); /*mtk_net: don't put sock here, do sock_put after free skb*/ /* sock_put(sk); */ + struct sk_buff *skb2 = skb_clone(skb, GFP_ATOMIC); + + pr_debug("rcv on socket %p\n", sk); + if (skb2) + ping_queue_rcv_skb(sk, skb2); + sock_put(sk); return; } pr_info("[mtk_net][ping_debug]no socket, dropping\n"); -- cgit v1.2.3