From 071d36bf21bcc837be00cea55bcef8d129e7f609 Mon Sep 17 00:00:00 2001 From: "subashab@codeaurora.org" Date: Wed, 23 Mar 2016 22:39:50 -0600 Subject: xfrm: Fix crash observed during device unregistration and decryption A crash is observed when a decrypted packet is processed in receive path. get_rps_cpus() tries to dereference the skb->dev fields but it appears that the device is freed from the poison pattern. [] get_rps_cpu+0x94/0x2f0 [] netif_rx_internal+0x140/0x1cc [] netif_rx+0x74/0x94 [] xfrm_input+0x754/0x7d0 [] xfrm_input_resume+0x10/0x1c [] esp_input_done+0x20/0x30 [] process_one_work+0x244/0x3fc [] worker_thread+0x2f8/0x418 [] kthread+0xe0/0xec -013|get_rps_cpu( | dev = 0xFFFFFFC08B688000, | skb = 0xFFFFFFC0C76AAC00 -> ( | dev = 0xFFFFFFC08B688000 -> ( | name = "...................................................... | name_hlist = (next = 0xAAAAAAAAAAAAAAAA, pprev = 0xAAAAAAAAAAA Following are the sequence of events observed - - Encrypted packet in receive path from netdevice is queued - Encrypted packet queued for decryption (asynchronous) - Netdevice brought down and freed - Packet is decrypted and returned through callback in esp_input_done - Packet is queued again for process in network stack using netif_rx Since the device appears to have been freed, the dereference of skb->dev in get_rps_cpus() leads to an unhandled page fault exception. Fix this by holding on to device reference when queueing packets asynchronously and releasing the reference on call back return. v2: Make the change generic to xfrm as mentioned by Steffen and update the title to xfrm Suggested-by: Herbert Xu Signed-off-by: Jerome Stanislaus Signed-off-by: Subash Abhinov Kasiviswanathan Signed-off-by: David S. Miller --- net/xfrm/xfrm_input.c | 3 +++ 1 file changed, 3 insertions(+) (limited to 'net/xfrm/xfrm_input.c') diff --git a/net/xfrm/xfrm_input.c b/net/xfrm/xfrm_input.c index ad7f5b3f9b61..1c4ad477ce93 100644 --- a/net/xfrm/xfrm_input.c +++ b/net/xfrm/xfrm_input.c @@ -292,12 +292,15 @@ int xfrm_input(struct sk_buff *skb, int nexthdr, __be32 spi, int encap_type) XFRM_SKB_CB(skb)->seq.input.hi = seq_hi; skb_dst_force(skb); + dev_hold(skb->dev); nexthdr = x->type->input(x, skb); if (nexthdr == -EINPROGRESS) return 0; resume: + dev_put(skb->dev); + spin_lock(&x->lock); if (nexthdr <= 0) { if (nexthdr == -EBADMSG) { -- cgit v1.2.3-59-g8ed1b