Messages in this thread Patch in this message | | | From | Kamal Mostafa <> | Subject | [PATCH 4.2.y-ckt 17/93] xfrm: Fix crash observed during device unregistration and decryption | Date | Tue, 26 Apr 2016 11:16:17 -0700 |
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4.2.8-ckt9 -stable review patch. If anyone has any objections, please let me know.
---8<------------------------------------------------------------
From: "subashab@codeaurora.org" <subashab@codeaurora.org>
[ Upstream commit 071d36bf21bcc837be00cea55bcef8d129e7f609 ]
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.
[<ffffffc000af58ec>] get_rps_cpu+0x94/0x2f0 [<ffffffc000af5f94>] netif_rx_internal+0x140/0x1cc [<ffffffc000af6094>] netif_rx+0x74/0x94 [<ffffffc000bc0b6c>] xfrm_input+0x754/0x7d0 [<ffffffc000bc0bf8>] xfrm_input_resume+0x10/0x1c [<ffffffc000ba6eb8>] esp_input_done+0x20/0x30 [<ffffffc0000b64c8>] process_one_work+0x244/0x3fc [<ffffffc0000b7324>] worker_thread+0x2f8/0x418 [<ffffffc0000bb40c>] 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 <herbert@gondor.apana.org.au> Signed-off-by: Jerome Stanislaus <jeromes@codeaurora.org> Signed-off-by: Subash Abhinov Kasiviswanathan <subashab@codeaurora.org> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Kamal Mostafa <kamal@canonical.com> --- net/xfrm/xfrm_input.c | 3 +++ 1 file changed, 3 insertions(+)
diff --git a/net/xfrm/xfrm_input.c b/net/xfrm/xfrm_input.c index 60ce701..f32b959 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) { -- 2.7.4
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