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 <herb...@gondor.apana.org.au>
Signed-off-by: Jerome Stanislaus <jero...@codeaurora.org>
Signed-off-by: Subash Abhinov Kasiviswanathan <subas...@codeaurora.org>
---
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 ad7f5b3..1c4ad47 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) {
--
