[PATCH v2 1/1] xfrm : lock input tasklet skb queue
From: Tom Rix <trix@redhat.com>
Date: 2019-10-23 00:22:20
Also in:
lkml
Subsystem:
networking [general], networking [ipsec], the rest · Maintainers:
"David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Steffen Klassert, Herbert Xu, Linus Torvalds
On PREEMPT_RT_FULL while running netperf, a corruption
of the skb queue causes an oops.
This appears to be caused by a race condition here
__skb_queue_tail(&trans->queue, skb);
tasklet_schedule(&trans->tasklet);
Where the queue is changed before the tasklet is locked by
tasklet_schedule.
The fix is to use the skb queue lock.
This is the original work of Joerg Vehlow [off-list ref]
https://lkml.org/lkml/2019/9/9/111
xfrm_input: Protect queue with lock
During the skb_queue_splice_init the tasklet could have been preempted
and __skb_queue_tail called, which led to an inconsistent queue.
ifdefs for CONFIG_PREEMPT_RT_FULL added to reduce runtime effects
on the normal kernel.
Signed-off-by: Tom Rix <trix@redhat.com>
---
net/xfrm/xfrm_input.c | 18 +++++++++++++++++-
1 file changed, 17 insertions(+), 1 deletion(-)
diff --git a/net/xfrm/xfrm_input.c b/net/xfrm/xfrm_input.c
index 9b599ed66d97..decd515f84cf 100644
--- a/net/xfrm/xfrm_input.c
+++ b/net/xfrm/xfrm_input.c@@ -755,13 +755,21 @@ EXPORT_SYMBOL(xfrm_input_resume); static void xfrm_trans_reinject(unsigned long data) { +#ifdef CONFIG_PREEMPT_RT_FULL + unsigned long flags; +#endif struct xfrm_trans_tasklet *trans = (void *)data; struct sk_buff_head queue; struct sk_buff *skb; __skb_queue_head_init(&queue); +#ifdef CONFIG_PREEMPT_RT_FULL + spin_lock_irqsave(&trans->queue.lock, flags); +#endif skb_queue_splice_init(&trans->queue, &queue); - +#ifdef CONFIG_PREEMPT_RT_FULL + spin_unlock_irqrestore(&trans->queue.lock, flags); +#endif while ((skb = __skb_dequeue(&queue))) XFRM_TRANS_SKB_CB(skb)->finish(dev_net(skb->dev), NULL, skb); }
@@ -778,7 +786,11 @@ int xfrm_trans_queue(struct sk_buff *skb, return -ENOBUFS; XFRM_TRANS_SKB_CB(skb)->finish = finish; +#ifdef CONFIG_PREEMPT_RT_FULL + skb_queue_tail(&trans->queue, skb); +#else __skb_queue_tail(&trans->queue, skb); +#endif tasklet_schedule(&trans->tasklet); return 0; }
@@ -798,7 +810,11 @@ void __init xfrm_input_init(void) struct xfrm_trans_tasklet *trans; trans = &per_cpu(xfrm_trans_tasklet, i); +#ifdef CONFIG_PREEMPT_RT_FULL + skb_queue_head_init(&trans->queue); +#else __skb_queue_head_init(&trans->queue); +#endif tasklet_init(&trans->tasklet, xfrm_trans_reinject, (unsigned long)trans); }
--
2.23.0