Commit f146e872 authored Jun 10, 2017 by Jia-Ju Bai Committed by David S. Miller Jun 10, 2017

net: caif: Fix a sleep-in-atomic bug in cfpkt_create_pfx



The kernel may sleep under a rcu read lock in cfpkt_create_pfx, and the
function call path is:
cfcnfg_linkup_rsp (acquire the lock by rcu_read_lock)
  cfctrl_linkdown_req
    cfpkt_create
      cfpkt_create_pfx
        alloc_skb(GFP_KERNEL) --> may sleep
cfserl_receive (acquire the lock by rcu_read_lock)
  cfpkt_split
    cfpkt_create_pfx
      alloc_skb(GFP_KERNEL) --> may sleep

There is "in_interrupt" in cfpkt_create_pfx to decide use "GFP_KERNEL" or
"GFP_ATOMIC". In this situation, "GFP_KERNEL" is used because the function
is called under a rcu read lock, instead in interrupt.

To fix it, only "GFP_ATOMIC" is used in cfpkt_create_pfx.

Signed-off-by: Jia-Ju Bai <baijiaju1990@163.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent 5aa32f53

net/caif/cfpkt_skbuff.c

+1 −5

Original line number	Diff line number	Diff line
		@@ -81,11 +81,7 @@ static struct cfpkt *cfpkt_create_pfx(u16 len, u16 pfx)
		{
		struct sk_buff *skb;

		if (likely(in_interrupt()))
		skb = alloc_skb(len + pfx, GFP_ATOMIC);
		else
		skb = alloc_skb(len + pfx, GFP_KERNEL);

		if (unlikely(skb == NULL))
		return NULL;

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