Commit 343eba69 authored Jun 10, 2017 by Jia-Ju Bai Committed by David S. Miller Jun 10, 2017

net: tipc: Fix a sleep-in-atomic bug in tipc_msg_reverse



The kernel may sleep under a rcu read lock in tipc_msg_reverse, and the
function call path is:
tipc_l2_rcv_msg (acquire the lock by rcu_read_lock)
  tipc_rcv
    tipc_sk_rcv
      tipc_msg_reverse
        pskb_expand_head(GFP_KERNEL) --> may sleep
tipc_node_broadcast
  tipc_node_xmit_skb
    tipc_node_xmit
      tipc_sk_rcv
        tipc_msg_reverse
          pskb_expand_head(GFP_KERNEL) --> may sleep

To fix it, "GFP_KERNEL" is replaced with "GFP_ATOMIC".

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

parent f146e872

net/tipc/msg.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -508,7 +508,7 @@ bool tipc_msg_reverse(u32 own_node, struct sk_buff **skb, int err)
		}

		if (skb_cloned(_skb) &&
		pskb_expand_head(_skb, BUF_HEADROOM, BUF_TAILROOM, GFP_KERNEL))
		pskb_expand_head(_skb, BUF_HEADROOM, BUF_TAILROOM, GFP_ATOMIC))
		goto exit;

		/* Now reverse the concerned fields */

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