Patch "net: tipc: Fix a sleep-in-atomic bug in tipc_msg_reverse" has been added to the 4.9-stable tree

This is a note to let you know that I've just added the patch titled

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

to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
net-tipc-fix-a-sleep-in-atomic-bug-in-tipc_msg_reverse.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Jia-Ju Bai <[email protected]>
Date: Sat, 10 Jun 2017 17:03:35 +0800
Subject: net: tipc: Fix a sleep-in-atomic bug in tipc_msg_reverse

From: Jia-Ju Bai <[email protected]>

[ Upstream commit 343eba69c6968190d8654b857aea952fed9a6749 ]

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".

---
 net/tipc/msg.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

@@ -508,7 +508,7 @@ bool tipc_msg_reverse(u32 own_node,  str
 	}
 
 	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 */

Patches currently in stable-queue which might be from [email protected] are

queue-4.9/net-tipc-fix-a-sleep-in-atomic-bug-in-tipc_msg_reverse.patch queue-4.9/net-caif-fix-a-sleep-in-atomic-bug-in-cfpkt_create_pfx.patch