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Subject[PATCH] net: tipc: Fix a sleep-in-atomic bug in tipc_msg_reverse
Date
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>
---
net/tipc/msg.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/tipc/msg.c b/net/tipc/msg.c
index 312ef7d..ab30876 100644
--- a/net/tipc/msg.c
+++ b/net/tipc/msg.c
@@ -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 */
--
1.7.9.5

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