Subject: [PATCH net] net: Check for fullsock in sock_i_uid()

From: Subash Abhinov Kasiviswanathan <[email-masked]>
Date: Tue, 1 Nov 2016 23:27:00 -0600

sock_i_uid() acquires the sk_callback_lock which does not exist
for sockets in TCP_NEW_SYN_RECV state. This results in errors
showing up as spinlock bad magic.

Signed-off-by: Subash Abhinov Kasiviswanathan <[email-masked]>
Cc: Eric Dumazet <[email-masked]>
---
 net/core/sock.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/net/core/sock.c b/net/core/sock.c
index c73e28f..af15ef0 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -1727,7 +1727,10 @@ void sock_efree(struct sk_buff *skb)
 
 kuid_t sock_i_uid(struct sock *sk)
 {
-	kuid_t uid;
+	kuid_t uid = GLOBAL_ROOT_UID;
+
+	if (!sk_fullsock(sk))
+		return uid;
 
 	read_lock_bh(&sk->sk_callback_lock);
 	uid = sk->sk_socket ? SOCK_INODE(sk->sk_socket)->i_uid : GLOBAL_ROOT_UID;
-- 
1.9.1