[PATCH] [NET] replace __module_get by try_module_get in accept4

[Michal Hocko]

After 7f9a50a5b89b87f8e754f59ae9968da28be618a5 we are not checking for
potential BUG in module reference counting. Therefore we should replace
__module_get by try_module_get and BUG if the module is being unloaded.

Signed-off-by: Michal Hocko <mhocko@xxxxxxx>
---
 net/socket.c |    7 ++++---
 1 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/net/socket.c b/net/socket.c
index 35dd737..d0d4c92 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -1444,10 +1444,11 @@ SYSCALL_DEFINE4(accept4, int, fd, struct sockaddr __user *, upeer_sockaddr,
 	newsock->ops = sock->ops;
 
 	/*
-	 * We don't need try_module_get here, as the listening socket (sock)
-	 * has the protocol module (sock->ops->owner) held.
+	 * Socket's owner cannot be in unloading path because there
+	 * must be at least one listening reference
 	 */
-	__module_get(newsock->ops->owner);
+	if (unlikely(!try_module_get(newsock->ops->owner)))
+		BUG();
 
 	newfd = sock_alloc_fd(&newfile, flags & O_CLOEXEC);
 	if (unlikely(newfd < 0)) {
-- 
1.5.6.5


-- 
Michal Hocko
L3 team 
SUSE LINUX s.r.o.
Lihovarska 1060/12
190 00 Praha 9    
Czech Republic
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