SUNRPC: lock against ->sock changing during sysfs read
->sock can be set to NULL asynchronously unless ->recv_mutex is held.
So it is important to hold that mutex. Otherwise a sysfs read can
trigger an oops.
Commit 17f09d3f619a ("SUNRPC: Check if the xprt is connected before
handling sysfs reads") appears to attempt to fix this problem, but it
only narrows the race window.
Fixes: 17f09d3f619a ("SUNRPC: Check if the xprt is connected before handling sysfs reads")
Fixes: a8482488a7d6 ("SUNRPC query transport's source port")
Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
diff --git a/net/sunrpc/sysfs.c b/net/sunrpc/sysfs.c
index b64a028..05c758d 100644
--- a/net/sunrpc/sysfs.c
+++ b/net/sunrpc/sysfs.c
@@ -115,11 +115,14 @@ static ssize_t rpc_sysfs_xprt_srcaddr_show(struct kobject *kobj,
}
sock = container_of(xprt, struct sock_xprt, xprt);
- if (kernel_getsockname(sock->sock, (struct sockaddr *)&saddr) < 0)
+ mutex_lock(&sock->recv_mutex);
+ if (sock->sock == NULL ||
+ kernel_getsockname(sock->sock, (struct sockaddr *)&saddr) < 0)
goto out;
ret = sprintf(buf, "%pISc\n", &saddr);
out:
+ mutex_unlock(&sock->recv_mutex);
xprt_put(xprt);
return ret + 1;
}