[PATCH 4.9 020/191] nfsd: Fix svc_xprt refcnt leak when setup callback client failed

Sasha Levin
2020-06-29T19:26:47Z

From: Xiyu Yang <xiyuyang19@fudan.edu.cn>

[ Upstream commit a4abc6b12eb1f7a533c2e7484cfa555454ff0977 ]

nfsd4_process_cb_update() invokes svc_xprt_get(), which increases the
refcount of the "c->cn_xprt".

The reference counting issue happens in one exception handling path of
nfsd4_process_cb_update(). When setup callback client failed, the
function forgets to decrease the refcnt increased by svc_xprt_get(),
causing a refcnt leak.

Fix this issue by calling svc_xprt_put() when setup callback client
failed.

Signed-off-by: Xiyu Yang <xiyuyang19@fudan.edu.cn>
Signed-off-by: Xin Tan <tanxin.ctf@gmail.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/nfsd/nfs4callback.c | 2 ++
1 file changed, 2 insertions(+)

diff --git a/fs/nfsd/nfs4callback.c b/fs/nfsd/nfs4callback.c
index 8d842282111be..172f697864ab5 100644
--- a/fs/nfsd/nfs4callback.c
+++ b/fs/nfsd/nfs4callback.c
@@ -1156,6 +1156,8 @@ static void nfsd4_process_cb_update(struct nfsd4_callback *cb)
err = setup_callback_client(clp, &conn, ses);
if (err) {
nfsd4_mark_cb_down(clp, err);
+ if (c)
+ svc_xprt_put(c->cn_xprt);
return;
}
}
--
2.25.1