linux-kernel - [PATCH 5.6 044/126] ceph: fix double unlock in handle_cap

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Date:   Tue, 26 May 2020 20:53:01 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Wu Bo <wubo40@...wei.com>,
        "Yan, Zheng" <zyan@...hat.com>, Ilya Dryomov <idryomov@...il.com>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.6 044/126] ceph: fix double unlock in handle_cap_export()

From: Wu Bo <wubo40@...wei.com>

[ Upstream commit 4d8e28ff3106b093d98bfd2eceb9b430c70a8758 ]

If the ceph_mdsc_open_export_target_session() return fails, it will
do a "goto retry", but the session mutex has already been unlocked.
Re-lock the mutex in that case to ensure that we don't unlock it
twice.

Signed-off-by: Wu Bo <wubo40@...wei.com>
Reviewed-by: "Yan, Zheng" <zyan@...hat.com>
Signed-off-by: Ilya Dryomov <idryomov@...il.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 fs/ceph/caps.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/fs/ceph/caps.c b/fs/ceph/caps.c
index d050acc1fd5d..f50204380a65 100644
--- a/fs/ceph/caps.c
+++ b/fs/ceph/caps.c
@@ -3707,6 +3707,7 @@ retry:
 		WARN_ON(1);
 		tsession = NULL;
 		target = -1;
+		mutex_lock(&session->s_mutex);
 	}
 	goto retry;
 
-- 
2.25.1