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Message-Id: <1592051229-93898-1-git-send-email-xiyuyang19@fudan.edu.cn>
Date: Sat, 13 Jun 2020 20:27:09 +0800
From: Xiyu Yang <xiyuyang19@...an.edu.cn>
To: Steve French <sfrench@...ba.org>, linux-cifs@...r.kernel.org,
samba-technical@...ts.samba.org, linux-kernel@...r.kernel.org
Cc: yuanxzhang@...an.edu.cn, kjlu@....edu,
Xiyu Yang <xiyuyang19@...an.edu.cn>,
Xin Tan <tanxin.ctf@...il.com>
Subject: [PATCH] cifs: Fix cached_fid refcnt leak in open_shroot
open_shroot() invokes kref_get(), which increases the refcount of the
"tcon->crfid" object. When open_shroot() returns not zero, it means the
open operation failed and close_shroot() will not be called to decrement
the refcount of the "tcon->crfid".
The reference counting issue happens in one normal path of
open_shroot(). When the cached root have been opened successfully in a
concurrent process, the function increases the refcount and jump to
"oshr_free" to return. However the current return value "rc" may not
equal to 0, thus the increased refcount will not be balanced outside the
function, causing a refcnt leak.
Fix this issue by setting the value of "rc" to 0 before jumping to
"oshr_free" label.
Signed-off-by: Xiyu Yang <xiyuyang19@...an.edu.cn>
Signed-off-by: Xin Tan <tanxin.ctf@...il.com>
---
fs/cifs/smb2ops.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/fs/cifs/smb2ops.c b/fs/cifs/smb2ops.c
index 736d86b8a910..28553d45604e 100644
--- a/fs/cifs/smb2ops.c
+++ b/fs/cifs/smb2ops.c
@@ -763,6 +763,7 @@ int open_shroot(unsigned int xid, struct cifs_tcon *tcon,
/* close extra handle outside of crit sec */
SMB2_close(xid, tcon, fid.persistent_fid, fid.volatile_fid);
}
+ rc = 0;
goto oshr_free;
}
--
2.7.4
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