[PATCH AUTOSEL 5.6 040/606] cifs: fix leaked reference on requeued write

Sasha Levin
2020-06-09T00:40:42Z

From: Adam McCoy <adam@forsedomani.com>

commit a48137996063d22ffba77e077425f49873856ca5 upstream.

Failed async writes that are requeued may not clean up a refcount
on the file, which can result in a leaked open. This scenario arises
very reliably when using persistent handles and a reconnect occurs
while writing.

cifs_writev_requeue only releases the reference if the write fails
(rc != 0). The server->ops->async_writev operation will take its own
reference, so the initial reference can always be released.

Signed-off-by: Adam McCoy <adam@forsedomani.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
CC: Stable <stable@vger.kernel.org>
Reviewed-by: Pavel Shilovsky <pshilov@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
fs/cifs/cifssmb.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/cifs/cifssmb.c b/fs/cifs/cifssmb.c
index 6f6fb3606a5d..a4545aa04efc 100644
--- a/fs/cifs/cifssmb.c
+++ b/fs/cifs/cifssmb.c
@@ -2138,8 +2138,8 @@ cifs_writev_requeue(struct cifs_writedata *wdata)
}
}

+ kref_put(&wdata2->refcount, cifs_writedata_release);
if (rc) {
- kref_put(&wdata2->refcount, cifs_writedata_release);
if (is_retryable_error(rc))
continue;
i += nr_pages;
--
2.25.1