linux-kernel - [PATCH 4.14 16/75] s390: vfio-ccw: Do not attempt to free no-op, test and tic cda.

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Date:   Thu,  7 Dec 2017 14:07:38 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        "Jason J. Herne" <jjherne@...ux.vnet.ibm.com>,
        Dong Jia Shi <bjsdjshi@...ux.vnet.ibm.com>,
        Pierre Morel <pmorel@...ux.vnet.ibm.com>,
        Halil Pasic <pasic@...ux.vnet.ibm.com>,
        Christian Borntraeger <borntraeger@...ibm.com>,
        Cornelia Huck <cohuck@...hat.com>,
        Sasha Levin <alexander.levin@...izon.com>
Subject: [PATCH 4.14 16/75] s390: vfio-ccw: Do not attempt to free no-op, test and tic cda.

4.14-stable review patch.  If anyone has any objections, please let me know.

------------------

From: "Jason J. Herne" <jjherne@...ux.vnet.ibm.com>


[ Upstream commit 408358b50deaf59b07c82a7bff8c7e7cce031fae ]

Because we do not make use of the cda (channel data address) for test,
no-op ccws no address translation takes place. This means cda could
contain a guest address which we do not want to attempt to free. Let's
check the command type and skip cda free when it is not needed.

For a TIC ccw, ccw->cda points to either a ccw in an existing chain or
it points to a whole new allocated chain. In either case the data will
be freed when the owning chain is freed.

Signed-off-by: Jason J. Herne <jjherne@...ux.vnet.ibm.com>
Reviewed-by: Dong Jia Shi <bjsdjshi@...ux.vnet.ibm.com>
Reviewed-by: Pierre Morel <pmorel@...ux.vnet.ibm.com>
Message-Id: <1510068152-21988-1-git-send-email-jjherne@...ux.vnet.ibm.com>
Reviewed-by: Halil Pasic <pasic@...ux.vnet.ibm.com>
Acked-by: Christian Borntraeger <borntraeger@...ibm.com>
Signed-off-by: Cornelia Huck <cohuck@...hat.com>
Signed-off-by: Sasha Levin <alexander.levin@...izon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 drivers/s390/cio/vfio_ccw_cp.c |    2 ++
 1 file changed, 2 insertions(+)

--- a/drivers/s390/cio/vfio_ccw_cp.c
+++ b/drivers/s390/cio/vfio_ccw_cp.c
@@ -330,6 +330,8 @@ static void ccwchain_cda_free(struct ccw
 {
 	struct ccw1 *ccw = chain->ch_ccw + idx;
 
+	if (ccw_is_test(ccw) || ccw_is_noop(ccw) || ccw_is_tic(ccw))
+		return;
 	if (!ccw->count)
 		return;