linux-kernel - [PATCH 4.9 083/119] cxl: Fix error path on bad ioctl

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Date:   Mon, 12 Jun 2017 17:25:45 +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,
        Frederic Barrat <fbarrat@...ux.vnet.ibm.com>,
        Vaibhav Jain <vaibhav@...ux.vnet.ibm.com>,
        Andrew Donnellan <andrew.donnellan@....ibm.com>,
        Michael Ellerman <mpe@...erman.id.au>
Subject: [PATCH 4.9 083/119] cxl: Fix error path on bad ioctl

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

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

From: Frederic Barrat <fbarrat@...ux.vnet.ibm.com>

commit cec422c11caeeccae709e9942058b6b644ce434c upstream.

Fix error path if we can't copy user structure on CXL_IOCTL_START_WORK
ioctl. We shouldn't unlock the context status mutex as it was not
locked (yet).

Fixes: 0712dc7e73e5 ("cxl: Fix issues when unmapping contexts")
Signed-off-by: Frederic Barrat <fbarrat@...ux.vnet.ibm.com>
Reviewed-by: Vaibhav Jain <vaibhav@...ux.vnet.ibm.com>
Reviewed-by: Andrew Donnellan <andrew.donnellan@....ibm.com>
Signed-off-by: Michael Ellerman <mpe@...erman.id.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/misc/cxl/file.c |    7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)

--- a/drivers/misc/cxl/file.c
+++ b/drivers/misc/cxl/file.c
@@ -155,11 +155,8 @@ static long afu_ioctl_start_work(struct
 
 	/* Do this outside the status_mutex to avoid a circular dependency with
 	 * the locking in cxl_mmap_fault() */
-	if (copy_from_user(&work, uwork,
-			   sizeof(struct cxl_ioctl_start_work))) {
-		rc = -EFAULT;
-		goto out;
-	}
+	if (copy_from_user(&work, uwork, sizeof(work)))
+		return -EFAULT;
 
 	mutex_lock(&ctx->status_mutex);
 	if (ctx->status != OPENED) {