From: Gustavo A. R. Silva <garsilva@embeddedor.com>
Date: Thu, 11 May 2017 15:27:35 +0000 (-0500)
Subject: block: xen-blkback: add null check to avoid null pointer dereference
X-Git-Tag: v4.1.12-111.0.20170918_2215~217
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=e52857c45f3f03671ee974ebf1c0c287aaa7f9be;p=users%2Fjedix%2Flinux-maple.git

block: xen-blkback: add null check to avoid null pointer dereference

Add null check before calling xen_blkif_put() to avoid potential
null pointer dereference.

Addresses-Coverity-ID: 1350942
Cc: Juergen Gross <jgross@suse.com>
Signed-off-by: Gustavo A. R. Silva <garsilva@embeddedor.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

OraBug: 26662731

(cherry picked from commit 2d4456c73a487abe53863e10641c2f73537edf5c)
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Reviewed-by: Joao Martins <joao.m.martins@oracle.com>
---

diff --git a/drivers/block/xen-blkback/xenbus.c b/drivers/block/xen-blkback/xenbus.c
index 080292b3f83f5..79b0a9fea347e 100644
--- a/drivers/block/xen-blkback/xenbus.c
+++ b/drivers/block/xen-blkback/xenbus.c
@@ -508,11 +508,13 @@ static int xen_blkbk_remove(struct xenbus_device *dev)
 
 	dev_set_drvdata(&dev->dev, NULL);
 
-	if (be->blkif)
+	if (be->blkif) {
 		xen_blkif_disconnect(be->blkif);
 
-	/* Put the reference we set in xen_blkif_alloc(). */
-	xen_blkif_put(be->blkif);
+		/* Put the reference we set in xen_blkif_alloc(). */
+		xen_blkif_put(be->blkif);
+	}
+
 	kfree(be->mode);
 	kfree(be);
 	return 0;