From: Manjunath Patil <manjunath.b.patil@oracle.com>
Date: Tue, 30 Oct 2018 09:49:21 -0700
Subject: [PATCH] xen-blkfront: fix kernel panic with negotiate_mq error path
Git-commit: 6cc4a0863c9709c512280c64e698d68443ac8053
Patch-mainline: v4.20-rc2
References: bsc#1104967,FATE#325924
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
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info->nr_rings isn't adjusted in case of ENOMEM error from
negotiate_mq(). This leads to kernel panic in error path.
Typical call stack involving panic -
#8 page_fault at ffffffff8175936f
[exception RIP: blkif_free_ring+33]
RIP: ffffffffa0149491 RSP: ffff8804f7673c08 RFLAGS: 00010292
...
#9 blkif_free at ffffffffa0149aaa [xen_blkfront]
#10 talk_to_blkback at ffffffffa014c8cd [xen_blkfront]
#11 blkback_changed at ffffffffa014ea8b [xen_blkfront]
#12 xenbus_otherend_changed at ffffffff81424670
#13 backend_changed at ffffffff81426dc3
#14 xenwatch_thread at ffffffff81422f29
#15 kthread at ffffffff810abe6a
#16 ret_from_fork at ffffffff81754078
Cc: stable@vger.kernel.org
Fixes: 7ed8ce1c5fc7 ("xen-blkfront: move negotiate_mq to cover all cases of new VBDs")
Signed-off-by: Manjunath Patil <manjunath.b.patil@oracle.com>
Acked-by: Roger Pau Monné <roger.pau@citrix.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
Acked-by: Hannes Reinecke <hare@suse.com>
---
drivers/block/xen-blkfront.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c
index 9eea83ae01c6..9ac3999a55b7 100644
--- a/drivers/block/xen-blkfront.c
+++ b/drivers/block/xen-blkfront.c
@@ -1919,6 +1919,7 @@ static int negotiate_mq(struct blkfront_info *info)
info->rinfo = kzalloc(sizeof(struct blkfront_ring_info) * info->nr_rings, GFP_KERNEL);
if (!info->rinfo) {
xenbus_dev_fatal(info->xbdev, -ENOMEM, "allocating ring_info structure");
+ info->nr_rings = 0;
return -ENOMEM;
}
--
2.16.4