| From | Luis Henriques <> | Subject | [PATCH 3.16.y-ckt 47/94] xen-blkfront: check for null drvdata in blkback_changed (XenbusStateClosing) | Date | Fri, 13 Nov 2015 10:09:41 +0000 |
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3.16.7-ckt20 -stable review patch. If anyone has any objections, please let me know.
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From: Cathy Avery <cathy.avery@oracle.com>
commit a54c8f0f2d7df525ff997e2afe71866a1a013064 upstream.
xen-blkfront will crash if the check to talk_to_blkback() in blkback_changed()(XenbusStateInitWait) returns an error. The driver data is freed and info is set to NULL. Later during the close process via talk_to_blkback's call to xenbus_dev_fatal() the null pointer is passed to and dereference in blkfront_closing.
Signed-off-by: Cathy Avery <cathy.avery@oracle.com> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Signed-off-by: Luis Henriques <luis.henriques@canonical.com> --- drivers/block/xen-blkfront.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c index 2a29cf69cd73..1b683dbc3f88 100644 --- a/drivers/block/xen-blkfront.c +++ b/drivers/block/xen-blkfront.c @@ -1905,7 +1905,8 @@ static void blkback_changed(struct xenbus_device *dev, break; /* Missed the backend's Closing state -- fallthrough */ case XenbusStateClosing: - blkfront_closing(info); + if (info) + blkfront_closing(info); break; } }
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