linux-kernel - [PATCH] driver core: auxiliary bus: Fix auxiliary bus shutdown null auxdrv ptr

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Date:   Fri, 04 Dec 2020 09:46:49 -0700
From:   Dave Jiang <dave.jiang@...el.com>
To:     gregkh@...uxfoundation.org
Cc:     linux-kernel@...r.kernel.org, david.m.ertman@...el.com,
        dan.j.williams@...el.com
Subject: [PATCH] driver core: auxiliary bus: Fix auxiliary bus shutdown null
 auxdrv ptr

If the probe of the auxdrv failed, the device->driver is set to NULL.
During kernel shutdown, the bus shutdown will call auxdrv->shutdown and
cause an invalid ptr dereference. Add check to make sure device->driver is
not NULL before we proceed.

Fixes: 7de3697e9cbd ("Add auxiliary bus support")
Cc: Dave Ertman <david.m.ertman@...el.com>
Signed-off-by: Dave Jiang <dave.jiang@...el.com>
Reviewed-by: Dan Williams <dan.j.williams@...el.com>
---
 drivers/base/auxiliary.c |   11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/drivers/base/auxiliary.c b/drivers/base/auxiliary.c
index f303daadf843..8336535f1e11 100644
--- a/drivers/base/auxiliary.c
+++ b/drivers/base/auxiliary.c
@@ -92,10 +92,15 @@ static int auxiliary_bus_remove(struct device *dev)
 
 static void auxiliary_bus_shutdown(struct device *dev)
 {
-	struct auxiliary_driver *auxdrv = to_auxiliary_drv(dev->driver);
-	struct auxiliary_device *auxdev = to_auxiliary_dev(dev);
+	struct auxiliary_driver *auxdrv = NULL;
+	struct auxiliary_device *auxdev;
+
+	if (dev->driver) {
+		auxdrv = to_auxiliary_drv(dev->driver);
+		auxdev = to_auxiliary_dev(dev);
+	}
 
-	if (auxdrv->shutdown)
+	if (auxdrv && auxdrv->shutdown)
 		auxdrv->shutdown(auxdev);
 }