dmaengine: idxd: Fix a possible NULL pointer dereference

'device_driver_attach()' dereferences its first argument (i.e. 'alt_drv')
so it must not be NULL.
Simplify the error handling logic about NULL 'alt_drv' in order to be
more robust and future-proof.

Fixes: 568b2126466f ("dmaengine: idxd: fix uninit var for alt_drv")
Fixes: 6e7f3ee97bbe ("dmaengine: idxd: move dsa_drv support to compatible mode")
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Acked-by: Dave Jiang <dave.jiang@intel.com>
Link: https://lore.kernel.org/r/77f0dc4f3966591d1f0cffb614a94085f8895a85.1627560174.git.christophe.jaillet@wanadoo.fr
Signed-off-by: Vinod Koul <vkoul@kernel.org>

diff --git a/drivers/dma/idxd/compat.c b/drivers/dma/idxd/compat.c
index d7616c240dcd41be44883ff37f45eefa3eb8bae6..3df21615f8883454d04ae7d84c6e18f4d4c6364d 100644 (file)
--- a/drivers/dma/idxd/compat.c
+++ b/drivers/dma/idxd/compat.c
@@ -45,23 +45,16 @@ static ssize_t bind_store(struct device_driver *drv, const char *buf, size_t cou
        idxd_dev = confdev_to_idxd_dev(dev);
        if (is_idxd_dev(idxd_dev)) {
                alt_drv = driver_find("idxd", bus);
-               if (!alt_drv)
-                       return -ENODEV;
        } else if (is_idxd_wq_dev(idxd_dev)) {
                struct idxd_wq *wq = confdev_to_wq(dev);
 
-               if (is_idxd_wq_kernel(wq)) {
+               if (is_idxd_wq_kernel(wq))
                        alt_drv = driver_find("dmaengine", bus);
-                       if (!alt_drv)
-                               return -ENODEV;
-               } else if (is_idxd_wq_user(wq)) {
+               else if (is_idxd_wq_user(wq))
                        alt_drv = driver_find("user", bus);
-                       if (!alt_drv)
-                               return -ENODEV;
-               } else {
-                       return -ENODEV;
-               }
        }
+       if (!alt_drv)
+               return -ENODEV;
 
        rc = device_driver_attach(alt_drv, dev);
        if (rc < 0)