ata: pata_platform: Fix a NULL pointer dereference in __pata_platform_probe()

In __pata_platform_probe(), devm_kzalloc() is assigned to ap->ops and
there is a dereference of it right after that, which could introduce a
NULL pointer dereference bug.

Fix this by adding a NULL check of ap->ops.

This bug was found by a static analyzer.

Builds with 'make allyesconfig' show no new warnings,
and our static analyzer no longer warns about this code.

Fixes: f3d5e4f ("ata: pata_of_platform: Allow to use 16-bit wide data transfer")
Signed-off-by: Zhou Qingyang <[email protected]>
Signed-off-by: Damien Le Moal <[email protected]>
Reviewed-by: Sergey Shtylyov <[email protected]>

Author: zhou1615

drivers/ata/pata_platform.c

@@ -128,6 +128,8 @@ int __pata_platform_probe(struct device *dev, struct resource *io_res,
 	ap = host->ports[0];
 
 	ap->ops = devm_kzalloc(dev, sizeof(*ap->ops), GFP_KERNEL);
+	if (!ap->ops)
+		return -ENOMEM;
 	ap->ops->inherits = &ata_sff_port_ops;
 	ap->ops->cable_detect = ata_cable_unknown;
 	ap->ops->set_mode = pata_platform_set_mode;