staging/ipack: Fix bug introduced by IPack device matching

~0 can not be casted to u8.  Instead of using the IPACK_ANY_ID for the format
field we introduce a new IPACK_ANY_FORMAT specifically for that field and
defined as 0xff.
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Jens Taprogge <jens.taprogge@taprogge.org>
Acked-by: Samuel Iglesias Gonsálvez <siglesias@igalia.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/ipack/ipack.c

@@ -31,7 +31,8 @@ static inline const struct ipack_device_id *
 ipack_match_one_device(const struct ipack_device_id *id,
 		       const struct ipack_device *device)
 {
-	if ((id->format == IPACK_ANY_ID || id->format == device->id_format) &&
+	if ((id->format == IPACK_ANY_FORMAT ||
+				id->format == device->id_format) &&
 	    (id->vendor == IPACK_ANY_ID || id->vendor == device->id_vendor) &&
 	    (id->device == IPACK_ANY_ID || id->device == device->id_device))
 		return id;

include/linux/mod_devicetable.h

@@ -600,6 +600,7 @@ struct x86_cpu_id {
 #define X86_MODEL_ANY  0
 #define X86_FEATURE_ANY 0	/* Same as FPU, you can't test for that */
 
+#define IPACK_ANY_FORMAT 0xff
 #define IPACK_ANY_ID (~0)
 struct ipack_device_id {
 	__u8  format;			/* Format version or IPACK_ANY_ID */

scripts/mod/file2alias.c

@@ -973,7 +973,7 @@ static int do_ipack_entry(const char *filename,
 	id->vendor = TO_NATIVE(id->vendor);
 	id->device = TO_NATIVE(id->device);
 	strcpy(alias, "ipack:");
-	ADD(alias, "f", id->format != IPACK_ANY_ID, id->format);
+	ADD(alias, "f", id->format != IPACK_ANY_FORMAT, id->format);
 	ADD(alias, "v", id->vendor != IPACK_ANY_ID, id->vendor);
 	ADD(alias, "d", id->device != IPACK_ANY_ID, id->device);
 	add_wildcard(alias);