Input: iforce - invert valid length check when fetching device IDs

syzbot is reporting uninitialized value at iforce_init_device() [1], for
commit 6ac0aec ("Input: iforce - allow callers supply data buffer
when fetching device IDs") is checking that valid length is shorter than
bytes to read. Since iforce_get_id_packet() stores valid length when
returning 0, the caller needs to check that valid length is longer than or
equals to bytes to read.

Reported-by: syzbot <[email protected]>
Signed-off-by: Tetsuo Handa <[email protected]>
Fixes: 6ac0aec ("Input: iforce - allow callers supply data buffer when fetching device IDs")
Link: https://lore.kernel.org/r/[email protected]
Cc: [email protected]
Signed-off-by: Dmitry Torokhov <[email protected]>

Author: Tetsuo Handa

drivers/input/joystick/iforce/iforce-main.c

@@ -273,22 +273,22 @@ int iforce_init_device(struct device *parent, u16 bustype,
  * Get device info.
  */
 
-	if (!iforce_get_id_packet(iforce, 'M', buf, &len) || len < 3)
+	if (!iforce_get_id_packet(iforce, 'M', buf, &len) && len >= 3)
 		input_dev->id.vendor = get_unaligned_le16(buf + 1);
 	else
 		dev_warn(&iforce->dev->dev, "Device does not respond to id packet M\n");
 
-	if (!iforce_get_id_packet(iforce, 'P', buf, &len) || len < 3)
+	if (!iforce_get_id_packet(iforce, 'P', buf, &len) && len >= 3)
 		input_dev->id.product = get_unaligned_le16(buf + 1);
 	else
 		dev_warn(&iforce->dev->dev, "Device does not respond to id packet P\n");
 
-	if (!iforce_get_id_packet(iforce, 'B', buf, &len) || len < 3)
+	if (!iforce_get_id_packet(iforce, 'B', buf, &len) && len >= 3)
 		iforce->device_memory.end = get_unaligned_le16(buf + 1);
 	else
 		dev_warn(&iforce->dev->dev, "Device does not respond to id packet B\n");
 
-	if (!iforce_get_id_packet(iforce, 'N', buf, &len) || len < 2)
+	if (!iforce_get_id_packet(iforce, 'N', buf, &len) && len >= 2)
 		ff_effects = buf[1];
 	else
 		dev_warn(&iforce->dev->dev, "Device does not respond to id packet N\n");