input: avoid negative input device numbers

Hi,
currently I discovered the possibility that device file numbers of the input subsystem could go negative when the signed int "border" is passed. To fix this behaviour I sent a patch a few minutes ago.

But as the subject says there is currently the (theoretical) possibility that the same input device file name is given out twice. This can happen if the "input_no" variable had an overflow (due to the fact this is at least at 2^32 I call the issue theoretical). If such a case occurs a -EEXISTS is returned at the creation of the file.

IMHO it would be a good idea to check if the chosen input device file name is valid at the point it is created (which is currently input_allocate_device). So you can just increment and check it again until there's a valid number/name found for it.

I'm pretty new to the input subsystem, so what do you think about it? Any comments/ideas? Would there be a better place to do such checking?

From: Richard Leitner <[email protected]>

Fix the format string for input device name generation to avoid negative device numbers when the id exceeds the maximum signed integer value.

Signed-off-by Richard Leitner <[email protected]>

---
 drivers/input/input.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

drivers/input/input.c +1 -1

index 236bc56..6be6982 100644
@@ -1791,7 +1791,7 @@ struct input_dev *input_allocate_device(void)
 		INIT_LIST_HEAD(&dev->h_list);
 		INIT_LIST_HEAD(&dev->node);
 
-		dev_set_name(&dev->dev, "input%ld",
+		dev_set_name(&dev->dev, "input%lu",
 			     (unsigned long) atomic_inc_return(&input_no) - 1);
 
 		__module_get(THIS_MODULE);

Signature · 1 line

2.1.1

Quoted 4 lines · Richard Leitner

From: Richard Leitner <[email protected]>

Fix the format string for input device name generation to avoid negative device numbers when the id exceeds the maximum signed integer value.

Well, it is going to take us a while to get there :)

Applied, thank you.

Quoted 7 lines · Dmitry Torokhov

Quoted 5 lines · Richard Leitner

From: Richard Leitner <[email protected]>

Fix the format string for input device name generation to avoid negative device numbers when the id exceeds the maximum signed integer value.

Quoted 3 lines

Well, it is going to take us a while to get there :)

Applied, thank you.

By the way, we have similar issue in serio and gameport code, mind sending fixes for them as well?