dtrust-tool: Fix NULL dereference with pinpad

[Jakuje]

Thanks coverity:

CID 414970
CID 414971
CID 414972
CID 414973

Fixup #3026

Checklist

• PKCS#11 module is tested
• Windows minidriver is tested
• macOS tokend is tested

[Jakuje]

@hamarituc can you have a look if this works for you? Can you test the tool with pinpad reader?

[hamarituc]

@hamarituc can you have a look if this works for you? Can you test the tool with pinpad reader?

Good spot. That was a pratfall from my side, which shouldn't have happened 🙈.

I can confirm your patch fixes the SEGFAULT. You may cherry-pick hamarituc@694ad25 as the pin pad entry requires to specify minimum and maxium PIN length, which is reasonable for non pin pad cases, too.

But I was not able to successfully test it with my pin pad reader. It's a Cherry Secure Board with an integrated smart card readers. But I wasn't able to use the pin pad function of this keyboard in the past. I suppose it's an issue with my reader and not the dtrust-tool.

[Jakuje]

Thanks. Pulled your commit. I also had issues with pinpad readers so I do not have a good one to recommend.