Fix boundary checks

[mauriciovasquezbernal]

• Add missing check on pkg/runtime/grpc/grpc-runtime.go
• Use ParseInt() instead of ParseUint() in pkg/gadgets/snapshot/process/tracer/tracer.go

https://github.com/inspektor-gadget/inspektor-gadget/security/code-scanning/12
https://github.com/inspektor-gadget/inspektor-gadget/security/code-scanning/13
https://github.com/inspektor-gadget/inspektor-gadget/security/code-scanning/14

Fixes: 2ad8b61 ("pkg: Add bound checks for integer converted by strconv functions.")

[eiffel-fl]

Hi!

Glad you understood how to fix these!
These reports are cool but I sometimes find them cryptic.
I just find some nits, otherwise you can merge it.

Best regards.

[mauriciovasquezbernal]

I'm still not totally convinced with the solution in pkg/runtime/grpc/grpc-runtime.go. I don't think we should be making extra validations there as this is already done in the params library:

inspektor-gadget/pkg/params/validators.go

Line 55 in 303c5ce

TypeUint: ValidateUint(strconv.IntSize),

I'm not totally sure what's the error being reported by codeql, I think about two possibilities:

1. Lack of error check of strconv.ParseUint in params.AsUint, should we panic if there is an error? (@flyth)
2. CodeQL has a right point that an uint to int64 conversion without a higher bound check is incorrect, perhaps this parameter could just be a uint16? (I don't think anybody will use a timeout higher than 2^16)

I think for the sake of simplicity on this PR, I'll go for option 2.