rpc: remove length assert in proto_read_attribute_buffer_array

[ZoltanFridrich]

Return an error when parsed_array_size < actual_array_size rather then crashing with assert in proto_read_attribute_buffer_array.

[coveralls]

coverage: 69.53% (-0.001%) from 69.531%
when pulling 88d13e8 on ZoltanFridrich:zfridric_devel
into f53bdc2 on p11-glue:master.

[ueno]

Should we try to avoid integer overflow (wrap around this case) at multiplication? Maybe adding a check like ULONG_MAX / length < sizeof (CK_ATTRIBUTE) might help.

[ZoltanFridrich]

Should we try to avoid integer overflow (wrap around this case) at multiplication? Maybe adding a check like ULONG_MAX / length < sizeof (CK_ATTRIBUTE) might help.

I think you meant ULONG_MAX / n_array < sizeof (CK_ATTRIBUTE). Thats a good idea. Fixed.