[UBJSON] Possible stream size exceeds QByteArray

[svenpilz]

Regarding the new UBJSON implementation.

The readSize function returns a size_t, while the resulting QByteArray takes an int as parameter. If size is greater then 2^31-1, then the constructor of QByteArray segfaults, because the int is negative.

See: gui/qubjson.cpp:160.

[jrfonseca]

I'll add a few checks.

But there's not much we can do to cope with that ATM. This is not the sole QByteArray use case of in qapitrace. QByteArray is used in a several places. So it will not cope with more than INT_MAX in neither of them.

Hopefully this won't happen in practice for a little longer.

But I can see this being a problem down the line -- sometimes we expand smaller pixels to 4xfloat when duping, which multiplies their size.

[jrfonseca]

I added an assert, and an URL to this issue. I'm sure this will happen again in the future, but now that we don't explode unsized internal formats so much, it should be OK for now.