[Bug] Crashes at RemoteConfigResponse related to FlatBufferBuilder

[feixuwu]

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[REQUIRED] Please fill in the following fields:

• Pre-built SDK from the website or open-source from this repo: 10.3.0
• Firebase C++ SDK version: 10.3.0
• Main Firebase Components in concern: remote_config
• Other Firebase Components in use: auth
• Platform you are using the C++ SDK on: windows
• Platform you are targeting: windows

[REQUIRED] Please describe the question here:

hi, I found some crash on my customer's PC,
from the minidump, the crash is like this:

the rdx is zero

and the correspond code is

the rbx+68h get the builder_
the rax+170h use the builder_ get the buffer pointer,
the crash reason is GetRoot function will try use the buffer pointer from builder_,
but if the buffer pointer is null, it will crash,
so I think it should do some protect like this:

[google-oss-bot]

I couldn't figure out how to label this issue, so I've labeled it for a human to triage. Hang tight.

[chkuang-g]

Thank you for reporting this issue.

It is really odd that builder.GetBufferPointer() can return a null pointer. I'll mark this as a bug for now.

[triplef]

We’re seeing what looks like the same crash (in remote_config_response.cc:98). I’ve reported the details in #1433.

[triplef]

@chkuang-g do you have any update on this? We are seeing many users running into this on app launch when we initialize remote config. We collected all details in #1433, from what it looks like a thread safety issue.