bpf: drop unnecessary user-triggerable WARN_ONCE in verifierl log

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: bpf: drop unnecessary user-triggerable WARN_ONCE in verifierl log It's trivial for user to trigger "verifier log line truncated" warning, as verifier has a fixed-sized buffer of 1024 bytes (as of now), and there are at least two pieces of user-provided information that can be output through this buffer, and both can be arbitrarily sized by user: - BTF names; - BTF.ext source code lines strings. Verifier log buffer should be properly sized for typical verifier state output. But it's sort-of expected that this buffer won't be long enough in some circumstances. So let's drop the check. In any case code will work correctly, at worst truncating a part of a single line output.

References

• https://git.kernel.org/stable/c/40c88c429a598006f91ad7a2b89856cd50b3a008
• https://git.kernel.org/stable/c/926a175026fed5d534f587ea4ec3ec49265cd3c5
• https://git.kernel.org/stable/c/cff36398bd4c7d322d424433db437f3c3391c491