Claude review: scripts: modpost: detect and report truncated buf_printf() output

[Claude Code Review Bot <claude-review@example.com>]

Patch Review

**Correctness fix is needed.** The patch correctly identifies that `vsnprintf()` returning `len >= SZ` means the output was truncated and `buf_write()` would read `len` bytes from a `SZ`-sized stack buffer — a buffer over-read.

However, the error message has a problem:

```c
if (len >= SZ)
    fatal("buf_printf output truncated for string %s: %d bytes needed, %d available\n",
          tmp, len + 1, SZ);
```

When `len >= SZ`, `tmp` contains a **truncated**, null-terminated string. Printing it via `%s` is technically safe (it's still null-terminated by `vsnprintf()`), but the message says "for string %s" which shows the *truncated* output, not the full intended string. This is probably good enough for debugging — you'll see the start of the symbol name — but the message could be slightly misleading. Consider adding a note like `(truncated)` to the output.

Also, the `va_end(ap)` was moved before the truncation check, which is correct — `va_end` should be called before `exit(1)` or `fatal()` to ensure proper cleanup. Good.

Minor style: the kernel modpost code doesn't seem to use braces around single-statement `if` bodies elsewhere, but consistency with the existing `if (len < 0)` block (which does use braces) is fine.

**No blocking issues.**

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Generated by Claude Code Patch Reviewer