CVE-2025-38528

In the Linux kernel, the following vulnerability has been resolved:

bpf: Reject %p% format string in bprintf-like helpers

static const char fmt[] = "%p%";

bpf_trace_printk(fmt, sizeof(fmt));

The above BPF program isn't rejected and causes a kernel warning at

runtime:

Please remove unsupported %\x00 in format string

WARNING: CPU: 1 PID: 7244 at lib/vsprintf.c:2680 format_decode+0x49c/0x5d0

This happens because bpf_bprintf_prepare skips over the second %,

detected as punctuation, while processing %p. This patch fixes it by

not skipping over punctuation. %\x00 is then processed in the next

iteration and rejected.