bpf: Reject oversized bpf_stream_vprintk output with -E2BIG

bstr_printf() returns the would-be length excluding the trailing NUL.
When that value is >= MAX_BPRINTF_BUF the message was truncated, but
bpf_stream_push_str() still tried to allocate with the inflated length
and failed with -ENOMEM. The boundary case of exactly MAX_BPRINTF_BUF
could also copy the trailing NUL into the stream element.

Reject such lengths with -E2BIG before charging stream capacity, and
tighten bpf_stream_elem_alloc() to accept only payloads strictly shorter
than the bprintf buffer.

Fixes: 5ab154f1463a ("bpf: Introduce BPF standard streams")
Signed-off-by: Jianlin Shi <shijianlin11@foxmail.com>
Link: https://lore.kernel.org/r/74387ae5024d7e2996095e97211430285095b525.1787492521.git.shijianlin11@foxmail.com
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>

0 files changed, 0 insertions, 0 deletions