Marcus Wichelmann wrote:
The open_tuntap helper function uses open() to get a file descriptor for
/dev/net/tun.
The open(2) manpage writes this about its return value:
On success, open(), openat(), and creat() return the new file
descriptor (a nonnegative integer). On error, -1 is returned and
errno is set to indicate the error.
This means that the fd > 0 assertion in the open_tuntap helper is
incorrect and should rather check for fd >= 0.
When running the BPF selftests locally, this incorrect assertion was not
an issue, but the BPF kernel-patches CI failed because of this:
open_tuntap:FAIL:open(/dev/net/tun) unexpected open(/dev/net/tun):
actual 0 <= expected 0
Signed-off-by: Marcus Wichelmann <redacted>
Reviewed-by: Willem de Bruijn <willemb@google.com>