lib: bpf_legacy: treat 0 as a valid file descriptor

As stated in the man page(), open returns a non-negative integer as a
file descriptor. Hence, when checking for its return value to be ok, we
should include 0 as a valid value.

This fixes a covscan warning about a missing close() in this function.

Fixes: ecb05c0f99 ("bpf: improve error reporting around tail calls")
Signed-off-by: Andrea Claudi <aclaudi@redhat.com>
Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>

lib/bpf_legacy.c

@@ -2832,7 +2832,7 @@ static void bpf_get_cfg(struct bpf_elf_ctx *ctx)
 	int fd;
 
 	fd = open(path_jit, O_RDONLY);
-	if (fd > 0) {
+	if (fd >= 0) {
 		char tmp[16] = {};
 
 		if (read(fd, tmp, sizeof(tmp)) > 0)