selftests/bpf: Increase invalid metadata size

Changed check expects passed data meta to be deemed invalid. After loosening
the requirement, the size of 36 bytes becomes valid. Therefore, increase
tested meta size to 256, so we do not get an unexpected success.
Signed-off-by: Larysa Zaremba <larysa.zaremba@intel.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20231206205919.404415-2-larysa.zaremba@intel.com

tools/testing/selftests/bpf/prog_tests/xdp_context_test_run.c

@@ -77,8 +77,8 @@ void test_xdp_context_test_run(void)
 	test_xdp_context_error(prog_fd, opts, 4, sizeof(__u32), sizeof(data),
 			       0, 0, 0);
 
-	/* Meta data must be 32 bytes or smaller */
-	test_xdp_context_error(prog_fd, opts, 0, 36, sizeof(data), 0, 0, 0);
+	/* Meta data must be 255 bytes or smaller */
+	test_xdp_context_error(prog_fd, opts, 0, 256, sizeof(data), 0, 0, 0);
 
 	/* Total size of data must match data_end - data_meta */
 	test_xdp_context_error(prog_fd, opts, 0, sizeof(__u32),