Commit 9b85c2d4 authored Nov 28, 2017 by Quentin Monnet Committed by Daniel Borkmann Nov 30, 2017

tools: bpftool: fix crash on bad parameters with JSON



If bad or unrecognised parameters are specified after JSON output is
requested, `usage()` will try to output null JSON object before the
writer is created.

To prevent this, create the writer as soon as the `--json` option is
parsed.

Fixes: 004b45c0 ("tools: bpftool: provide JSON output for all possible commands")
Reported-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Quentin Monnet <quentin.monnet@netronome.com>
Acked-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

parent a39e17b2

tools/bpf/bpftool/main.c

+9 −10

Original line number	Diff line number	Diff line
		@@ -291,7 +291,15 @@ int main(int argc, char **argv)
		pretty_output = true;
		/* fall through */
		case 'j':
		if (!json_output) {
		json_wtr = jsonw_new(stdout);
		if (!json_wtr) {
		p_err("failed to create JSON writer");
		return -1;
		}
		json_output = true;
		}
		jsonw_pretty(json_wtr, pretty_output);
		break;
		case 'f':
		show_pinned = true;
		@@ -306,15 +314,6 @@ int main(int argc, char **argv)
		if (argc < 0)
		usage();

		if (json_output) {
		json_wtr = jsonw_new(stdout);
		if (!json_wtr) {
		p_err("failed to create JSON writer");
		return -1;
		}
		jsonw_pretty(json_wtr, pretty_output);
		}

		bfd_init();

		ret = cmd_select(cmds, argc, argv, do_help);

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