From: Quentin Monnet quentin@isovalent.com
[ Upstream commit e89ef634f81c9d90e1824ab183721f3b361472e6 ]
Bpftool creates a new JSON object for writing program metadata in plain text mode, regardless of metadata being present or not. Then this writer is freed if any metadata has been found and printed, but it leaks otherwise. We cannot destroy the object unconditionally, because the destructor prints an undesirable line break. Instead, make sure the writer is created only after we have found program metadata to print.
Found with valgrind.
Fixes: aff52e685eb3 ("bpftool: Support dumping metadata") Signed-off-by: Quentin Monnet quentin@isovalent.com Signed-off-by: Andrii Nakryiko andrii@kernel.org Link: https://lore.kernel.org/bpf/20211022094743.11052-1-quentin@isovalent.com Signed-off-by: Sasha Levin sashal@kernel.org --- tools/bpf/bpftool/prog.c | 16 +++++++++------- 1 file changed, 9 insertions(+), 7 deletions(-)
diff --git a/tools/bpf/bpftool/prog.c b/tools/bpf/bpftool/prog.c index 9d709b4276655..a33238a100a0c 100644 --- a/tools/bpf/bpftool/prog.c +++ b/tools/bpf/bpftool/prog.c @@ -308,18 +308,12 @@ static void show_prog_metadata(int fd, __u32 num_maps) if (printed_header) jsonw_end_object(json_wtr); } else { - json_writer_t *btf_wtr = jsonw_new(stdout); + json_writer_t *btf_wtr; struct btf_dumper d = { .btf = btf, - .jw = btf_wtr, .is_plain_text = true, };
- if (!btf_wtr) { - p_err("jsonw alloc failed"); - goto out_free; - } - for (i = 0; i < vlen; i++, vsi++) { t_var = btf__type_by_id(btf, vsi->type); name = btf__name_by_offset(btf, t_var->name_off); @@ -329,6 +323,14 @@ static void show_prog_metadata(int fd, __u32 num_maps)
if (!printed_header) { printf("\tmetadata:"); + + btf_wtr = jsonw_new(stdout); + if (!btf_wtr) { + p_err("jsonw alloc failed"); + goto out_free; + } + d.jw = btf_wtr, + printed_header = true; }