bpftool: Avoid leaking the JSON writer prepared for program metadata
authorQuentin Monnet <quentin@isovalent.com>
Fri, 22 Oct 2021 09:47:43 +0000 (10:47 +0100)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Thu, 18 Nov 2021 18:16:39 +0000 (19:16 +0100)
commite6c63efb0c8d5e69a12247a3323612e168737e95
treee139b4508fd206d7b1017bc29d438e3cf24cfb1f
parent5d33132c03ff5b33bed76c412bad0af21b48320e
bpftool: Avoid leaking the JSON writer prepared for program metadata

[ 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