netdev.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
* [PATCH bpf-next] bpftool: avoid leaking the JSON writer prepared for program metadata
@ 2021-10-22  9:47 Quentin Monnet
  2021-10-22 23:50 ` patchwork-bot+netdevbpf
  0 siblings, 1 reply; 2+ messages in thread
From: Quentin Monnet @ 2021-10-22  9:47 UTC (permalink / raw)
  To: Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko
  Cc: netdev, bpf, Quentin Monnet, YiFei Zhu

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.

Cc: YiFei Zhu <zhuyifei@google.com>
Fixes: aff52e685eb3 ("bpftool: Support dumping metadata")
Signed-off-by: Quentin Monnet <quentin@isovalent.com>
---
 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 277d51c4c5d9..f633299b1261 100644
--- a/tools/bpf/bpftool/prog.c
+++ b/tools/bpf/bpftool/prog.c
@@ -307,18 +307,12 @@ 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);
@@ -328,6 +322,14 @@ 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;
 			}
 
-- 
2.30.2


^ permalink raw reply	[flat|nested] 2+ messages in thread

* Re: [PATCH bpf-next] bpftool: avoid leaking the JSON writer prepared for program metadata
  2021-10-22  9:47 [PATCH bpf-next] bpftool: avoid leaking the JSON writer prepared for program metadata Quentin Monnet
@ 2021-10-22 23:50 ` patchwork-bot+netdevbpf
  0 siblings, 0 replies; 2+ messages in thread
From: patchwork-bot+netdevbpf @ 2021-10-22 23:50 UTC (permalink / raw)
  To: Quentin Monnet; +Cc: ast, daniel, andrii, netdev, bpf, zhuyifei

Hello:

This patch was applied to bpf/bpf-next.git (master)
by Andrii Nakryiko <andrii@kernel.org>:

On Fri, 22 Oct 2021 10:47:43 +0100 you wrote:
> 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.
> 
> [...]

Here is the summary with links:
  - [bpf-next] bpftool: avoid leaking the JSON writer prepared for program metadata
    https://git.kernel.org/bpf/bpf-next/c/e89ef634f81c

You are awesome, thank you!
-- 
Deet-doot-dot, I am a bot.
https://korg.docs.kernel.org/patchwork/pwbot.html



^ permalink raw reply	[flat|nested] 2+ messages in thread

end of thread, other threads:[~2021-10-22 23:50 UTC | newest]

Thread overview: 2+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2021-10-22  9:47 [PATCH bpf-next] bpftool: avoid leaking the JSON writer prepared for program metadata Quentin Monnet
2021-10-22 23:50 ` patchwork-bot+netdevbpf

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).