netdev - [PATCH v2 bpf-next 1/5] bpftool: Fix a leak of btf object

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Date:   Wed, 15 Jan 2020 14:22:47 -0800
From:   Martin KaFai Lau <kafai@...com>
To:     <bpf@...r.kernel.org>
CC:     Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        David Miller <davem@...emloft.net>, <kernel-team@...com>,
        <netdev@...r.kernel.org>, Paul Chaignon <paul.chaignon@...nge.com>
Subject: [PATCH v2 bpf-next 1/5] bpftool: Fix a leak of btf object

When testing a map has btf or not, maps_have_btf() tests it by actually
getting a btf_fd from sys_bpf(BPF_BTF_GET_FD_BY_ID). However, it
forgot to btf__free() it.

In maps_have_btf() stage, there is no need to test it by really
calling sys_bpf(BPF_BTF_GET_FD_BY_ID). Testing non zero
info.btf_id is good enough.

Also, the err_close case is unnecessary, and also causes double
close() because the calling func do_dump() will close() all fds again.

Fixes: 99f9863a0c45 ("bpftool: Match maps by name")
Cc: Paul Chaignon <paul.chaignon@...nge.com>
Acked-by: Andrii Nakryiko <andriin@...com>
Signed-off-by: Martin KaFai Lau <kafai@...com>
---
 tools/bpf/bpftool/map.c | 16 ++--------------
 1 file changed, 2 insertions(+), 14 deletions(-)

diff --git a/tools/bpf/bpftool/map.c b/tools/bpf/bpftool/map.c
index c01f76fa6876..e00e9e19d6b7 100644
--- a/tools/bpf/bpftool/map.c
+++ b/tools/bpf/bpftool/map.c
@@ -915,32 +915,20 @@ static int maps_have_btf(int *fds, int nb_fds)
 {
 	struct bpf_map_info info = {};
 	__u32 len = sizeof(info);
-	struct btf *btf = NULL;
 	int err, i;
 
 	for (i = 0; i < nb_fds; i++) {
 		err = bpf_obj_get_info_by_fd(fds[i], &info, &len);
 		if (err) {
 			p_err("can't get map info: %s", strerror(errno));
-			goto err_close;
-		}
-
-		err = btf__get_from_id(info.btf_id, &btf);
-		if (err) {
-			p_err("failed to get btf");
-			goto err_close;
+			return -1;
 		}
 
-		if (!btf)
+		if (!info.btf_id)
 			return 0;
 	}
 
 	return 1;
-
-err_close:
-	for (; i < nb_fds; i++)
-		close(fds[i]);
-	return -1;
 }
 
 static int
-- 
2.17.1