linux-kernel - [PATCH v2] libbpf: Fix NULL pointer exception in API btf_dump__dump_type

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Date:   Sat, 17 Sep 2022 16:48:09 +0800
From:   Xin Liu <liuxin350@...wei.com>
To:     <ast@...nel.org>, <daniel@...earbox.net>, <andrii@...nel.org>,
        <martin.lau@...ux.dev>, <song@...nel.org>, <yhs@...com>,
        <john.fastabend@...il.com>, <kpsingh@...nel.org>, <sdf@...gle.com>,
        <haoluo@...gle.com>, <jolsa@...nel.org>
CC:     <bpf@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <yanan@...wei.com>, <wuchangye@...wei.com>,
        <xiesongyang@...wei.com>, <zhudi2@...wei.com>,
        <kongweibin2@...wei.com>, <liuxin350@...wei.com>
Subject: [PATCH v2] libbpf: Fix NULL pointer exception in API btf_dump__dump_type_data

We found that function btf_dump__dump_type_data can be called by the
user as an API, but in this function, the `opts` parameter may be used
as a null pointer.This causes `opts->indent_str` to trigger a NULL
pointer exception.

Fixes: 2ce8450ef5a3 ("libbpf: add bpf_object__open_{file, mem} w/ extensible opts")
Signed-off-by: Xin Liu <liuxin350@...wei.com>
Signed-off-by: Weibin Kong <kongweibin2@...wei.com>
---
v1 -> v2: Use OPTS_GET to fix NULL pointer exceptions
v1: https://lore.kernel.org/bpf/20220914123423.24368-1-liuxin350@huawei.com/ 

 tools/lib/bpf/btf_dump.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/lib/bpf/btf_dump.c b/tools/lib/bpf/btf_dump.c
index 627edb5bb6de..4221f73a74d0 100644
--- a/tools/lib/bpf/btf_dump.c
+++ b/tools/lib/bpf/btf_dump.c
@@ -2385,7 +2385,7 @@ int btf_dump__dump_type_data(struct btf_dump *d, __u32 id,
 	d->typed_dump->indent_lvl = OPTS_GET(opts, indent_level, 0);
 
 	/* default indent string is a tab */
-	if (!opts->indent_str)
+	if (!OPTS_GET(opts, indent_str, NULL))
 		d->typed_dump->indent_str[0] = '\t';
 	else
 		libbpf_strlcpy(d->typed_dump->indent_str, opts->indent_str,
-- 
2.33.0