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From: Martin KaFai Lau <kafai@fb.com>
To: <bpf@vger.kernel.org>
Cc: Alexei Starovoitov <ast@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	David Miller <davem@davemloft.net>, <kernel-team@fb.com>,
	<netdev@vger.kernel.org>,
	Quentin Monnet <quentin.monnet@netronome.com>
Subject: [PATCH bpf] bpftool: Fix printing incorrect pointer in btf_dump_ptr
Date: Fri, 10 Jan 2020 15:16:44 -0800	[thread overview]
Message-ID: <20200110231644.3484151-1-kafai@fb.com> (raw)

For plain text output, it incorrectly prints the pointer value
"void *data".  The "void *data" is actually pointing to memory that
contains a bpf-map's value.  The intention is to print the content of
the bpf-map's value instead of printing the pointer pointing to the
bpf-map's value.

In this case, a member of the bpf-map's value is a pointer type.
Thus, it should print the "*(void **)data".

Fixes: 22c349e8db89 ("tools: bpftool: fix format strings and arguments for jsonw_printf()")
Cc: Quentin Monnet <quentin.monnet@netronome.com>
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
---
 tools/bpf/bpftool/btf_dumper.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/bpf/bpftool/btf_dumper.c b/tools/bpf/bpftool/btf_dumper.c
index d66131f69689..397e5716ab6d 100644
--- a/tools/bpf/bpftool/btf_dumper.c
+++ b/tools/bpf/bpftool/btf_dumper.c
@@ -26,7 +26,7 @@ static void btf_dumper_ptr(const void *data, json_writer_t *jw,
 			   bool is_plain_text)
 {
 	if (is_plain_text)
-		jsonw_printf(jw, "%p", data);
+		jsonw_printf(jw, "%p", *(void **)data);
 	else
 		jsonw_printf(jw, "%lu", *(unsigned long *)data);
 }
-- 
2.17.1


             reply	other threads:[~2020-01-10 23:16 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-01-10 23:16 Martin KaFai Lau [this message]
2020-01-11 20:07 ` [PATCH bpf] bpftool: Fix printing incorrect pointer in btf_dump_ptr Quentin Monnet
2020-01-12  3:09   ` Alexei Starovoitov

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