[PATCH 5.4 134/222] bpftool: Fix printing incorrect pointer in btf_dump_ptr

[Greg Kroah-Hartman]

From: Martin KaFai Lau <kafai@xxxxxx>

commit 555089fdfc37ad65e0ee9b42ca40c238ff546f83 upstream.

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()")
Signed-off-by: Martin KaFai Lau <kafai@xxxxxx>
Signed-off-by: Alexei Starovoitov <ast@xxxxxxxxxx>
Reviewed-by: Quentin Monnet <quentin.monnet@xxxxxxxxxxxxx>
Link: https://lore.kernel.org/bpf/20200110231644.3484151-1-kafai@xxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

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

--- 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 *d
 			   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);
 }