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

Greg Kroah-Hartman
2020-01-22T13:23:32Z

From: Martin KaFai Lau <kafai@fb.com>

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@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Reviewed-by: Quentin Monnet <quentin.monnet@netronome.com>
Link: https://lore.kernel.org/bpf/20200110231644.3484151-1-kafai@fb.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
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);
}