From: Quentin Monnet <quentin@isovalent.com>
Date: Fri, 24 Jul 2020 10:06:17 +0100
Subject: tools, bpftool: Skip type probe if name is not found
Patch-mainline: v5.9-rc1
Git-commit: 70cfab1d871c771bd1963dd898f4f9b2731590c2
References: bsc#1177028

For probing program and map types, bpftool loops on type values and uses
the relevant type name in prog_type_name[] or map_type_name[]. To ensure
the name exists, we exit from the loop if we go over the size of the
array.

However, this is not enough in the case where the arrays have "holes" in
them, program or map types for which they have no name, but not at the
end of the list. This is currently the case for BPF_PROG_TYPE_LSM, not
known to bpftool and which name is a null string. When probing for
features, bpftool attempts to strlen() that name and segfaults.

Let's fix it by skipping probes for "unknown" program and map types,
with an informational message giving the numeral value in that case.

Fixes: 93a3545d812a ("tools/bpftool: Add name mappings for SK_LOOKUP prog and attach type")
Reported-by: Paul Chaignon <paul@cilium.io>
Signed-off-by: Quentin Monnet <quentin@isovalent.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20200724090618.16378-2-quentin@isovalent.com
Acked-by: Gary Lin <glin@suse.com>
---
 tools/bpf/bpftool/feature.c |    8 ++++++++
 1 file changed, 8 insertions(+)

--- a/tools/bpf/bpftool/feature.c
+++ b/tools/bpf/bpftool/feature.c
@@ -504,6 +504,10 @@ probe_prog_type(enum bpf_prog_type prog_
 
 	supported_types[prog_type] |= res;
 
+	if (!prog_type_name[prog_type]) {
+		p_info("program type name not found (type %d)", prog_type);
+		return;
+	}
 	maxlen = sizeof(plain_desc) - strlen(plain_comment) - 1;
 	if (strlen(prog_type_name[prog_type]) > maxlen) {
 		p_info("program type name too long");
@@ -533,6 +537,10 @@ probe_map_type(enum bpf_map_type map_typ
 	 * check required for unprivileged users
 	 */
 
+	if (!map_type_name[map_type]) {
+		p_info("map type name not found (type %d)", map_type);
+		return;
+	}
 	maxlen = sizeof(plain_desc) - strlen(plain_comment) - 1;
 	if (strlen(map_type_name[map_type]) > maxlen) {
 		p_info("map type name too long");