Subject: [PATCH v9 bpf-next 01/14] tools resolve_btfids: Add size check to get_id function

From: Jiri Olsa <[email-masked]>
Date: Sat, 1 Aug 2020 19:03:09 +0200

To make sure we don't crash on malformed symbols.

Signed-off-by: Jiri Olsa <[email-masked]>
---
 tools/bpf/resolve_btfids/main.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/tools/bpf/resolve_btfids/main.c b/tools/bpf/resolve_btfids/main.c
index 6956b6350cad..e0929620abc6 100644
--- a/tools/bpf/resolve_btfids/main.c
+++ b/tools/bpf/resolve_btfids/main.c
@@ -199,9 +199,16 @@ static char *get_id(const char *prefix_end)
 	/*
 	 * __BTF_ID__func__vfs_truncate__0
 	 * prefix_end =  ^
+	 * pos        =    ^
 	 */
-	char *p, *id = strdup(prefix_end + sizeof("__") - 1);
+	int len = strlen(prefix_end);
+	int pos = sizeof("__") - 1;
+	char *p, *id;
 
+	if (pos >= len)
+		return NULL;
+
+	id = strdup(prefix_end + pos);
 	if (id) {
 		/*
 		 * __BTF_ID__func__vfs_truncate__0
-- 
2.25.4