tools resolve_btfids: Add size check to get_id function

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

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20200825192124.710397-2-jolsa@kernel.org

diff --git a/tools/bpf/resolve_btfids/main.c b/tools/bpf/resolve_btfids/main.c
index 4d9ecb9..35a172d 100644 (file)
--- 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