bpftool: Check malloc return value in mount_bpffs_for_pin

Fix and add a missing NULL check for the prior malloc() call.

Fixes: 49a086c2 ("bpftool: implement prog load command")
Signed-off-by: Tobias Klauser <tklauser@distanz.ch>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Quentin Monnet <quentin@isovalent.com>
Acked-by: Roman Gushchin <guro@fb.com>
Link: https://lore.kernel.org/bpf/20210715110609.29364-1-tklauser@distanz.ch

tools/bpf/bpftool/common.c

@@ -222,6 +222,11 @@ int mount_bpffs_for_pin(const char *name)
 	int err = 0;
 
 	file = malloc(strlen(name) + 1);
+	if (!file) {
+		p_err("mem alloc failed");
+		return -1;
+	}
+
 	strcpy(file, name);
 	dir = dirname(file);