From: Roman Gushchin <guro@fb.com>
Date: Tue, 2 Oct 2018 02:41:53 +0000
Subject: bpf: don't accept cgroup local storage with zero value size
Patch-mainline: v4.19-rc7
Git-commit: b0584ea66d73919cbf5878a3420a837f06ab8396
References: bsc#1109837

Explicitly forbid creating cgroup local storage maps with zero value
size, as it makes no sense and might even cause a panic.

Reported-by: syzbot+18628320d3b14a5c459c@syzkaller.appspotmail.com
Signed-off-by: Roman Gushchin <guro@fb.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 kernel/bpf/local_storage.c |    3 +++
 1 file changed, 3 insertions(+)

--- a/kernel/bpf/local_storage.c
+++ b/kernel/bpf/local_storage.c
@@ -195,6 +195,9 @@ static struct bpf_map *cgroup_storage_ma
 	if (attr->key_size != sizeof(struct bpf_cgroup_storage_key))
 		return ERR_PTR(-EINVAL);
 
+	if (attr->value_size == 0)
+		return ERR_PTR(-EINVAL);
+
 	if (attr->value_size > PAGE_SIZE)
 		return ERR_PTR(-E2BIG);