release/5.2.41/bpf-Initialize-storage-pointers-to-NULL-to-prevent-f.patch

From 739c5b5ceeef7e38c4bcb5d3165d4ed8e4829a4f Mon Sep 17 00:00:00 2001
From: Andrii Nakryiko <andriin@fb.com>
Date: Mon, 9 Mar 2020 15:27:55 -0700
Subject: [PATCH] bpf: Initialize storage pointers to NULL to prevent freeing
 garbage pointer

commit 62039c30c19dcab96621e074aeeb90da7100def7 upstream.

Local storage array isn't initialized, so if cgroup storage allocation fails
for BPF_CGROUP_STORAGE_SHARED, error handling code will attempt to free
uninitialized pointer for BPF_CGROUP_STORAGE_PERCPU storage type. Avoid this
by always initializing storage pointers to NULLs.

Fixes: 8bad74f9840f ("bpf: extend cgroup bpf core to allow multiple cgroup storage types")
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200309222756.1018737-1-andriin@fb.com
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>

diff --git a/kernel/bpf/cgroup.c b/kernel/bpf/cgroup.c
index 9c073a88374f..b6ad8cb50efc 100644
--- a/kernel/bpf/cgroup.c
+++ b/kernel/bpf/cgroup.c
@@ -239,8 +239,8 @@ int __cgroup_bpf_attach(struct cgroup *cgrp, struct bpf_prog *prog,
 {
 	struct list_head *progs = &cgrp->bpf.progs[type];
 	struct bpf_prog *old_prog = NULL;
-	struct bpf_cgroup_storage *storage[MAX_BPF_CGROUP_STORAGE_TYPE],
-		*old_storage[MAX_BPF_CGROUP_STORAGE_TYPE] = {NULL};
+	struct bpf_cgroup_storage *storage[MAX_BPF_CGROUP_STORAGE_TYPE] = {};
+	struct bpf_cgroup_storage *old_storage[MAX_BPF_CGROUP_STORAGE_TYPE] = {};
 	enum bpf_cgroup_storage_type stype;
 	struct bpf_prog_list *pl;
 	bool pl_was_allocated;
-- 
2.7.4