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: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/kernel/bpf/cgroup.c b/kernel/bpf/cgroup.c
index 28c97aee6d8fae0234fa43360610e180a1535448..869e2e1860e844c74d2e4283401b76b371fa015b 100644 (file)
--- a/kernel/bpf/cgroup.c
+++ b/kernel/bpf/cgroup.c
@@ -303,8 +303,8 @@ 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;