Commit 62039c30 authored Mar 09, 2020 by Andrii Nakryiko Committed by Alexei Starovoitov Mar 09, 2020

bpf: Initialize storage pointers to NULL to prevent freeing garbage pointer

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: 8bad74f9 ("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

parent 93e5fbb1

kernel/bpf/cgroup.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -302,8 +302,8 @@ int __cgroup_bpf_attach(struct cgroup cgrp, struct bpf_prog prog,
		u32 saved_flags = (flags & (BPF_F_ALLOW_OVERRIDE \| BPF_F_ALLOW_MULTI));
		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] = {};
		struct bpf_prog_list pl, replace_pl = NULL;
		enum bpf_cgroup_storage_type stype;
		int err;