netfilter: bpf: defer hook memory release until rcu readers are done

[ Upstream commit 24f90fa3994b992d1a09003a3db2599330a5232a ]

Yiming Qian reports UaF when concurrent process is dumping hooks via
nfnetlink_hooks:

BUG: KASAN: slab-use-after-free in nfnl_hook_dump_one.isra.0+0xe71/0x10f0
Read of size 8 at addr ffff888003edbf88 by task poc/79
Call Trace:
 <TASK>
 nfnl_hook_dump_one.isra.0+0xe71/0x10f0
 netlink_dump+0x554/0x12b0
 nfnl_hook_get+0x176/0x230
 [..]

Defer release until after concurrent readers have completed.

Reported-by: Yiming Qian <yimingqian591@gmail.com>
Fixes: 84601d6ee68a ("bpf: add bpf_link support for BPF_NETFILTER programs")
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/net/netfilter/nf_bpf_link.c b/net/netfilter/nf_bpf_link.c
index b5e4ca9026a8e401681fa1546e50769dfb09ec56..be5e8bd90a3ebcce55c9e4e25f751507488f3aa6 100644 (file)
--- a/net/netfilter/nf_bpf_link.c
+++ b/net/netfilter/nf_bpf_link.c
@@ -170,7 +170,7 @@ static int bpf_nf_link_update(struct bpf_link *link, struct bpf_prog *new_prog,
 
 static const struct bpf_link_ops bpf_nf_link_lops = {
        .release = bpf_nf_link_release,
-       .dealloc = bpf_nf_link_dealloc,
+       .dealloc_deferred = bpf_nf_link_dealloc,
        .detach = bpf_nf_link_detach,
        .show_fdinfo = bpf_nf_link_show_info,
        .fill_link_info = bpf_nf_link_fill_link_info,