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| author | Florian Westphal <fw@strlen.de> | 2024-10-10 18:34:05 +0200 |
|---|---|---|
| committer | Pablo Neira Ayuso <pablo@netfilter.org> | 2024-10-17 13:58:57 +0200 |
| commit | 1230fe7ad3974f7bf6c78901473e039b34d4fb1f (patch) | |
| tree | 9dbc0104d2d74765838f5d5e6a6afc832ad09428 /net/netfilter | |
| parent | Merge branch 'mlx5-misc-fixes-2024-10-15' (diff) | |
| download | linux-1230fe7ad3974f7bf6c78901473e039b34d4fb1f.tar.xz linux-1230fe7ad3974f7bf6c78901473e039b34d4fb1f.zip | |
netfilter: bpf: must hold reference on net namespace
BUG: KASAN: slab-use-after-free in __nf_unregister_net_hook+0x640/0x6b0
Read of size 8 at addr ffff8880106fe400 by task repro/72=
bpf_nf_link_release+0xda/0x1e0
bpf_link_free+0x139/0x2d0
bpf_link_release+0x68/0x80
__fput+0x414/0xb60
Eric says:
It seems that bpf was able to defer the __nf_unregister_net_hook()
after exit()/close() time.
Perhaps a netns reference is missing, because the netns has been
dismantled/freed already.
bpf_nf_link_attach() does :
link->net = net;
But I do not see a reference being taken on net.
Add such a reference and release it after hook unreg.
Note that I was unable to get syzbot reproducer to work, so I
do not know if this resolves this splat.
Fixes: 84601d6ee68a ("bpf: add bpf_link support for BPF_NETFILTER programs")
Diagnosed-by: Eric Dumazet <edumazet@google.com>
Reported-by: Lai, Yi <yi1.lai@linux.intel.com>
Signed-off-by: Florian Westphal <fw@strlen.de>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Diffstat (limited to 'net/netfilter')
| -rw-r--r-- | net/netfilter/nf_bpf_link.c | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/net/netfilter/nf_bpf_link.c b/net/netfilter/nf_bpf_link.c index 5257d5e7eb09..e5e79a08c10b 100644 --- a/net/netfilter/nf_bpf_link.c +++ b/net/netfilter/nf_bpf_link.c @@ -23,6 +23,7 @@ static unsigned int nf_hook_run_bpf(void *bpf_prog, struct sk_buff *skb, struct bpf_nf_link { struct bpf_link link; struct nf_hook_ops hook_ops; + netns_tracker ns_tracker; struct net *net; u32 dead; const struct nf_defrag_hook *defrag_hook; @@ -120,6 +121,7 @@ static void bpf_nf_link_release(struct bpf_link *link) if (!cmpxchg(&nf_link->dead, 0, 1)) { nf_unregister_net_hook(nf_link->net, &nf_link->hook_ops); bpf_nf_disable_defrag(nf_link); + put_net_track(nf_link->net, &nf_link->ns_tracker); } } @@ -257,6 +259,8 @@ int bpf_nf_link_attach(const union bpf_attr *attr, struct bpf_prog *prog) return err; } + get_net_track(net, &link->ns_tracker, GFP_KERNEL); + return bpf_link_settle(&link_primer); } |