The conntrack lookup and allocation kfuncs take an opts pointer together with an opts__sz argument. The verifier checks only the memory range described by opts__sz, but the wrappers unconditionally write opts->error whenever the internal lookup or allocation helper returns an error. For an invalid size smaller than the end of opts->error, that write can land outside the verifier-checked range. Keep returning NULL for invalid arguments, but only report the error through opts->error when the supplied size includes the field. This preserves error reporting for the supported 12-byte and 16-byte layouts, and for other invalid sizes that still include opts->error. Fixes: b4c2b9593a1c ("net/netfilter: Add unstable CT lookup helpers for XDP and TC-BPF") Fixes: d7e79c97c00c ("net: netfilter: Add kfuncs to allocate and insert CT") Signed-off-by: Yiyang Chen --- net/netfilter/nf_conntrack_bpf.c | 17 +++++++++++++---- 1 file changed, 13 insertions(+), 4 deletions(-) diff --git a/net/netfilter/nf_conntrack_bpf.c b/net/netfilter/nf_conntrack_bpf.c index 40c261cd0af38..3c182024ec509 100644 --- a/net/netfilter/nf_conntrack_bpf.c +++ b/net/netfilter/nf_conntrack_bpf.c @@ -65,6 +65,11 @@ enum { NF_BPF_CT_OPTS_SZ = 16, }; +static bool bpf_ct_opts_has_error(u32 opts_len) +{ + return opts_len >= offsetofend(struct bpf_ct_opts, error); +} + static int bpf_nf_ct_tuple_parse(struct bpf_sock_tuple *bpf_tuple, u32 tuple_len, u8 protonum, u8 dir, struct nf_conntrack_tuple *tuple) @@ -298,7 +303,8 @@ bpf_xdp_ct_alloc(struct xdp_md *xdp_ctx, struct bpf_sock_tuple *bpf_tuple, nfct = __bpf_nf_ct_alloc_entry(dev_net(ctx->rxq->dev), bpf_tuple, tuple__sz, opts, opts__sz, 10); if (IS_ERR(nfct)) { - opts->error = PTR_ERR(nfct); + if (bpf_ct_opts_has_error(opts__sz)) + opts->error = PTR_ERR(nfct); return NULL; } @@ -332,7 +338,8 @@ bpf_xdp_ct_lookup(struct xdp_md *xdp_ctx, struct bpf_sock_tuple *bpf_tuple, caller_net = dev_net(ctx->rxq->dev); nfct = __bpf_nf_ct_lookup(caller_net, bpf_tuple, tuple__sz, opts, opts__sz); if (IS_ERR(nfct)) { - opts->error = PTR_ERR(nfct); + if (bpf_ct_opts_has_error(opts__sz)) + opts->error = PTR_ERR(nfct); return NULL; } return nfct; @@ -364,7 +371,8 @@ bpf_skb_ct_alloc(struct __sk_buff *skb_ctx, struct bpf_sock_tuple *bpf_tuple, net = skb->dev ? dev_net(skb->dev) : sock_net(skb->sk); nfct = __bpf_nf_ct_alloc_entry(net, bpf_tuple, tuple__sz, opts, opts__sz, 10); if (IS_ERR(nfct)) { - opts->error = PTR_ERR(nfct); + if (bpf_ct_opts_has_error(opts__sz)) + opts->error = PTR_ERR(nfct); return NULL; } @@ -398,7 +406,8 @@ bpf_skb_ct_lookup(struct __sk_buff *skb_ctx, struct bpf_sock_tuple *bpf_tuple, caller_net = skb->dev ? dev_net(skb->dev) : sock_net(skb->sk); nfct = __bpf_nf_ct_lookup(caller_net, bpf_tuple, tuple__sz, opts, opts__sz); if (IS_ERR(nfct)) { - opts->error = PTR_ERR(nfct); + if (bpf_ct_opts_has_error(opts__sz)) + opts->error = PTR_ERR(nfct); return NULL; } return nfct; -- 2.34.1