bpf: mark a NULL kfunc argument precisegrafted

check_kfunc_arg() allows bpf_register_is_null() for nullable arguments
w/o marking the underlying scalar register precise. Hence a checkpoint
created on such a path would prune against arbitrary scalar value.

Fixes: 3bda08b63670 ("bpf: Allow NULL buffers in bpf_dynptr_slice(_rw)")
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20260904-register-is-null-precise-fixes-v1-5-0f5a360ff15d@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

1 files changed, 48 insertions, 0 deletions

diff --git a/net/ipv6/exthdrs_offload.c b/net/ipv6/exthdrs_offload.c
new file mode 100644
index 000000000..4c00398f4
--- /dev/null
+++ b/net/ipv6/exthdrs_offload.c
@@ -0,0 +1,48 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *	IPV6 GSO/GRO offload support
+ *	Linux INET6 implementation
+ *
+ *      IPV6 Extension Header GSO/GRO support
+ */
+#include <net/protocol.h>
+#include "ip6_offload.h"
+
+static const struct net_offload rthdr_offload = {
+	.flags		=	INET6_PROTO_GSO_EXTHDR,
+};
+
+static const struct net_offload dstopt_offload = {
+	.flags		=	INET6_PROTO_GSO_EXTHDR,
+};
+
+static const struct net_offload hbh_offload = {
+	.flags		=	INET6_PROTO_GSO_EXTHDR,
+};
+
+int __init ipv6_exthdrs_offload_init(void)
+{
+	int ret;
+
+	ret = inet6_add_offload(&rthdr_offload, IPPROTO_ROUTING);
+	if (ret)
+		goto out;
+
+	ret = inet6_add_offload(&dstopt_offload, IPPROTO_DSTOPTS);
+	if (ret)
+		goto out_rt;
+
+	ret = inet6_add_offload(&hbh_offload, IPPROTO_HOPOPTS);
+	if (ret)
+		goto out_dstopts;
+
+out:
+	return ret;
+
+out_dstopts:
+	inet6_del_offload(&dstopt_offload, IPPROTO_DSTOPTS);
+
+out_rt:
+	inet6_del_offload(&rthdr_offload, IPPROTO_ROUTING);
+	goto out;
+}