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, 75 insertions, 0 deletions

diff --git a/net/atm/raw.c b/net/atm/raw.c
new file mode 100644
index 000000000..87d136c75
--- /dev/null
+++ b/net/atm/raw.c
@@ -0,0 +1,75 @@
+// SPDX-License-Identifier: GPL-2.0
+/* net/atm/raw.c - Raw AAL0 and AAL5 transports */
+
+/* Written 1995-2000 by Werner Almesberger, EPFL LRC/ICA */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ":%s: " fmt, __func__
+
+#include <linux/module.h>
+#include <linux/atmdev.h>
+#include <linux/capability.h>
+#include <linux/kernel.h>
+#include <linux/skbuff.h>
+#include <linux/mm.h>
+#include <linux/slab.h>
+
+#include "common.h"
+#include "protocols.h"
+
+/*
+ * SKB == NULL indicates that the link is being closed
+ */
+
+static void atm_push_raw(struct atm_vcc *vcc, struct sk_buff *skb)
+{
+	if (skb) {
+		struct sock *sk = sk_atm(vcc);
+
+		skb_queue_tail(&sk->sk_receive_queue, skb);
+		sk->sk_data_ready(sk);
+	}
+}
+
+static void atm_pop_raw(struct atm_vcc *vcc, struct sk_buff *skb)
+{
+	struct sock *sk = sk_atm(vcc);
+
+	pr_debug("(%d) %d -= %d\n",
+		 vcc->vci, sk_wmem_alloc_get(sk), ATM_SKB(skb)->acct_truesize);
+	atm_return_tx(vcc, skb);
+	dev_kfree_skb_any(skb);
+	sk->sk_write_space(sk);
+}
+
+static int atm_send_aal0(struct atm_vcc *vcc, struct sk_buff *skb)
+{
+	/*
+	 * Note that if vpi/vci are _ANY or _UNSPEC the below will
+	 * still work
+	 */
+	if (!capable(CAP_NET_ADMIN) &&
+	    (((u32 *)skb->data)[0] & (ATM_HDR_VPI_MASK | ATM_HDR_VCI_MASK)) !=
+	    ((vcc->vpi << ATM_HDR_VPI_SHIFT) |
+	     (vcc->vci << ATM_HDR_VCI_SHIFT))) {
+		kfree_skb(skb);
+		return -EADDRNOTAVAIL;
+	}
+	return vcc->dev->ops->send(vcc, skb);
+}
+
+int atm_init_aal0(struct atm_vcc *vcc)
+{
+	vcc->push = atm_push_raw;
+	vcc->pop = atm_pop_raw;
+	vcc->send = atm_send_aal0;
+	return 0;
+}
+
+int atm_init_aal5(struct atm_vcc *vcc)
+{
+	vcc->push = atm_push_raw;
+	vcc->pop = atm_pop_raw;
+	vcc->send = vcc->dev->ops->send;
+	return 0;
+}
+EXPORT_SYMBOL(atm_init_aal5);