x86/kprobes: Fix crash when probing CS CALL instructionsgrafted

When using eBPF to probe CS CALL instructions within a function,
a crash can be triggered.

The eBPF tool probes offset 257 of the __hrtimer_run_queues()
function:

<__hrtimer_run_queues+249>:  nopl   0x0(%rax,%rax,1)
<__hrtimer_run_queues+254>:  mov    %r14,%rdi
<__hrtimer_run_queues+257>:  cs call <__x86_indirect_thunk_r12>
<__hrtimer_run_queues+263>:  mov    %eax,%r12d
<__hrtimer_run_queues+266>:  xchg   %ax,%ax
<__hrtimer_run_queues+268>:  mov    %r13,%rdi

Which triggers this crash:

  BUG: unable to handle page fault for address: 00000000000f41c9
  #PF: supervisor write access in kernel mode
  #PF: error_code(0x0002) - not-present page
  PGD 0 P4D 0
  Oops: 0002 [#1] SMP NOPTI
  CPU: 1 PID: 0 Comm: swapper/1 Kdump: loaded Tainted: P
  RIP: 0010:__hrtimer_run_queues+0x106/0x230

Note that __hrtimer_run_queues+0x106 is __hrtimer_run_queues+262, which is
at the 6th byte of the above CS CALL instruction. Since the CS CALL
instruction occupies 6 bytes, the exception occurred in the middle of that
call instruction.

The root cause is that when using eBPF tools to probe in the middle of a
function, a kprobe with INT3 is used as the underlying implementation.

During single-step emulation of the original CALL instruction,
int3_emulate_call() assumes that the probed CALL instruction is 5 bytes
long. However, the actual CS-prefixed CALL instruction occupies 6 bytes,
so it constructs an incorrect exception return address. When the CPU
returns from the kprobe handler, the next instruction to be executed is at
the address of the last byte of that CS CALL instruction. Coincidentally,
starting from that address, the CPU fetches and decodes a completely
different instruction, which ultimately triggers a kernel crash.

Fix the issue by using the actual instruction length obtained from
the instruction decoder when constructing the exception return
address, rather than relying on the hardcoded CALL_INSN_SIZE macro.

[ mingo: Refined the changelog ]

Fixes: 6256e668b7af ("x86/kprobes: Use int3 instead of debug trap for single-step")
Suggested-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Jinke Han <jinkehan@didiglobal.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Acked-by: Yafang Shao <laoar.shao@gmail.com>
Acked-by: Borislav Petkov <bp@alien8.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://patch.msgid.link/20260908073742.GA10517@didi-ThinkCentre-M920t-N000

1 files changed, 151 insertions, 0 deletions

diff --git a/net/nfc/nfc.h b/net/nfc/nfc.h
new file mode 100644
index 000000000..0b1e6466f
--- /dev/null
+++ b/net/nfc/nfc.h
@@ -0,0 +1,151 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Copyright (C) 2011 Instituto Nokia de Tecnologia
+ *
+ * Authors:
+ *    Lauro Ramos Venancio <lauro.venancio@openbossa.org>
+ *    Aloisio Almeida Jr <aloisio.almeida@openbossa.org>
+ */
+
+#ifndef __LOCAL_NFC_H
+#define __LOCAL_NFC_H
+
+#include <net/nfc/nfc.h>
+#include <net/sock.h>
+
+#define NFC_TARGET_MODE_IDLE 0
+#define NFC_TARGET_MODE_SLEEP 1
+
+struct nfc_protocol {
+	int id;
+	struct proto *proto;
+	struct module *owner;
+	int (*create)(struct net *net, struct socket *sock,
+		      const struct nfc_protocol *nfc_proto, int kern);
+};
+
+struct nfc_rawsock {
+	struct sock sk;
+	struct nfc_dev *dev;
+	u32 target_idx;
+	struct work_struct tx_work;
+	bool tx_work_scheduled;
+};
+
+struct nfc_sock_list {
+	struct hlist_head head;
+	rwlock_t          lock;
+};
+
+#define nfc_rawsock(sk) ((struct nfc_rawsock *) sk)
+#define to_rawsock_sk(_tx_work) \
+	((struct sock *) container_of(_tx_work, struct nfc_rawsock, tx_work))
+
+struct nfc_llcp_sdp_tlv;
+
+void nfc_llcp_mac_is_down(struct nfc_dev *dev);
+void nfc_llcp_mac_is_up(struct nfc_dev *dev, u32 target_idx,
+			u8 comm_mode, u8 rf_mode);
+int nfc_llcp_register_device(struct nfc_dev *dev);
+void nfc_llcp_unregister_device(struct nfc_dev *dev);
+int nfc_llcp_set_remote_gb(struct nfc_dev *dev, const u8 *gb, u8 gb_len);
+u8 *nfc_llcp_general_bytes(struct nfc_dev *dev, size_t *general_bytes_len);
+int nfc_llcp_data_received(struct nfc_dev *dev, struct sk_buff *skb);
+struct nfc_llcp_local *nfc_llcp_find_local(struct nfc_dev *dev);
+int nfc_llcp_local_put(struct nfc_llcp_local *local);
+int __init nfc_llcp_init(void);
+void nfc_llcp_exit(void);
+void nfc_llcp_free_sdp_tlv(struct nfc_llcp_sdp_tlv *sdp);
+void nfc_llcp_free_sdp_tlv_list(struct hlist_head *head);
+
+int __init rawsock_init(void);
+void rawsock_exit(void);
+
+int __init af_nfc_init(void);
+void af_nfc_exit(void);
+int nfc_proto_register(const struct nfc_protocol *nfc_proto);
+void nfc_proto_unregister(const struct nfc_protocol *nfc_proto);
+
+extern int nfc_devlist_generation;
+extern struct mutex nfc_devlist_mutex;
+
+int __init nfc_genl_init(void);
+void nfc_genl_exit(void);
+
+void nfc_genl_data_init(struct nfc_genl_data *genl_data);
+void nfc_genl_data_exit(struct nfc_genl_data *genl_data);
+
+int nfc_genl_targets_found(struct nfc_dev *dev);
+int nfc_genl_target_lost(struct nfc_dev *dev, u32 target_idx);
+
+int nfc_genl_device_added(struct nfc_dev *dev);
+int nfc_genl_device_removed(struct nfc_dev *dev);
+
+int nfc_genl_dep_link_up_event(struct nfc_dev *dev, u32 target_idx,
+			       u8 comm_mode, u8 rf_mode);
+int nfc_genl_dep_link_down_event(struct nfc_dev *dev);
+
+int nfc_genl_tm_activated(struct nfc_dev *dev, u32 protocol);
+int nfc_genl_tm_deactivated(struct nfc_dev *dev);
+
+int nfc_genl_llc_send_sdres(struct nfc_dev *dev, struct hlist_head *sdres_list);
+
+int nfc_genl_se_added(struct nfc_dev *dev, u32 se_idx, u16 type);
+int nfc_genl_se_removed(struct nfc_dev *dev, u32 se_idx);
+int nfc_genl_se_transaction(struct nfc_dev *dev, u8 se_idx,
+			    struct nfc_evt_transaction *evt_transaction);
+int nfc_genl_se_connectivity(struct nfc_dev *dev, u8 se_idx);
+
+struct nfc_dev *nfc_get_device(unsigned int idx);
+
+static inline void nfc_put_device(struct nfc_dev *dev)
+{
+	put_device(&dev->dev);
+}
+
+static inline void nfc_device_iter_init(struct class_dev_iter *iter)
+{
+	class_dev_iter_init(iter, &nfc_class, NULL, NULL);
+}
+
+static inline struct nfc_dev *nfc_device_iter_next(struct class_dev_iter *iter)
+{
+	struct device *d = class_dev_iter_next(iter);
+	if (!d)
+		return NULL;
+
+	return to_nfc_dev(d);
+}
+
+static inline void nfc_device_iter_exit(struct class_dev_iter *iter)
+{
+	class_dev_iter_exit(iter);
+}
+
+int nfc_fw_download(struct nfc_dev *dev, const char *firmware_name);
+int nfc_genl_fw_download_done(struct nfc_dev *dev, const char *firmware_name,
+			      u32 result);
+
+int nfc_dev_up(struct nfc_dev *dev);
+
+int nfc_dev_down(struct nfc_dev *dev);
+
+int nfc_start_poll(struct nfc_dev *dev, u32 im_protocols, u32 tm_protocols);
+
+int nfc_stop_poll(struct nfc_dev *dev);
+
+int nfc_dep_link_up(struct nfc_dev *dev, int target_idx, u8 comm_mode);
+
+int nfc_dep_link_down(struct nfc_dev *dev);
+
+int nfc_activate_target(struct nfc_dev *dev, u32 target_idx, u32 protocol);
+
+int nfc_deactivate_target(struct nfc_dev *dev, u32 target_idx, u8 mode);
+
+int nfc_data_exchange(struct nfc_dev *dev, u32 target_idx, struct sk_buff *skb,
+		      data_exchange_cb_t cb, void *cb_context);
+
+int nfc_enable_se(struct nfc_dev *dev, u32 se_idx);
+int nfc_disable_se(struct nfc_dev *dev, u32 se_idx);
+
+#endif /* __LOCAL_NFC_H */