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, 132 insertions, 0 deletions

diff --git a/net/wireless/nl80211.h b/net/wireless/nl80211.h
new file mode 100644
index 000000000..bdb065d14
--- /dev/null
+++ b/net/wireless/nl80211.h
@@ -0,0 +1,132 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Portions of this file
+ * Copyright (C) 2018, 2020-2026 Intel Corporation
+ */
+#ifndef __NET_WIRELESS_NL80211_H
+#define __NET_WIRELESS_NL80211_H
+
+#include "core.h"
+
+int nl80211_init(void);
+void nl80211_exit(void);
+
+void *nl80211hdr_put(struct sk_buff *skb, u32 portid, u32 seq,
+		     int flags, u8 cmd);
+bool nl80211_put_sta_rate(struct sk_buff *msg, struct rate_info *info,
+			  int attr);
+
+static inline u64 wdev_id(struct wireless_dev *wdev)
+{
+	return (u64)wdev->identifier |
+	       ((u64)wiphy_to_rdev(wdev->wiphy)->wiphy_idx << 32);
+}
+
+int nl80211_parse_chandef(struct cfg80211_registered_device *rdev,
+			  struct netlink_ext_ack *extack,
+			  struct nlattr **attrs,
+			  struct cfg80211_chan_def *chandef,
+			  bool npca_permitted);
+int nl80211_parse_random_mac(struct nlattr **attrs,
+			     u8 *mac_addr, u8 *mac_addr_mask);
+
+void nl80211_notify_wiphy(struct cfg80211_registered_device *rdev,
+			  enum nl80211_commands cmd);
+void nl80211_notify_iface(struct cfg80211_registered_device *rdev,
+			  struct wireless_dev *wdev,
+			  enum nl80211_commands cmd);
+void nl80211_send_scan_start(struct cfg80211_registered_device *rdev,
+			     struct wireless_dev *wdev);
+struct sk_buff *nl80211_build_scan_msg(struct cfg80211_registered_device *rdev,
+				       struct wireless_dev *wdev, bool aborted);
+void nl80211_send_scan_msg(struct cfg80211_registered_device *rdev,
+			   struct sk_buff *msg);
+void nl80211_send_sched_scan(struct cfg80211_sched_scan_request *req, u32 cmd);
+void nl80211_common_reg_change_event(enum nl80211_commands cmd_id,
+				     struct regulatory_request *request);
+
+static inline void
+nl80211_send_reg_change_event(struct regulatory_request *request)
+{
+	nl80211_common_reg_change_event(NL80211_CMD_REG_CHANGE, request);
+}
+
+static inline void
+nl80211_send_wiphy_reg_change_event(struct regulatory_request *request)
+{
+	nl80211_common_reg_change_event(NL80211_CMD_WIPHY_REG_CHANGE, request);
+}
+
+void nl80211_send_rx_auth(struct cfg80211_registered_device *rdev,
+			  struct net_device *netdev,
+			  const u8 *buf, size_t len, gfp_t gfp);
+void nl80211_send_rx_assoc(struct cfg80211_registered_device *rdev,
+			   struct net_device *netdev,
+			   const struct cfg80211_rx_assoc_resp_data *data);
+void nl80211_send_deauth(struct cfg80211_registered_device *rdev,
+			 struct net_device *netdev,
+			 const u8 *buf, size_t len,
+			 bool reconnect, gfp_t gfp);
+void nl80211_send_disassoc(struct cfg80211_registered_device *rdev,
+			   struct net_device *netdev,
+			   const u8 *buf, size_t len,
+			   bool reconnect, gfp_t gfp);
+void nl80211_send_auth_timeout(struct cfg80211_registered_device *rdev,
+			       struct net_device *netdev,
+			       const u8 *addr, gfp_t gfp);
+void nl80211_send_assoc_timeout(struct cfg80211_registered_device *rdev,
+				struct net_device *netdev,
+				const u8 *addr, gfp_t gfp);
+void nl80211_send_connect_result(struct cfg80211_registered_device *rdev,
+				 struct net_device *netdev,
+				 struct cfg80211_connect_resp_params *params,
+				 gfp_t gfp);
+void nl80211_send_roamed(struct cfg80211_registered_device *rdev,
+			 struct net_device *netdev,
+			 struct cfg80211_roam_info *info, gfp_t gfp);
+/* For STA/GC, indicate port authorized with AP/GO bssid.
+ * For GO/AP, use peer GC/STA mac_addr.
+ */
+void nl80211_send_port_authorized(struct cfg80211_registered_device *rdev,
+				  struct net_device *netdev, const u8 *peer_addr,
+				  const u8 *td_bitmap, u8 td_bitmap_len);
+void nl80211_send_disconnected(struct cfg80211_registered_device *rdev,
+			       struct net_device *netdev, u16 reason,
+			       const u8 *ie, size_t ie_len, bool from_ap);
+
+void
+nl80211_michael_mic_failure(struct cfg80211_registered_device *rdev,
+			    struct net_device *netdev, const u8 *addr,
+			    enum nl80211_key_type key_type,
+			    int key_id, const u8 *tsc, gfp_t gfp);
+
+void
+nl80211_send_beacon_hint_event(struct wiphy *wiphy,
+			       struct ieee80211_channel *channel_before,
+			       struct ieee80211_channel *channel_after);
+
+void nl80211_send_ibss_bssid(struct cfg80211_registered_device *rdev,
+			     struct net_device *netdev, const u8 *bssid,
+			     gfp_t gfp);
+
+int nl80211_send_mgmt(struct cfg80211_registered_device *rdev,
+		      struct wireless_dev *wdev, u32 nlpid,
+		      struct cfg80211_rx_info *info, gfp_t gfp);
+
+void
+nl80211_radar_notify(struct cfg80211_registered_device *rdev,
+		     const struct cfg80211_chan_def *chandef,
+		     enum nl80211_radar_event event,
+		     struct net_device *netdev, gfp_t gfp);
+
+void nl80211_send_ap_stopped(struct wireless_dev *wdev, unsigned int link_id);
+
+void cfg80211_free_coalesce(struct cfg80211_coalesce *coalesce);
+
+/* peer measurement */
+int nl80211_pmsr_start(struct sk_buff *skb, struct genl_info *info);
+
+void nl80211_mlo_reconf_add_done(struct net_device *dev,
+				 struct cfg80211_mlo_reconf_done_data *data);
+
+#endif /* __NET_WIRELESS_NL80211_H */