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, 249 insertions, 0 deletions

diff --git a/net/mac80211/debug.h b/net/mac80211/debug.h
new file mode 100644
index 000000000..ef7c1a68d
--- /dev/null
+++ b/net/mac80211/debug.h
@@ -0,0 +1,249 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Portions
+ * Copyright (C) 2022 - 2025 Intel Corporation
+ */
+#ifndef __MAC80211_DEBUG_H
+#define __MAC80211_DEBUG_H
+#include <linux/once_lite.h>
+#include <net/cfg80211.h>
+
+#ifdef CONFIG_MAC80211_OCB_DEBUG
+#define MAC80211_OCB_DEBUG 1
+#else
+#define MAC80211_OCB_DEBUG 0
+#endif
+
+#ifdef CONFIG_MAC80211_IBSS_DEBUG
+#define MAC80211_IBSS_DEBUG 1
+#else
+#define MAC80211_IBSS_DEBUG 0
+#endif
+
+#ifdef CONFIG_MAC80211_PS_DEBUG
+#define MAC80211_PS_DEBUG 1
+#else
+#define MAC80211_PS_DEBUG 0
+#endif
+
+#ifdef CONFIG_MAC80211_HT_DEBUG
+#define MAC80211_HT_DEBUG 1
+#else
+#define MAC80211_HT_DEBUG 0
+#endif
+
+#ifdef CONFIG_MAC80211_MPL_DEBUG
+#define MAC80211_MPL_DEBUG 1
+#else
+#define MAC80211_MPL_DEBUG 0
+#endif
+
+#ifdef CONFIG_MAC80211_MPATH_DEBUG
+#define MAC80211_MPATH_DEBUG 1
+#else
+#define MAC80211_MPATH_DEBUG 0
+#endif
+
+#ifdef CONFIG_MAC80211_MHWMP_DEBUG
+#define MAC80211_MHWMP_DEBUG 1
+#else
+#define MAC80211_MHWMP_DEBUG 0
+#endif
+
+#ifdef CONFIG_MAC80211_MESH_SYNC_DEBUG
+#define MAC80211_MESH_SYNC_DEBUG 1
+#else
+#define MAC80211_MESH_SYNC_DEBUG 0
+#endif
+
+#ifdef CONFIG_MAC80211_MESH_CSA_DEBUG
+#define MAC80211_MESH_CSA_DEBUG 1
+#else
+#define MAC80211_MESH_CSA_DEBUG 0
+#endif
+
+#ifdef CONFIG_MAC80211_MESH_PS_DEBUG
+#define MAC80211_MESH_PS_DEBUG 1
+#else
+#define MAC80211_MESH_PS_DEBUG 0
+#endif
+
+#ifdef CONFIG_MAC80211_TDLS_DEBUG
+#define MAC80211_TDLS_DEBUG 1
+#else
+#define MAC80211_TDLS_DEBUG 0
+#endif
+
+#ifdef CONFIG_MAC80211_STA_DEBUG
+#define MAC80211_STA_DEBUG 1
+#else
+#define MAC80211_STA_DEBUG 0
+#endif
+
+#ifdef CONFIG_MAC80211_MLME_DEBUG
+#define MAC80211_MLME_DEBUG 1
+#else
+#define MAC80211_MLME_DEBUG 0
+#endif
+
+#ifdef CONFIG_MAC80211_MESSAGE_TRACING
+void __sdata_info(const char *fmt, ...) __printf(1, 2);
+void __sdata_dbg(bool print, const char *fmt, ...) __printf(2, 3);
+void __sdata_err(const char *fmt, ...) __printf(1, 2);
+void __wiphy_dbg(struct wiphy *wiphy, bool print, const char *fmt, ...)
+	__printf(3, 4);
+
+#define _sdata_info(sdata, fmt, ...)					\
+	__sdata_info("%s: " fmt, (sdata)->name, ##__VA_ARGS__)
+#define _sdata_dbg(print, sdata, fmt, ...)				\
+	__sdata_dbg(print, "%s: " fmt, (sdata)->name, ##__VA_ARGS__)
+#define _sdata_err(sdata, fmt, ...)					\
+	__sdata_err("%s: " fmt, (sdata)->name, ##__VA_ARGS__)
+#define _wiphy_dbg(print, wiphy, fmt, ...)				\
+	__wiphy_dbg(wiphy, print, fmt, ##__VA_ARGS__)
+#else
+#define _sdata_info(sdata, fmt, ...)					\
+do {									\
+	pr_info("%s: " fmt,						\
+		(sdata)->name, ##__VA_ARGS__);				\
+} while (0)
+
+#define _sdata_dbg(print, sdata, fmt, ...)				\
+do {									\
+	if (print)							\
+		pr_debug("%s: " fmt,					\
+			 (sdata)->name, ##__VA_ARGS__);			\
+} while (0)
+
+#define _sdata_err(sdata, fmt, ...)					\
+do {									\
+	pr_err("%s: " fmt,						\
+	       (sdata)->name, ##__VA_ARGS__);				\
+} while (0)
+
+#define _wiphy_dbg(print, wiphy, fmt, ...)				\
+do {									\
+	if (print)							\
+		wiphy_dbg((wiphy), fmt, ##__VA_ARGS__);			\
+} while (0)
+#endif
+
+#define sdata_info(sdata, fmt, ...)					\
+	_sdata_info(sdata, fmt, ##__VA_ARGS__)
+#define sdata_err(sdata, fmt, ...)					\
+	_sdata_err(sdata, fmt, ##__VA_ARGS__)
+#define sdata_dbg(sdata, fmt, ...)					\
+	_sdata_dbg(1, sdata, fmt, ##__VA_ARGS__)
+
+#define link_info(link, fmt, ...)					\
+	do {								\
+		if (ieee80211_vif_is_mld(&(link)->sdata->vif))          \
+			_sdata_info((link)->sdata, "[link %d] " fmt,	\
+				    (link)->link_id,			\
+				    ##__VA_ARGS__);			\
+		else							\
+			_sdata_info((link)->sdata, fmt, ##__VA_ARGS__);	\
+	} while (0)
+#define link_err(link, fmt, ...)					\
+	do {								\
+		if (ieee80211_vif_is_mld(&(link)->sdata->vif))          \
+			_sdata_err((link)->sdata, "[link %d] " fmt,	\
+				   (link)->link_id,			\
+				   ##__VA_ARGS__);			\
+		else							\
+			_sdata_err((link)->sdata, fmt, ##__VA_ARGS__);	\
+	} while (0)
+#define link_err_once(link, fmt, ...)					\
+	DO_ONCE_LITE(link_err, link, fmt, ##__VA_ARGS__)
+#define link_id_info(sdata, link_id, fmt, ...)				\
+	do {								\
+		if (ieee80211_vif_is_mld(&sdata->vif))			\
+			_sdata_info(sdata, "[link %d] " fmt, link_id,	\
+				    ##__VA_ARGS__);			\
+		else							\
+			_sdata_info(sdata, fmt, ##__VA_ARGS__);		\
+	} while (0)
+#define _link_id_dbg(print, sdata, link_id, fmt, ...)			\
+	do {								\
+		if (ieee80211_vif_is_mld(&(sdata)->vif))		\
+			_sdata_dbg(print, sdata, "[link %d] " fmt,	\
+				   link_id, ##__VA_ARGS__);		\
+		else							\
+			_sdata_dbg(print, sdata, fmt, ##__VA_ARGS__);	\
+	} while (0)
+#define link_dbg(link, fmt, ...)					\
+	_link_id_dbg(1, (link)->sdata, (link)->link_id,			\
+		     fmt, ##__VA_ARGS__)
+
+#define ht_dbg(sdata, fmt, ...)						\
+	_sdata_dbg(MAC80211_HT_DEBUG,					\
+		   sdata, fmt, ##__VA_ARGS__)
+
+#define ht_dbg_ratelimited(sdata, fmt, ...)				\
+	_sdata_dbg(MAC80211_HT_DEBUG && net_ratelimit(),		\
+		   sdata, fmt, ##__VA_ARGS__)
+
+#define ocb_dbg(sdata, fmt, ...)					\
+	_sdata_dbg(MAC80211_OCB_DEBUG,					\
+		   sdata, fmt, ##__VA_ARGS__)
+
+#define ibss_dbg(sdata, fmt, ...)					\
+	_sdata_dbg(MAC80211_IBSS_DEBUG,					\
+		   sdata, fmt, ##__VA_ARGS__)
+
+#define ps_dbg(sdata, fmt, ...)						\
+	_sdata_dbg(MAC80211_PS_DEBUG,					\
+		   sdata, fmt, ##__VA_ARGS__)
+
+#define ps_dbg_hw(hw, fmt, ...)						\
+	_wiphy_dbg(MAC80211_PS_DEBUG,					\
+		   (hw)->wiphy, fmt, ##__VA_ARGS__)
+
+#define ps_dbg_ratelimited(sdata, fmt, ...)				\
+	_sdata_dbg(MAC80211_PS_DEBUG && net_ratelimit(),		\
+		   sdata, fmt, ##__VA_ARGS__)
+
+#define mpl_dbg(sdata, fmt, ...)					\
+	_sdata_dbg(MAC80211_MPL_DEBUG,					\
+		   sdata, fmt, ##__VA_ARGS__)
+
+#define mpath_dbg(sdata, fmt, ...)					\
+	_sdata_dbg(MAC80211_MPATH_DEBUG,				\
+		   sdata, fmt, ##__VA_ARGS__)
+
+#define mhwmp_dbg(sdata, fmt, ...)					\
+	_sdata_dbg(MAC80211_MHWMP_DEBUG,				\
+		   sdata, fmt, ##__VA_ARGS__)
+
+#define msync_dbg(sdata, fmt, ...)					\
+	_sdata_dbg(MAC80211_MESH_SYNC_DEBUG,				\
+		   sdata, fmt, ##__VA_ARGS__)
+
+#define mcsa_dbg(sdata, fmt, ...)					\
+	_sdata_dbg(MAC80211_MESH_CSA_DEBUG,				\
+		   sdata, fmt, ##__VA_ARGS__)
+
+#define mps_dbg(sdata, fmt, ...)					\
+	_sdata_dbg(MAC80211_MESH_PS_DEBUG,				\
+		   sdata, fmt, ##__VA_ARGS__)
+
+#define tdls_dbg(sdata, fmt, ...)					\
+	_sdata_dbg(MAC80211_TDLS_DEBUG,					\
+		   sdata, fmt, ##__VA_ARGS__)
+
+#define sta_dbg(sdata, fmt, ...)					\
+	_sdata_dbg(MAC80211_STA_DEBUG,					\
+		   sdata, fmt, ##__VA_ARGS__)
+
+#define mlme_dbg(sdata, fmt, ...)					\
+	_sdata_dbg(MAC80211_MLME_DEBUG,					\
+		   sdata, fmt, ##__VA_ARGS__)
+#define mlme_link_id_dbg(sdata, link_id, fmt, ...)			\
+	_link_id_dbg(MAC80211_MLME_DEBUG, sdata, link_id,		\
+		     fmt, ##__VA_ARGS__)
+
+#define mlme_dbg_ratelimited(sdata, fmt, ...)				\
+	_sdata_dbg(MAC80211_MLME_DEBUG && net_ratelimit(),		\
+		   sdata, fmt, ##__VA_ARGS__)
+
+#endif /* __MAC80211_DEBUG_H */