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, 377 insertions, 0 deletions

diff --git a/net/mac80211/led.c b/net/mac80211/led.c
new file mode 100644
index 000000000..b5600d223
--- /dev/null
+++ b/net/mac80211/led.c
@@ -0,0 +1,377 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright 2006, Johannes Berg <johannes@sipsolutions.net>
+ */
+
+/* just for IFNAMSIZ */
+#include <linux/if.h>
+#include <linux/slab.h>
+#include <linux/export.h>
+#include "led.h"
+
+void ieee80211_led_assoc(struct ieee80211_local *local, bool associated)
+{
+	if (!atomic_read(&local->assoc_led_active))
+		return;
+	if (associated)
+		led_trigger_event(&local->assoc_led, LED_FULL);
+	else
+		led_trigger_event(&local->assoc_led, LED_OFF);
+}
+
+void ieee80211_led_radio(struct ieee80211_local *local, bool enabled)
+{
+	if (!atomic_read(&local->radio_led_active))
+		return;
+	if (enabled)
+		led_trigger_event(&local->radio_led, LED_FULL);
+	else
+		led_trigger_event(&local->radio_led, LED_OFF);
+}
+
+void ieee80211_alloc_led_names(struct ieee80211_local *local)
+{
+	local->rx_led.name = kasprintf(GFP_KERNEL, "%srx",
+				       wiphy_name(local->hw.wiphy));
+	local->tx_led.name = kasprintf(GFP_KERNEL, "%stx",
+				       wiphy_name(local->hw.wiphy));
+	local->assoc_led.name = kasprintf(GFP_KERNEL, "%sassoc",
+					  wiphy_name(local->hw.wiphy));
+	local->radio_led.name = kasprintf(GFP_KERNEL, "%sradio",
+					  wiphy_name(local->hw.wiphy));
+}
+
+void ieee80211_free_led_names(struct ieee80211_local *local)
+{
+	kfree(local->rx_led.name);
+	kfree(local->tx_led.name);
+	kfree(local->assoc_led.name);
+	kfree(local->radio_led.name);
+}
+
+static int ieee80211_tx_led_activate(struct led_classdev *led_cdev)
+{
+	struct ieee80211_local *local = container_of(led_cdev->trigger,
+						     struct ieee80211_local,
+						     tx_led);
+
+	atomic_inc(&local->tx_led_active);
+
+	return 0;
+}
+
+static void ieee80211_tx_led_deactivate(struct led_classdev *led_cdev)
+{
+	struct ieee80211_local *local = container_of(led_cdev->trigger,
+						     struct ieee80211_local,
+						     tx_led);
+
+	atomic_dec(&local->tx_led_active);
+}
+
+static int ieee80211_rx_led_activate(struct led_classdev *led_cdev)
+{
+	struct ieee80211_local *local = container_of(led_cdev->trigger,
+						     struct ieee80211_local,
+						     rx_led);
+
+	atomic_inc(&local->rx_led_active);
+
+	return 0;
+}
+
+static void ieee80211_rx_led_deactivate(struct led_classdev *led_cdev)
+{
+	struct ieee80211_local *local = container_of(led_cdev->trigger,
+						     struct ieee80211_local,
+						     rx_led);
+
+	atomic_dec(&local->rx_led_active);
+}
+
+static int ieee80211_assoc_led_activate(struct led_classdev *led_cdev)
+{
+	struct ieee80211_local *local = container_of(led_cdev->trigger,
+						     struct ieee80211_local,
+						     assoc_led);
+
+	atomic_inc(&local->assoc_led_active);
+
+	return 0;
+}
+
+static void ieee80211_assoc_led_deactivate(struct led_classdev *led_cdev)
+{
+	struct ieee80211_local *local = container_of(led_cdev->trigger,
+						     struct ieee80211_local,
+						     assoc_led);
+
+	atomic_dec(&local->assoc_led_active);
+}
+
+static int ieee80211_radio_led_activate(struct led_classdev *led_cdev)
+{
+	struct ieee80211_local *local = container_of(led_cdev->trigger,
+						     struct ieee80211_local,
+						     radio_led);
+
+	atomic_inc(&local->radio_led_active);
+
+	return 0;
+}
+
+static void ieee80211_radio_led_deactivate(struct led_classdev *led_cdev)
+{
+	struct ieee80211_local *local = container_of(led_cdev->trigger,
+						     struct ieee80211_local,
+						     radio_led);
+
+	atomic_dec(&local->radio_led_active);
+}
+
+static int ieee80211_tpt_led_activate(struct led_classdev *led_cdev)
+{
+	struct ieee80211_local *local = container_of(led_cdev->trigger,
+						     struct ieee80211_local,
+						     tpt_led);
+
+	atomic_inc(&local->tpt_led_active);
+
+	return 0;
+}
+
+static void ieee80211_tpt_led_deactivate(struct led_classdev *led_cdev)
+{
+	struct ieee80211_local *local = container_of(led_cdev->trigger,
+						     struct ieee80211_local,
+						     tpt_led);
+
+	atomic_dec(&local->tpt_led_active);
+}
+
+void ieee80211_led_init(struct ieee80211_local *local)
+{
+	atomic_set(&local->rx_led_active, 0);
+	local->rx_led.activate = ieee80211_rx_led_activate;
+	local->rx_led.deactivate = ieee80211_rx_led_deactivate;
+	if (local->rx_led.name && led_trigger_register(&local->rx_led)) {
+		kfree(local->rx_led.name);
+		local->rx_led.name = NULL;
+	}
+
+	atomic_set(&local->tx_led_active, 0);
+	local->tx_led.activate = ieee80211_tx_led_activate;
+	local->tx_led.deactivate = ieee80211_tx_led_deactivate;
+	if (local->tx_led.name && led_trigger_register(&local->tx_led)) {
+		kfree(local->tx_led.name);
+		local->tx_led.name = NULL;
+	}
+
+	atomic_set(&local->assoc_led_active, 0);
+	local->assoc_led.activate = ieee80211_assoc_led_activate;
+	local->assoc_led.deactivate = ieee80211_assoc_led_deactivate;
+	if (local->assoc_led.name && led_trigger_register(&local->assoc_led)) {
+		kfree(local->assoc_led.name);
+		local->assoc_led.name = NULL;
+	}
+
+	atomic_set(&local->radio_led_active, 0);
+	local->radio_led.activate = ieee80211_radio_led_activate;
+	local->radio_led.deactivate = ieee80211_radio_led_deactivate;
+	if (local->radio_led.name && led_trigger_register(&local->radio_led)) {
+		kfree(local->radio_led.name);
+		local->radio_led.name = NULL;
+	}
+
+	atomic_set(&local->tpt_led_active, 0);
+	if (local->tpt_led_trigger) {
+		local->tpt_led.activate = ieee80211_tpt_led_activate;
+		local->tpt_led.deactivate = ieee80211_tpt_led_deactivate;
+		if (led_trigger_register(&local->tpt_led)) {
+			kfree(local->tpt_led_trigger);
+			local->tpt_led_trigger = NULL;
+		}
+	}
+}
+
+void ieee80211_led_exit(struct ieee80211_local *local)
+{
+	if (local->radio_led.name)
+		led_trigger_unregister(&local->radio_led);
+	if (local->assoc_led.name)
+		led_trigger_unregister(&local->assoc_led);
+	if (local->tx_led.name)
+		led_trigger_unregister(&local->tx_led);
+	if (local->rx_led.name)
+		led_trigger_unregister(&local->rx_led);
+
+	if (local->tpt_led_trigger) {
+		led_trigger_unregister(&local->tpt_led);
+		kfree(local->tpt_led_trigger);
+	}
+}
+
+const char *__ieee80211_get_radio_led_name(struct ieee80211_hw *hw)
+{
+	struct ieee80211_local *local = hw_to_local(hw);
+
+	return local->radio_led.name;
+}
+EXPORT_SYMBOL(__ieee80211_get_radio_led_name);
+
+const char *__ieee80211_get_assoc_led_name(struct ieee80211_hw *hw)
+{
+	struct ieee80211_local *local = hw_to_local(hw);
+
+	return local->assoc_led.name;
+}
+EXPORT_SYMBOL(__ieee80211_get_assoc_led_name);
+
+const char *__ieee80211_get_tx_led_name(struct ieee80211_hw *hw)
+{
+	struct ieee80211_local *local = hw_to_local(hw);
+
+	return local->tx_led.name;
+}
+EXPORT_SYMBOL(__ieee80211_get_tx_led_name);
+
+const char *__ieee80211_get_rx_led_name(struct ieee80211_hw *hw)
+{
+	struct ieee80211_local *local = hw_to_local(hw);
+
+	return local->rx_led.name;
+}
+EXPORT_SYMBOL(__ieee80211_get_rx_led_name);
+
+static unsigned long tpt_trig_traffic(struct ieee80211_local *local,
+				      struct tpt_led_trigger *tpt_trig)
+{
+	unsigned long traffic, delta;
+
+	traffic = tpt_trig->tx_bytes + tpt_trig->rx_bytes;
+
+	delta = traffic - tpt_trig->prev_traffic;
+	tpt_trig->prev_traffic = traffic;
+	return DIV_ROUND_UP(delta, 1024 / 8);
+}
+
+static void tpt_trig_timer(struct timer_list *t)
+{
+	struct tpt_led_trigger *tpt_trig = timer_container_of(tpt_trig, t,
+							      timer);
+	struct ieee80211_local *local = tpt_trig->local;
+	unsigned long on, off, tpt;
+	int i;
+
+	if (!tpt_trig->running)
+		return;
+
+	mod_timer(&tpt_trig->timer, round_jiffies(jiffies + HZ));
+
+	tpt = tpt_trig_traffic(local, tpt_trig);
+
+	/* default to just solid on */
+	on = 1;
+	off = 0;
+
+	for (i = tpt_trig->blink_table_len - 1; i >= 0; i--) {
+		if (tpt_trig->blink_table[i].throughput < 0 ||
+		    tpt > tpt_trig->blink_table[i].throughput) {
+			off = tpt_trig->blink_table[i].blink_time / 2;
+			on = tpt_trig->blink_table[i].blink_time - off;
+			break;
+		}
+	}
+
+	led_trigger_blink(&local->tpt_led, on, off);
+}
+
+const char *
+__ieee80211_create_tpt_led_trigger(struct ieee80211_hw *hw,
+				   unsigned int flags,
+				   const struct ieee80211_tpt_blink *blink_table,
+				   unsigned int blink_table_len)
+{
+	struct ieee80211_local *local = hw_to_local(hw);
+	struct tpt_led_trigger *tpt_trig;
+
+	if (WARN_ON(local->tpt_led_trigger))
+		return NULL;
+
+	tpt_trig = kzalloc_obj(struct tpt_led_trigger);
+	if (!tpt_trig)
+		return NULL;
+
+	snprintf(tpt_trig->name, sizeof(tpt_trig->name),
+		 "%stpt", wiphy_name(local->hw.wiphy));
+
+	local->tpt_led.name = tpt_trig->name;
+
+	tpt_trig->blink_table = blink_table;
+	tpt_trig->blink_table_len = blink_table_len;
+	tpt_trig->want = flags;
+	tpt_trig->local = local;
+
+	timer_setup(&tpt_trig->timer, tpt_trig_timer, 0);
+
+	local->tpt_led_trigger = tpt_trig;
+
+	return tpt_trig->name;
+}
+EXPORT_SYMBOL(__ieee80211_create_tpt_led_trigger);
+
+static void ieee80211_start_tpt_led_trig(struct ieee80211_local *local)
+{
+	struct tpt_led_trigger *tpt_trig = local->tpt_led_trigger;
+
+	if (tpt_trig->running)
+		return;
+
+	/* reset traffic */
+	tpt_trig_traffic(local, tpt_trig);
+	tpt_trig->running = true;
+
+	tpt_trig_timer(&tpt_trig->timer);
+	mod_timer(&tpt_trig->timer, round_jiffies(jiffies + HZ));
+}
+
+static void ieee80211_stop_tpt_led_trig(struct ieee80211_local *local)
+{
+	struct tpt_led_trigger *tpt_trig = local->tpt_led_trigger;
+
+	if (!tpt_trig->running)
+		return;
+
+	tpt_trig->running = false;
+	timer_delete_sync(&tpt_trig->timer);
+
+	led_trigger_event(&local->tpt_led, LED_OFF);
+}
+
+void ieee80211_mod_tpt_led_trig(struct ieee80211_local *local,
+				unsigned int types_on, unsigned int types_off)
+{
+	struct tpt_led_trigger *tpt_trig = local->tpt_led_trigger;
+	bool allowed;
+
+	WARN_ON(types_on & types_off);
+
+	if (!tpt_trig)
+		return;
+
+	tpt_trig->active &= ~types_off;
+	tpt_trig->active |= types_on;
+
+	/*
+	 * Regardless of wanted state, we shouldn't blink when
+	 * the radio is disabled -- this can happen due to some
+	 * code ordering issues with __ieee80211_recalc_idle()
+	 * being called before the radio is started.
+	 */
+	allowed = tpt_trig->active & IEEE80211_TPT_LEDTRIG_FL_RADIO;
+
+	if (!allowed || !(tpt_trig->active & tpt_trig->want))
+		ieee80211_stop_tpt_led_trig(local);
+	else
+		ieee80211_start_tpt_led_trig(local);
+}