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, 234 insertions, 0 deletions

diff --git a/net/mac80211/s1g.c b/net/mac80211/s1g.c
new file mode 100644
index 000000000..bd7baf481
--- /dev/null
+++ b/net/mac80211/s1g.c
@@ -0,0 +1,234 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * S1G handling
+ * Copyright(c) 2020 Adapt-IP
+ * Copyright (C) 2023, 2026 Intel Corporation
+ */
+#include <linux/ieee80211.h>
+#include <net/mac80211.h>
+#include "ieee80211_i.h"
+#include "driver-ops.h"
+
+void ieee80211_s1g_sta_rate_init(struct sta_info *sta)
+{
+	/* avoid indicating legacy bitrates for S1G STAs */
+	sta->deflink.tx_stats.last_rate.flags |= IEEE80211_TX_RC_S1G_MCS;
+	sta->deflink.rx_stats.last_rate =
+			STA_STATS_FIELD(TYPE, STA_STATS_RATE_TYPE_S1G);
+}
+
+bool ieee80211_s1g_is_twt_setup(struct sk_buff *skb)
+{
+	struct ieee80211_mgmt *mgmt = (struct ieee80211_mgmt *)skb->data;
+
+	if (likely(!ieee80211_is_action(mgmt->frame_control)))
+		return false;
+
+	if (likely(mgmt->u.action.category != WLAN_CATEGORY_S1G))
+		return false;
+
+	return mgmt->u.action.action_code == WLAN_S1G_TWT_SETUP;
+}
+
+static void
+ieee80211_s1g_send_twt_setup(struct ieee80211_sub_if_data *sdata, const u8 *da,
+			     const u8 *bssid, struct ieee80211_twt_setup *twt)
+{
+	int len = IEEE80211_MIN_ACTION_SIZE(s1g) + 3 + twt->length;
+	struct ieee80211_local *local = sdata->local;
+	struct ieee80211_mgmt *mgmt;
+	struct sk_buff *skb;
+
+	skb = dev_alloc_skb(local->hw.extra_tx_headroom + len);
+	if (!skb)
+		return;
+
+	skb_reserve(skb, local->hw.extra_tx_headroom);
+	mgmt = skb_put_zero(skb, len);
+	mgmt->frame_control = cpu_to_le16(IEEE80211_FTYPE_MGMT |
+					  IEEE80211_STYPE_ACTION);
+	memcpy(mgmt->da, da, ETH_ALEN);
+	memcpy(mgmt->sa, sdata->vif.addr, ETH_ALEN);
+	memcpy(mgmt->bssid, bssid, ETH_ALEN);
+
+	mgmt->u.action.category = WLAN_CATEGORY_S1G;
+	mgmt->u.action.action_code = WLAN_S1G_TWT_SETUP;
+	memcpy(mgmt->u.action.s1g.variable, twt, 3 + twt->length);
+
+	IEEE80211_SKB_CB(skb)->flags |= IEEE80211_TX_INTFL_DONT_ENCRYPT |
+					IEEE80211_TX_INTFL_MLME_CONN_TX |
+					IEEE80211_TX_CTL_REQ_TX_STATUS;
+	ieee80211_tx_skb(sdata, skb);
+}
+
+static void
+ieee80211_s1g_send_twt_teardown(struct ieee80211_sub_if_data *sdata,
+				const u8 *da, const u8 *bssid, u8 flowid)
+{
+	struct ieee80211_local *local = sdata->local;
+	struct ieee80211_mgmt *mgmt;
+	struct sk_buff *skb;
+	u8 *id;
+
+	skb = dev_alloc_skb(local->hw.extra_tx_headroom +
+			    IEEE80211_MIN_ACTION_SIZE(s1g) + 1);
+	if (!skb)
+		return;
+
+	skb_reserve(skb, local->hw.extra_tx_headroom);
+	mgmt = skb_put_zero(skb, IEEE80211_MIN_ACTION_SIZE(s1g) + 1);
+	mgmt->frame_control = cpu_to_le16(IEEE80211_FTYPE_MGMT |
+					  IEEE80211_STYPE_ACTION);
+	memcpy(mgmt->da, da, ETH_ALEN);
+	memcpy(mgmt->sa, sdata->vif.addr, ETH_ALEN);
+	memcpy(mgmt->bssid, bssid, ETH_ALEN);
+
+	mgmt->u.action.category = WLAN_CATEGORY_S1G;
+	mgmt->u.action.action_code = WLAN_S1G_TWT_TEARDOWN;
+	id = (u8 *)mgmt->u.action.s1g.variable;
+	*id = flowid;
+
+	IEEE80211_SKB_CB(skb)->flags |= IEEE80211_TX_INTFL_DONT_ENCRYPT |
+					IEEE80211_TX_CTL_REQ_TX_STATUS;
+	ieee80211_tx_skb(sdata, skb);
+}
+
+static void
+ieee80211_s1g_rx_twt_setup(struct ieee80211_sub_if_data *sdata,
+			   struct sta_info *sta, struct sk_buff *skb)
+{
+	struct ieee80211_mgmt *mgmt = (void *)skb->data;
+	struct ieee80211_twt_setup *twt = (void *)mgmt->u.action.s1g.variable;
+	struct ieee80211_twt_params *twt_agrt = (void *)twt->params;
+
+	if (!(twt->control & IEEE80211_TWT_CONTROL_NEG_TYPE_BROADCAST) &&
+	    twt->length < sizeof(twt->control) + sizeof(*twt_agrt))
+		return;
+
+	twt_agrt->req_type &= cpu_to_le16(~IEEE80211_TWT_REQTYPE_REQUEST);
+
+	/* broadcast TWT not supported yet */
+	if (twt->control & IEEE80211_TWT_CONTROL_NEG_TYPE_BROADCAST) {
+		twt_agrt->req_type &=
+			~cpu_to_le16(IEEE80211_TWT_REQTYPE_SETUP_CMD);
+		twt_agrt->req_type |=
+			le16_encode_bits(TWT_SETUP_CMD_REJECT,
+					 IEEE80211_TWT_REQTYPE_SETUP_CMD);
+		goto out;
+	}
+
+	/* TWT Information not supported yet */
+	twt->control |= IEEE80211_TWT_CONTROL_RX_DISABLED;
+
+	drv_add_twt_setup(sdata->local, sdata, &sta->sta, twt);
+out:
+	ieee80211_s1g_send_twt_setup(sdata, mgmt->sa, sdata->vif.addr, twt);
+}
+
+static void
+ieee80211_s1g_rx_twt_teardown(struct ieee80211_sub_if_data *sdata,
+			      struct sta_info *sta, struct sk_buff *skb)
+{
+	struct ieee80211_mgmt *mgmt = (struct ieee80211_mgmt *)skb->data;
+
+	drv_twt_teardown_request(sdata->local, sdata, &sta->sta,
+				 mgmt->u.action.s1g.variable[0]);
+}
+
+static void
+ieee80211_s1g_tx_twt_setup_fail(struct ieee80211_sub_if_data *sdata,
+				struct sta_info *sta, struct sk_buff *skb)
+{
+	struct ieee80211_mgmt *mgmt = (struct ieee80211_mgmt *)skb->data;
+	struct ieee80211_twt_setup *twt = (void *)mgmt->u.action.s1g.variable;
+	struct ieee80211_twt_params *twt_agrt = (void *)twt->params;
+	u8 flowid = le16_get_bits(twt_agrt->req_type,
+				  IEEE80211_TWT_REQTYPE_FLOWID);
+
+	drv_twt_teardown_request(sdata->local, sdata, &sta->sta, flowid);
+
+	ieee80211_s1g_send_twt_teardown(sdata, mgmt->da, sdata->vif.addr,
+					flowid);
+}
+
+void ieee80211_s1g_rx_twt_action(struct ieee80211_sub_if_data *sdata,
+				 struct sk_buff *skb)
+{
+	struct ieee80211_mgmt *mgmt = (struct ieee80211_mgmt *)skb->data;
+	struct ieee80211_local *local = sdata->local;
+	struct sta_info *sta;
+
+	lockdep_assert_wiphy(local->hw.wiphy);
+
+	sta = sta_info_get_bss(sdata, mgmt->sa);
+	if (!sta)
+		return;
+
+	switch (mgmt->u.action.action_code) {
+	case WLAN_S1G_TWT_SETUP:
+		ieee80211_s1g_rx_twt_setup(sdata, sta, skb);
+		break;
+	case WLAN_S1G_TWT_TEARDOWN:
+		ieee80211_s1g_rx_twt_teardown(sdata, sta, skb);
+		break;
+	default:
+		break;
+	}
+}
+
+void ieee80211_s1g_status_twt_action(struct ieee80211_sub_if_data *sdata,
+				     struct sk_buff *skb)
+{
+	struct ieee80211_mgmt *mgmt = (struct ieee80211_mgmt *)skb->data;
+	struct ieee80211_local *local = sdata->local;
+	struct sta_info *sta;
+
+	lockdep_assert_wiphy(local->hw.wiphy);
+
+	sta = sta_info_get_bss(sdata, mgmt->da);
+	if (!sta)
+		return;
+
+	switch (mgmt->u.action.action_code) {
+	case WLAN_S1G_TWT_SETUP:
+		/* process failed twt setup frames */
+		ieee80211_s1g_tx_twt_setup_fail(sdata, sta, skb);
+		break;
+	default:
+		break;
+	}
+}
+
+void ieee80211_s1g_cap_to_sta_s1g_cap(struct ieee80211_sub_if_data *sdata,
+				      const struct ieee80211_s1g_cap *s1g_cap_ie,
+				      struct link_sta_info *link_sta)
+{
+	struct ieee80211_sta_s1g_cap *s1g_cap = &link_sta->pub->s1g_cap;
+
+	memset(s1g_cap, 0, sizeof(*s1g_cap));
+
+	memcpy(s1g_cap->cap, s1g_cap_ie->capab_info, sizeof(s1g_cap->cap));
+	memcpy(s1g_cap->nss_mcs, s1g_cap_ie->supp_mcs_nss,
+	       sizeof(s1g_cap->nss_mcs));
+
+	s1g_cap->s1g = true;
+
+	/* Maximum MPDU length is 1 bit for S1G */
+	if (s1g_cap->cap[3] & S1G_CAP3_MAX_MPDU_LEN) {
+		link_sta->pub->agg.max_amsdu_len =
+			IEEE80211_MAX_MPDU_LEN_VHT_7991;
+	} else {
+		link_sta->pub->agg.max_amsdu_len =
+			IEEE80211_MAX_MPDU_LEN_VHT_3895;
+	}
+
+	ieee80211_sta_recalc_aggregates(&link_sta->sta->sta);
+}
+
+bool ieee80211_s1g_use_ndp_ba(const struct ieee80211_sub_if_data *sdata,
+			      const struct sta_info *sta)
+{
+	return sdata->vif.cfg.s1g &&
+		ieee80211_hw_check(&sdata->local->hw, SUPPORTS_NDP_BLOCKACK) &&
+		(sta && sta->sta.deflink.s1g_cap.s1g);
+}