From a5f7a5bb3b7f28ba7e4fa246775b29a0e5537255 Mon Sep 17 00:00:00 2001 From: Jinke Han Date: Tue, 8 Sep 2026 15:37:42 +0800 Subject: x86/kprobes: Fix crash when probing CS CALL instructions 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) Signed-off-by: Jinke Han Signed-off-by: Ingo Molnar Reviewed-by: Masami Hiramatsu (Google) Acked-by: Yafang Shao Acked-by: Borislav Petkov Cc: Peter Zijlstra Link: https://patch.msgid.link/20260908073742.GA10517@didi-ThinkCentre-M920t-N000 --- net/mac80211/ap.c | 353 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 353 insertions(+) create mode 100644 net/mac80211/ap.c (limited to 'net/mac80211/ap.c') diff --git a/net/mac80211/ap.c b/net/mac80211/ap.c new file mode 100644 index 000000000..e7ac99c5a --- /dev/null +++ b/net/mac80211/ap.c @@ -0,0 +1,353 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * AP handling + * + * Partially + * Copyright (C) 2026 Intel Corporation + */ + +#include "driver-ops.h" +#include "ieee80211_i.h" +#include "rate.h" + +static void +ieee80211_send_eml_op_mode_notif(struct ieee80211_sub_if_data *sdata, + struct ieee80211_mgmt *req, int opt_len) +{ + int len = IEEE80211_MIN_ACTION_SIZE(eml_omn); + struct ieee80211_local *local = sdata->local; + struct ieee80211_mgmt *mgmt; + struct sk_buff *skb; + + len += opt_len; /* optional len */ + skb = dev_alloc_skb(local->tx_headroom + len); + if (!skb) + return; + + skb_reserve(skb, local->tx_headroom); + mgmt = skb_put_zero(skb, len); + mgmt->frame_control = cpu_to_le16(IEEE80211_FTYPE_MGMT | + IEEE80211_STYPE_ACTION); + memcpy(mgmt->da, req->sa, ETH_ALEN); + memcpy(mgmt->sa, sdata->vif.addr, ETH_ALEN); + memcpy(mgmt->bssid, sdata->vif.addr, ETH_ALEN); + + mgmt->u.action.category = WLAN_CATEGORY_PROTECTED_EHT; + mgmt->u.action.action_code = + WLAN_PROTECTED_EHT_ACTION_EML_OP_MODE_NOTIF; + mgmt->u.action.eml_omn.dialog_token = + req->u.action.eml_omn.dialog_token; + mgmt->u.action.eml_omn.control = req->u.action.eml_omn.control & + ~(IEEE80211_EML_CTRL_EMLSR_PARAM_UPDATE | + IEEE80211_EML_CTRL_INDEV_COEX_ACT); + /* Copy optional fields from the received notification frame */ + memcpy(mgmt->u.action.eml_omn.variable, + req->u.action.eml_omn.variable, opt_len); + + ieee80211_tx_skb(sdata, skb); +} + +static void +ieee80211_rx_eml_op_mode_notif(struct ieee80211_sub_if_data *sdata, + struct sk_buff *skb) +{ + int len = IEEE80211_MIN_ACTION_SIZE(eml_omn); + enum nl80211_iftype type = ieee80211_vif_type_p2p(&sdata->vif); + struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(skb); + const struct wiphy_iftype_ext_capab *ift_ext_capa; + struct ieee80211_mgmt *mgmt = (void *)skb->data; + struct ieee80211_local *local = sdata->local; + u8 control = mgmt->u.action.eml_omn.control; + u8 *ptr = mgmt->u.action.eml_omn.variable; + struct ieee80211_eml_params eml_params = { + .link_id = status->link_id, + .control = control, + }; + struct sta_info *sta; + int opt_len = 0; + + if (!ieee80211_vif_is_mld(&sdata->vif)) + return; + + /* eMLSR and eMLMR can't be enabled at the same time */ + if ((control & IEEE80211_EML_CTRL_EMLSR_MODE) && + (control & IEEE80211_EML_CTRL_EMLMR_MODE)) + return; + + if ((control & IEEE80211_EML_CTRL_EMLMR_MODE) && + (control & IEEE80211_EML_CTRL_EMLSR_PARAM_UPDATE)) + return; + + ift_ext_capa = cfg80211_get_iftype_ext_capa(local->hw.wiphy, type); + if (!ift_ext_capa) + return; + + if (!status->link_valid) + return; + + sta = sta_info_get_bss(sdata, mgmt->sa); + if (!sta) + return; + + if (control & IEEE80211_EML_CTRL_EMLSR_MODE) { + u8 emlsr_param_update_len; + + if (!(ift_ext_capa->eml_capabilities & + IEEE80211_EML_CAP_EMLSR_SUPP)) + return; + + opt_len += sizeof(__le16); /* eMLSR link_bitmap */ + /* + * eMLSR param update field is not part of Notification frame + * sent by the AP to client so account it separately. + */ + emlsr_param_update_len = + !!(control & IEEE80211_EML_CTRL_EMLSR_PARAM_UPDATE); + + if (skb->len < len + opt_len + emlsr_param_update_len) + return; + + if (control & IEEE80211_EML_CTRL_EMLSR_PARAM_UPDATE) { + u8 pad_delay, trans_delay; + + pad_delay = u8_get_bits(ptr[2], + IEEE80211_EML_EMLSR_PAD_DELAY); + if (pad_delay > + IEEE80211_EML_CAP_EML_PADDING_DELAY_256US) + return; + + trans_delay = u8_get_bits(ptr[2], + IEEE80211_EML_EMLSR_TRANS_DELAY); + if (trans_delay > + IEEE80211_EML_CAP_EMLSR_TRANSITION_DELAY_256US) + return; + + /* Update sta padding and transition delay */ + sta->sta.eml_cap = + u8_replace_bits(sta->sta.eml_cap, + pad_delay, + IEEE80211_EML_CAP_EML_PADDING_DELAY); + sta->sta.eml_cap = + u8_replace_bits(sta->sta.eml_cap, + trans_delay, + IEEE80211_EML_CAP_EML_TRANSITION_DELAY); + } + } + + if (control & IEEE80211_EML_CTRL_EMLMR_MODE) { + u8 mcs_map_size; + int i; + + if (!(ift_ext_capa->eml_capabilities & + IEEE80211_EML_CAP_EMLMR_SUPPORT)) + return; + + opt_len += sizeof(__le16); /* eMLMR link_bitmap */ + opt_len++; /* eMLMR mcs_map_count */ + if (skb->len < len + opt_len) + return; + + eml_params.emlmr_mcs_map_count = ptr[2]; + if (eml_params.emlmr_mcs_map_count > 2) + return; + + mcs_map_size = 3 * (1 + eml_params.emlmr_mcs_map_count); + opt_len += mcs_map_size; + if (skb->len < len + opt_len) + return; + + for (i = 0; i < mcs_map_size; i++) { + u8 rx_mcs, tx_mcs; + + rx_mcs = u8_get_bits(ptr[3 + i], + IEEE80211_EML_EMLMR_RX_MCS_MAP); + if (rx_mcs > 8) + return; + + tx_mcs = u8_get_bits(ptr[3 + i], + IEEE80211_EML_EMLMR_TX_MCS_MAP); + if (tx_mcs > 8) + return; + } + + memcpy(eml_params.emlmr_mcs_map_bw, &ptr[3], mcs_map_size); + } + + if ((control & IEEE80211_EML_CTRL_EMLSR_MODE) || + (control & IEEE80211_EML_CTRL_EMLMR_MODE)) { + eml_params.link_bitmap = get_unaligned_le16(ptr); + if ((eml_params.link_bitmap & sdata->vif.active_links) != + eml_params.link_bitmap) + return; + } + + if (drv_set_eml_op_mode(sdata, &sta->sta, &eml_params)) + return; + + ieee80211_send_eml_op_mode_notif(sdata, mgmt, opt_len); +} + +static void +ieee80211_rx_uhr_link_reconfig_req(struct ieee80211_sub_if_data *sdata, + struct sk_buff *skb) +{ + struct ieee80211_mgmt *mgmt = (void *)skb->data; + const struct element *sub; + struct sta_info *sta; + + /* + * rx.c only accepts IEEE80211_UHR_LINK_RECONFIG_REQUEST_OMP_REQUEST + * which is valid, so no need to check the frame type/format/etc. + */ + + sta = sta_info_get_bss(sdata, mgmt->sa); + if (!sta) + return; + + struct ieee802_11_elems *elems __free(kfree) = + ieee802_11_parse_elems(mgmt->u.action.uhr_link_reconf_req.variable, + skb->len - IEEE80211_MIN_ACTION_SIZE(uhr_link_reconf_req), + IEEE80211_FTYPE_MGMT | IEEE80211_STYPE_ACTION, + NULL); + /* STA will assume we processed it, not good */ + if (!elems) + return; + + if (!elems->ml_reconf) + return; + + for_each_mle_subelement(sub, (u8 *)elems->ml_reconf, + elems->ml_reconf_len) { + const struct ieee80211_mle_per_sta_profile *prof = + (const void *)sub->data; + struct ieee80211_chanctx_conf *chanctx_conf; + struct ieee80211_chanctx *chanctx; + struct ieee80211_link_data *link; + struct link_sta_info *link_sta; + const struct element *chg; + u16 control; + u8 link_id; + + if (sub->id != IEEE80211_MLE_SUBELEM_PER_STA_PROFILE) + continue; + + if (!ieee80211_mle_reconf_sta_prof_size_ok(sub->data, + sub->datalen)) + return; + + control = le16_to_cpu(prof->control); + link_id = control & IEEE80211_MLE_STA_RECONF_CONTROL_LINK_ID; + + if (link_id >= IEEE80211_MLD_MAX_NUM_LINKS) + return; + + link = sdata_dereference(sdata->link[link_id], sdata); + if (!link) + continue; + + chanctx_conf = sdata_dereference(link->conf->chanctx_conf, + sdata); + if (!chanctx_conf) + continue; + chanctx = container_of(chanctx_conf, struct ieee80211_chanctx, + conf); + + link_sta = sdata_dereference(sta->link[link_id], sdata); + if (!link_sta) + continue; + + /* do we need to handle any other bits? */ + if (control & ~(IEEE80211_MLE_STA_RECONF_CONTROL_LINK_ID | + IEEE80211_MLE_STA_RECONF_CONTROL_OPERATION_TYPE)) + continue; + + if (u16_get_bits(control, IEEE80211_MLE_STA_RECONF_CONTROL_OPERATION_TYPE) != + IEEE80211_MLE_STA_RECONF_CONTROL_OPERATION_TYPE_UHR_OMP_UPD) + continue; + + for_each_element_extid(chg, WLAN_EID_EXT_UHR_MODE_CHG, + prof->variable + prof->sta_info_len - 1, + sub->datalen - sizeof(*prof) - + prof->sta_info_len + 1) { + const struct ieee80211_uhr_mode_change_tuple *tuple; + + for_each_uhr_mode_change_tuple(chg->data + 1, + chg->datalen - 1, + tuple) { + u8 id = le16_get_bits(tuple->control, + IEEE80211_UHR_MODE_CHANGE_CONTROL_MODE_ID); + bool enabled = le16_get_bits(tuple->control, + IEEE80211_UHR_MODE_CHANGE_CONTROL_MODE_ENABLE); + + /* only handle DBE (for now?) */ + if (id != IEEE80211_UHR_MODE_CHANGE_MODE_ID_DBE) + continue; + + link_sta->uhr_dbe_enabled = enabled; + /* also recalculates and updates per-STA bw */ + ieee80211_recalc_chanctx_min_def(sdata->local, + chanctx); + } + } + } + + /* TODO: send a response */ +} + +void ieee80211_ap_rx_queued_frame(struct ieee80211_sub_if_data *sdata, + struct sk_buff *skb) +{ + struct ieee80211_mgmt *mgmt = (void *)skb->data; + + /* rx.c cannot queue any non-action frames to AP interfaces */ + if (WARN_ON(!ieee80211_is_action(mgmt->frame_control))) + return; + + switch (mgmt->u.action.category) { + case WLAN_CATEGORY_PROTECTED_EHT: + switch (mgmt->u.action.action_code) { + case WLAN_PROTECTED_EHT_ACTION_EML_OP_MODE_NOTIF: + ieee80211_rx_eml_op_mode_notif(sdata, skb); + break; + } + break; + case WLAN_CATEGORY_PROTECTED_UHR: + switch (mgmt->u.action.action_code) { + case IEEE80211_PROTECTED_UHR_ACTION_LINK_RECONFIG_REQUEST: + ieee80211_rx_uhr_link_reconfig_req(sdata, skb); + break; + } + break; + } +} + +void ieee80211_uhr_disable_dbe_all_stas(struct ieee80211_link_data *link) +{ + struct ieee80211_sub_if_data *sdata = link->sdata; + struct ieee80211_local *local = sdata->local; + struct ieee80211_chanctx_conf *chanctx_conf; + struct ieee80211_chanctx *chanctx; + int link_id = link->link_id; + struct sta_info *sta; + + chanctx_conf = sdata_dereference(link->conf->chanctx_conf, sdata); + if (!chanctx_conf) + return; + chanctx = container_of(chanctx_conf, struct ieee80211_chanctx, conf); + + list_for_each_entry(sta, &local->sta_list, list) { + struct link_sta_info *link_sta; + + if (sta->sdata->bss != sdata->bss) + continue; + + link_sta = sdata_dereference(sta->link[link_id], sdata); + if (!link_sta) + continue; + + link_sta->uhr_dbe_enabled = false; + } + + /* also recalculates and updates per-STA bw */ + ieee80211_recalc_chanctx_min_def(local, chanctx); +} -- cgit v1.3.1