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, 422 insertions, 0 deletions

diff --git a/net/mac80211/debugfs_key.c b/net/mac80211/debugfs_key.c
new file mode 100644
index 000000000..117f58af5
--- /dev/null
+++ b/net/mac80211/debugfs_key.c
@@ -0,0 +1,422 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright 2003-2005	Devicescape Software, Inc.
+ * Copyright (c) 2006	Jiri Benc <jbenc@suse.cz>
+ * Copyright 2007	Johannes Berg <johannes@sipsolutions.net>
+ * Copyright (C) 2015	Intel Deutschland GmbH
+ * Copyright (C) 2021-2023   Intel Corporation
+ */
+
+#include <linux/kobject.h>
+#include <linux/slab.h>
+#include "ieee80211_i.h"
+#include "key.h"
+#include "debugfs.h"
+#include "debugfs_key.h"
+
+#define KEY_READ(name, prop, format_string)				\
+static ssize_t key_##name##_read(struct file *file,			\
+				 char __user *userbuf,			\
+				 size_t count, loff_t *ppos)		\
+{									\
+	struct ieee80211_key *key = file->private_data;			\
+	return mac80211_format_buffer(userbuf, count, ppos, 		\
+				      format_string, key->prop);	\
+}
+#define KEY_READ_X(name) KEY_READ(name, name, "0x%x\n")
+
+#define KEY_OPS(name)							\
+static const struct debugfs_short_fops key_ ##name## _ops = {		\
+	.read = key_##name##_read,					\
+	.llseek = generic_file_llseek,					\
+}
+
+#define KEY_OPS_W(name)							\
+static const struct debugfs_short_fops key_ ##name## _ops = {		\
+	.read = key_##name##_read,					\
+	.write = key_##name##_write,					\
+	.llseek = generic_file_llseek,					\
+}
+
+#define KEY_FILE(name, format)						\
+		 KEY_READ_##format(name)				\
+		 KEY_OPS(name)
+
+#define KEY_CONF_READ(name, format_string)				\
+	KEY_READ(conf_##name, conf.name, format_string)
+#define KEY_CONF_READ_D(name) KEY_CONF_READ(name, "%d\n")
+
+#define KEY_CONF_OPS(name)						\
+static const struct debugfs_short_fops key_ ##name## _ops = {		\
+	.read = key_conf_##name##_read,					\
+	.llseek = generic_file_llseek,					\
+}
+
+#define KEY_CONF_FILE(name, format)					\
+		 KEY_CONF_READ_##format(name)				\
+		 KEY_CONF_OPS(name)
+
+KEY_CONF_FILE(keylen, D);
+KEY_CONF_FILE(keyidx, D);
+KEY_CONF_FILE(hw_key_idx, D);
+KEY_FILE(flags, X);
+KEY_READ(ifindex, sdata->name, "%s\n");
+KEY_OPS(ifindex);
+
+static ssize_t key_algorithm_read(struct file *file,
+				  char __user *userbuf,
+				  size_t count, loff_t *ppos)
+{
+	char buf[15];
+	struct ieee80211_key *key = file->private_data;
+	u32 c = key->conf.cipher;
+
+	sprintf(buf, "%.2x-%.2x-%.2x:%d\n",
+		c >> 24, (c >> 16) & 0xff, (c >> 8) & 0xff, c & 0xff);
+	return simple_read_from_buffer(userbuf, count, ppos, buf, strlen(buf));
+}
+KEY_OPS(algorithm);
+
+static ssize_t key_tx_spec_write(struct file *file, const char __user *userbuf,
+				 size_t count, loff_t *ppos)
+{
+	struct ieee80211_key *key = file->private_data;
+	u64 pn;
+	int ret;
+
+	switch (key->conf.cipher) {
+	case WLAN_CIPHER_SUITE_WEP40:
+	case WLAN_CIPHER_SUITE_WEP104:
+		return -EINVAL;
+	case WLAN_CIPHER_SUITE_TKIP:
+		/* not supported yet */
+		return -EOPNOTSUPP;
+	case WLAN_CIPHER_SUITE_CCMP:
+	case WLAN_CIPHER_SUITE_CCMP_256:
+	case WLAN_CIPHER_SUITE_AES_CMAC:
+	case WLAN_CIPHER_SUITE_BIP_CMAC_256:
+	case WLAN_CIPHER_SUITE_BIP_GMAC_128:
+	case WLAN_CIPHER_SUITE_BIP_GMAC_256:
+	case WLAN_CIPHER_SUITE_GCMP:
+	case WLAN_CIPHER_SUITE_GCMP_256:
+		ret = kstrtou64_from_user(userbuf, count, 16, &pn);
+		if (ret)
+			return ret;
+		/* PN is a 48-bit counter */
+		if (pn >= (1ULL << 48))
+			return -ERANGE;
+		atomic64_set(&key->conf.tx_pn, pn);
+		return count;
+	default:
+		return 0;
+	}
+}
+
+static ssize_t key_tx_spec_read(struct file *file, char __user *userbuf,
+				size_t count, loff_t *ppos)
+{
+	u64 pn;
+	char buf[20];
+	int len;
+	struct ieee80211_key *key = file->private_data;
+
+	switch (key->conf.cipher) {
+	case WLAN_CIPHER_SUITE_WEP40:
+	case WLAN_CIPHER_SUITE_WEP104:
+		len = scnprintf(buf, sizeof(buf), "\n");
+		break;
+	case WLAN_CIPHER_SUITE_TKIP:
+		pn = atomic64_read(&key->conf.tx_pn);
+		len = scnprintf(buf, sizeof(buf), "%08x %04x\n",
+				TKIP_PN_TO_IV32(pn),
+				TKIP_PN_TO_IV16(pn));
+		break;
+	case WLAN_CIPHER_SUITE_CCMP:
+	case WLAN_CIPHER_SUITE_CCMP_256:
+	case WLAN_CIPHER_SUITE_AES_CMAC:
+	case WLAN_CIPHER_SUITE_BIP_CMAC_256:
+	case WLAN_CIPHER_SUITE_BIP_GMAC_128:
+	case WLAN_CIPHER_SUITE_BIP_GMAC_256:
+	case WLAN_CIPHER_SUITE_GCMP:
+	case WLAN_CIPHER_SUITE_GCMP_256:
+		pn = atomic64_read(&key->conf.tx_pn);
+		len = scnprintf(buf, sizeof(buf), "%02x%02x%02x%02x%02x%02x\n",
+				(u8)(pn >> 40), (u8)(pn >> 32), (u8)(pn >> 24),
+				(u8)(pn >> 16), (u8)(pn >> 8), (u8)pn);
+		break;
+	default:
+		return 0;
+	}
+	return simple_read_from_buffer(userbuf, count, ppos, buf, len);
+}
+KEY_OPS_W(tx_spec);
+
+static ssize_t key_rx_spec_read(struct file *file, char __user *userbuf,
+				size_t count, loff_t *ppos)
+{
+	struct ieee80211_key *key = file->private_data;
+	char buf[14*IEEE80211_NUM_TIDS+1], *p = buf;
+	int i, len;
+	const u8 *rpn;
+
+	switch (key->conf.cipher) {
+	case WLAN_CIPHER_SUITE_WEP40:
+	case WLAN_CIPHER_SUITE_WEP104:
+		len = scnprintf(buf, sizeof(buf), "\n");
+		break;
+	case WLAN_CIPHER_SUITE_TKIP:
+		for (i = 0; i < IEEE80211_NUM_TIDS; i++)
+			p += scnprintf(p, sizeof(buf)+buf-p,
+				       "%08x %04x\n",
+				       key->u.tkip.rx[i].iv32,
+				       key->u.tkip.rx[i].iv16);
+		len = p - buf;
+		break;
+	case WLAN_CIPHER_SUITE_CCMP:
+	case WLAN_CIPHER_SUITE_CCMP_256:
+		for (i = 0; i < IEEE80211_NUM_TIDS + 1; i++) {
+			rpn = key->u.ccmp.rx_pn[i];
+			p += scnprintf(p, sizeof(buf)+buf-p,
+				       "%02x%02x%02x%02x%02x%02x\n",
+				       rpn[0], rpn[1], rpn[2],
+				       rpn[3], rpn[4], rpn[5]);
+		}
+		len = p - buf;
+		break;
+	case WLAN_CIPHER_SUITE_AES_CMAC:
+	case WLAN_CIPHER_SUITE_BIP_CMAC_256:
+		rpn = key->u.aes_cmac.rx_pn;
+		p += scnprintf(p, sizeof(buf)+buf-p,
+			       "%02x%02x%02x%02x%02x%02x\n",
+			       rpn[0], rpn[1], rpn[2],
+			       rpn[3], rpn[4], rpn[5]);
+		len = p - buf;
+		break;
+	case WLAN_CIPHER_SUITE_BIP_GMAC_128:
+	case WLAN_CIPHER_SUITE_BIP_GMAC_256:
+		rpn = key->u.aes_gmac.rx_pn;
+		p += scnprintf(p, sizeof(buf)+buf-p,
+			       "%02x%02x%02x%02x%02x%02x\n",
+			       rpn[0], rpn[1], rpn[2],
+			       rpn[3], rpn[4], rpn[5]);
+		len = p - buf;
+		break;
+	case WLAN_CIPHER_SUITE_GCMP:
+	case WLAN_CIPHER_SUITE_GCMP_256:
+		for (i = 0; i < IEEE80211_NUM_TIDS + 1; i++) {
+			rpn = key->u.gcmp.rx_pn[i];
+			p += scnprintf(p, sizeof(buf)+buf-p,
+				       "%02x%02x%02x%02x%02x%02x\n",
+				       rpn[0], rpn[1], rpn[2],
+				       rpn[3], rpn[4], rpn[5]);
+		}
+		len = p - buf;
+		break;
+	default:
+		return 0;
+	}
+	return simple_read_from_buffer(userbuf, count, ppos, buf, len);
+}
+KEY_OPS(rx_spec);
+
+static ssize_t key_replays_read(struct file *file, char __user *userbuf,
+				size_t count, loff_t *ppos)
+{
+	struct ieee80211_key *key = file->private_data;
+	char buf[20];
+	int len;
+
+	switch (key->conf.cipher) {
+	case WLAN_CIPHER_SUITE_CCMP:
+	case WLAN_CIPHER_SUITE_CCMP_256:
+		len = scnprintf(buf, sizeof(buf), "%u\n", key->u.ccmp.replays);
+		break;
+	case WLAN_CIPHER_SUITE_AES_CMAC:
+	case WLAN_CIPHER_SUITE_BIP_CMAC_256:
+		len = scnprintf(buf, sizeof(buf), "%u\n",
+				key->u.aes_cmac.replays);
+		break;
+	case WLAN_CIPHER_SUITE_BIP_GMAC_128:
+	case WLAN_CIPHER_SUITE_BIP_GMAC_256:
+		len = scnprintf(buf, sizeof(buf), "%u\n",
+				key->u.aes_gmac.replays);
+		break;
+	case WLAN_CIPHER_SUITE_GCMP:
+	case WLAN_CIPHER_SUITE_GCMP_256:
+		len = scnprintf(buf, sizeof(buf), "%u\n", key->u.gcmp.replays);
+		break;
+	default:
+		return 0;
+	}
+	return simple_read_from_buffer(userbuf, count, ppos, buf, len);
+}
+KEY_OPS(replays);
+
+static ssize_t key_icverrors_read(struct file *file, char __user *userbuf,
+				  size_t count, loff_t *ppos)
+{
+	struct ieee80211_key *key = file->private_data;
+	char buf[20];
+	int len;
+
+	switch (key->conf.cipher) {
+	case WLAN_CIPHER_SUITE_AES_CMAC:
+	case WLAN_CIPHER_SUITE_BIP_CMAC_256:
+		len = scnprintf(buf, sizeof(buf), "%u\n",
+				key->u.aes_cmac.icverrors);
+		break;
+	case WLAN_CIPHER_SUITE_BIP_GMAC_128:
+	case WLAN_CIPHER_SUITE_BIP_GMAC_256:
+		len = scnprintf(buf, sizeof(buf), "%u\n",
+				key->u.aes_gmac.icverrors);
+		break;
+	default:
+		return 0;
+	}
+	return simple_read_from_buffer(userbuf, count, ppos, buf, len);
+}
+KEY_OPS(icverrors);
+
+static ssize_t key_mic_failures_read(struct file *file, char __user *userbuf,
+				     size_t count, loff_t *ppos)
+{
+	struct ieee80211_key *key = file->private_data;
+	char buf[20];
+	int len;
+
+	if (key->conf.cipher != WLAN_CIPHER_SUITE_TKIP)
+		return -EINVAL;
+
+	len = scnprintf(buf, sizeof(buf), "%u\n", key->u.tkip.mic_failures);
+
+	return simple_read_from_buffer(userbuf, count, ppos, buf, len);
+}
+KEY_OPS(mic_failures);
+
+static ssize_t key_key_read(struct file *file, char __user *userbuf,
+			    size_t count, loff_t *ppos)
+{
+	struct ieee80211_key *key = file->private_data;
+	int i, bufsize = 2 * key->conf.keylen + 2;
+	char *buf = kmalloc(bufsize, GFP_KERNEL);
+	char *p = buf;
+	ssize_t res;
+
+	if (!buf)
+		return -ENOMEM;
+
+	for (i = 0; i < key->conf.keylen; i++)
+		p += scnprintf(p, bufsize + buf - p, "%02x", key->conf.key[i]);
+	p += scnprintf(p, bufsize+buf-p, "\n");
+	res = simple_read_from_buffer(userbuf, count, ppos, buf, p - buf);
+	kfree(buf);
+	return res;
+}
+KEY_OPS(key);
+
+#define DEBUGFS_ADD(name) \
+	debugfs_create_file(#name, 0400, key->debugfs.dir, \
+			    key, &key_##name##_ops)
+#define DEBUGFS_ADD_W(name) \
+	debugfs_create_file(#name, 0600, key->debugfs.dir, \
+			    key, &key_##name##_ops);
+
+void ieee80211_debugfs_key_add(struct ieee80211_key *key)
+{
+	static int keycount;
+	char buf[100];
+	struct sta_info *sta;
+
+	if (!key->local->debugfs.keys)
+		return;
+
+	sprintf(buf, "%d", keycount);
+	key->debugfs.cnt = keycount;
+	keycount++;
+	key->debugfs.dir = debugfs_create_dir(buf,
+					key->local->debugfs.keys);
+
+	sta = key->sta;
+	if (sta) {
+		sprintf(buf, "../../netdev:%s/stations/%pM",
+			sta->sdata->name, sta->sta.addr);
+		key->debugfs.stalink =
+			debugfs_create_symlink("station", key->debugfs.dir, buf);
+	}
+
+	DEBUGFS_ADD(keylen);
+	DEBUGFS_ADD(flags);
+	DEBUGFS_ADD(keyidx);
+	DEBUGFS_ADD(hw_key_idx);
+	DEBUGFS_ADD(algorithm);
+	DEBUGFS_ADD_W(tx_spec);
+	DEBUGFS_ADD(rx_spec);
+	DEBUGFS_ADD(replays);
+	DEBUGFS_ADD(icverrors);
+	DEBUGFS_ADD(mic_failures);
+	DEBUGFS_ADD(key);
+	DEBUGFS_ADD(ifindex);
+};
+
+void ieee80211_debugfs_key_remove(struct ieee80211_key *key)
+{
+	if (!key)
+		return;
+
+	debugfs_remove_recursive(key->debugfs.dir);
+	key->debugfs.dir = NULL;
+}
+
+void ieee80211_debugfs_key_update_default(struct ieee80211_sub_if_data *sdata)
+{
+	char buf[50];
+	struct ieee80211_key *key;
+
+	if (!sdata->vif.debugfs_dir)
+		return;
+
+	lockdep_assert_wiphy(sdata->local->hw.wiphy);
+
+	debugfs_remove(sdata->debugfs.default_unicast_key);
+	sdata->debugfs.default_unicast_key = NULL;
+
+	if (sdata->default_unicast_key) {
+		key = wiphy_dereference(sdata->local->hw.wiphy,
+					sdata->default_unicast_key);
+		sprintf(buf, "../keys/%d", key->debugfs.cnt);
+		sdata->debugfs.default_unicast_key =
+			debugfs_create_symlink("default_unicast_key",
+					       sdata->vif.debugfs_dir, buf);
+	}
+
+	debugfs_remove(sdata->debugfs.default_multicast_key);
+	sdata->debugfs.default_multicast_key = NULL;
+
+	if (sdata->deflink.default_multicast_key) {
+		key = wiphy_dereference(sdata->local->hw.wiphy,
+					sdata->deflink.default_multicast_key);
+		sprintf(buf, "../keys/%d", key->debugfs.cnt);
+		sdata->debugfs.default_multicast_key =
+			debugfs_create_symlink("default_multicast_key",
+					       sdata->vif.debugfs_dir, buf);
+	}
+}
+
+void ieee80211_debugfs_key_remove_mgmt_default(struct ieee80211_sub_if_data *sdata)
+{
+	if (!sdata)
+		return;
+
+	debugfs_remove(sdata->debugfs.default_mgmt_key);
+	sdata->debugfs.default_mgmt_key = NULL;
+}
+
+void
+ieee80211_debugfs_key_remove_beacon_default(struct ieee80211_sub_if_data *sdata)
+{
+	if (!sdata)
+		return;
+
+	debugfs_remove(sdata->debugfs.default_beacon_key);
+	sdata->debugfs.default_beacon_key = NULL;
+}