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, 428 insertions, 0 deletions

diff --git a/drivers/media/dvb-frontends/sp2.c b/drivers/media/dvb-frontends/sp2.c
new file mode 100644
index 000000000..63dec4b4f
--- /dev/null
+++ b/drivers/media/dvb-frontends/sp2.c
@@ -0,0 +1,428 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * CIMaX SP2/SP2HF (Atmel T90FJR) CI driver
+ *
+ * Copyright (C) 2014 Olli Salonen <olli.salonen@iki.fi>
+ *
+ * Heavily based on CIMax2(R) SP2 driver in conjunction with NetUp Dual
+ * DVB-S2 CI card (cimax2) with following copyrights:
+ *
+ *  Copyright (C) 2009 NetUP Inc.
+ *  Copyright (C) 2009 Igor M. Liplianin <liplianin@netup.ru>
+ *  Copyright (C) 2009 Abylay Ospan <aospan@netup.ru>
+ */
+
+#include "sp2_priv.h"
+
+static int sp2_read_i2c(struct sp2 *s, u8 reg, u8 *buf, int len)
+{
+	int ret;
+	struct i2c_client *client = s->client;
+	struct i2c_adapter *adap = client->adapter;
+	struct i2c_msg msg[] = {
+		{
+			.addr = client->addr,
+			.flags = 0,
+			.buf = &reg,
+			.len = 1
+		}, {
+			.addr = client->addr,
+			.flags	= I2C_M_RD,
+			.buf = buf,
+			.len = len
+		}
+	};
+
+	ret = i2c_transfer(adap, msg, 2);
+
+	if (ret != 2) {
+		dev_err(&client->dev, "i2c read error, reg = 0x%02x, status = %d\n",
+				reg, ret);
+		if (ret < 0)
+			return ret;
+		else
+			return -EIO;
+	}
+
+	dev_dbg(&s->client->dev, "addr=0x%04x, reg = 0x%02x, data = %02x\n",
+				client->addr, reg, buf[0]);
+
+	return 0;
+}
+
+static int sp2_write_i2c(struct sp2 *s, u8 reg, u8 *buf, int len)
+{
+	int ret;
+	u8 buffer[35];
+	struct i2c_client *client = s->client;
+	struct i2c_adapter *adap = client->adapter;
+	struct i2c_msg msg = {
+		.addr = client->addr,
+		.flags = 0,
+		.buf = &buffer[0],
+		.len = len + 1
+	};
+
+	if ((len + 1) > sizeof(buffer)) {
+		dev_err(&client->dev, "i2c wr reg=%02x: len=%d is too big!\n",
+				reg, len);
+		return -EINVAL;
+	}
+
+	buffer[0] = reg;
+	memcpy(&buffer[1], buf, len);
+
+	ret = i2c_transfer(adap, &msg, 1);
+
+	if (ret != 1) {
+		dev_err(&client->dev, "i2c write error, reg = 0x%02x, status = %d\n",
+				reg, ret);
+		if (ret < 0)
+			return ret;
+		else
+			return -EIO;
+	}
+
+	dev_dbg(&s->client->dev, "addr=0x%04x, reg = 0x%02x, data = %*ph\n",
+				client->addr, reg, len, buf);
+
+	return 0;
+}
+
+static int sp2_ci_op_cam(struct dvb_ca_en50221 *en50221, int slot, u8 acs,
+			u8 read, int addr, u8 data)
+{
+	struct sp2 *s = en50221->data;
+	u8 store;
+	int mem, ret;
+	int (*ci_op_cam)(void*, u8, int, u8, int*) = s->ci_control;
+
+	if (slot != 0)
+		return -EINVAL;
+
+	/*
+	 * change module access type between IO space and attribute memory
+	 * when needed
+	 */
+	if (s->module_access_type != acs) {
+		ret = sp2_read_i2c(s, 0x00, &store, 1);
+
+		if (ret)
+			return ret;
+
+		store &= ~(SP2_MOD_CTL_ACS1 | SP2_MOD_CTL_ACS0);
+		store |= acs;
+
+		ret = sp2_write_i2c(s, 0x00, &store, 1);
+		if (ret)
+			return ret;
+	}
+
+	s->module_access_type = acs;
+
+	/* implementation of ci_op_cam is device specific */
+	if (ci_op_cam) {
+		ret = ci_op_cam(s->priv, read, addr, data, &mem);
+	} else {
+		dev_err(&s->client->dev, "callback not defined");
+		return -EINVAL;
+	}
+
+	if (ret)
+		return ret;
+
+	dev_dbg(&s->client->dev, "%s: slot=%d, addr=0x%04x, %s, data=%x",
+			(read) ? "read" : "write", slot, addr,
+			(acs == SP2_CI_ATTR_ACS) ? "attr" : "io",
+			(read) ? mem : data);
+
+	if (read)
+		return mem;
+	else
+		return 0;
+
+}
+
+int sp2_ci_read_attribute_mem(struct dvb_ca_en50221 *en50221,
+				int slot, int addr)
+{
+	return sp2_ci_op_cam(en50221, slot, SP2_CI_ATTR_ACS,
+			SP2_CI_RD, addr, 0);
+}
+
+int sp2_ci_write_attribute_mem(struct dvb_ca_en50221 *en50221,
+				int slot, int addr, u8 data)
+{
+	return sp2_ci_op_cam(en50221, slot, SP2_CI_ATTR_ACS,
+			SP2_CI_WR, addr, data);
+}
+
+int sp2_ci_read_cam_control(struct dvb_ca_en50221 *en50221,
+				int slot, u8 addr)
+{
+	return sp2_ci_op_cam(en50221, slot, SP2_CI_IO_ACS,
+			SP2_CI_RD, addr, 0);
+}
+
+int sp2_ci_write_cam_control(struct dvb_ca_en50221 *en50221,
+				int slot, u8 addr, u8 data)
+{
+	return sp2_ci_op_cam(en50221, slot, SP2_CI_IO_ACS,
+			SP2_CI_WR, addr, data);
+}
+
+int sp2_ci_slot_reset(struct dvb_ca_en50221 *en50221, int slot)
+{
+	struct sp2 *s = en50221->data;
+	u8 buf;
+	int ret;
+
+	dev_dbg(&s->client->dev, "slot: %d\n", slot);
+
+	if (slot != 0)
+		return -EINVAL;
+
+	/* RST on */
+	buf = SP2_MOD_CTL_RST;
+	ret = sp2_write_i2c(s, 0x00, &buf, 1);
+
+	if (ret)
+		return ret;
+
+	usleep_range(500, 600);
+
+	/* RST off */
+	buf = 0x00;
+	ret = sp2_write_i2c(s, 0x00, &buf, 1);
+
+	if (ret)
+		return ret;
+
+	msleep(1000);
+
+	return 0;
+}
+
+int sp2_ci_slot_shutdown(struct dvb_ca_en50221 *en50221, int slot)
+{
+	struct sp2 *s = en50221->data;
+
+	dev_dbg(&s->client->dev, "slot:%d\n", slot);
+
+	/* not implemented */
+	return 0;
+}
+
+int sp2_ci_slot_ts_enable(struct dvb_ca_en50221 *en50221, int slot)
+{
+	struct sp2 *s = en50221->data;
+	u8 buf;
+
+	dev_dbg(&s->client->dev, "slot:%d\n", slot);
+
+	if (slot != 0)
+		return -EINVAL;
+
+	sp2_read_i2c(s, 0x00, &buf, 1);
+
+	/* disable bypass and enable TS */
+	buf |= (SP2_MOD_CTL_TSOEN | SP2_MOD_CTL_TSIEN);
+	return sp2_write_i2c(s, 0, &buf, 1);
+}
+
+int sp2_ci_poll_slot_status(struct dvb_ca_en50221 *en50221,
+				int slot, int open)
+{
+	struct sp2 *s = en50221->data;
+	u8 buf[2];
+	int ret;
+
+	dev_dbg(&s->client->dev, "slot:%d open:%d\n", slot, open);
+
+	/*
+	 * CAM module INSERT/REMOVE processing. Slow operation because of i2c
+	 * transfers. Throttle read to one per sec.
+	 */
+	if (time_after(jiffies, s->next_status_checked_time)) {
+		ret = sp2_read_i2c(s, 0x00, buf, 1);
+		s->next_status_checked_time = jiffies +	msecs_to_jiffies(1000);
+
+		if (ret)
+			return 0;
+
+		if (buf[0] & SP2_MOD_CTL_DET)
+			s->status = DVB_CA_EN50221_POLL_CAM_PRESENT |
+					DVB_CA_EN50221_POLL_CAM_READY;
+		else
+			s->status = 0;
+	}
+
+	return s->status;
+}
+
+static int sp2_init(struct sp2 *s)
+{
+	int ret = 0;
+	u8 buf;
+	u8 cimax_init[34] = {
+		0x00, /* module A control*/
+		0x00, /* auto select mask high A */
+		0x00, /* auto select mask low A */
+		0x00, /* auto select pattern high A */
+		0x00, /* auto select pattern low A */
+		0x44, /* memory access time A, 600 ns */
+		0x00, /* invert input A */
+		0x00, /* RFU */
+		0x00, /* RFU */
+		0x00, /* module B control*/
+		0x00, /* auto select mask high B */
+		0x00, /* auto select mask low B */
+		0x00, /* auto select pattern high B */
+		0x00, /* auto select pattern low B */
+		0x44, /* memory access time B, 600 ns */
+		0x00, /* invert input B */
+		0x00, /* RFU */
+		0x00, /* RFU */
+		0x00, /* auto select mask high Ext */
+		0x00, /* auto select mask low Ext */
+		0x00, /* auto select pattern high Ext */
+		0x00, /* auto select pattern low Ext */
+		0x00, /* RFU */
+		0x02, /* destination - module A */
+		0x01, /* power control reg, VCC power on */
+		0x00, /* RFU */
+		0x00, /* int status read only */
+		0x00, /* Interrupt Mask Register */
+		0x05, /* EXTINT=active-high, INT=push-pull */
+		0x00, /* USCG1 */
+		0x04, /* ack active low */
+		0x00, /* LOCK = 0 */
+		0x22, /* unknown */
+		0x00, /* synchronization? */
+	};
+
+	dev_dbg(&s->client->dev, "\n");
+
+	s->ca.owner = THIS_MODULE;
+	s->ca.read_attribute_mem = sp2_ci_read_attribute_mem;
+	s->ca.write_attribute_mem = sp2_ci_write_attribute_mem;
+	s->ca.read_cam_control = sp2_ci_read_cam_control;
+	s->ca.write_cam_control = sp2_ci_write_cam_control;
+	s->ca.slot_reset = sp2_ci_slot_reset;
+	s->ca.slot_shutdown = sp2_ci_slot_shutdown;
+	s->ca.slot_ts_enable = sp2_ci_slot_ts_enable;
+	s->ca.poll_slot_status = sp2_ci_poll_slot_status;
+	s->ca.data = s;
+	s->module_access_type = 0;
+
+	/* initialize all regs */
+	ret = sp2_write_i2c(s, 0x00, &cimax_init[0], 34);
+	if (ret)
+		goto err;
+
+	/* lock registers */
+	buf = 1;
+	ret = sp2_write_i2c(s, 0x1f, &buf, 1);
+	if (ret)
+		goto err;
+
+	/* power on slots */
+	ret = sp2_write_i2c(s, 0x18, &buf, 1);
+	if (ret)
+		goto err;
+
+	ret = dvb_ca_en50221_init(s->dvb_adap, &s->ca, 0, 1);
+	if (ret)
+		goto err;
+
+	return 0;
+
+err:
+	dev_dbg(&s->client->dev, "init failed=%d\n", ret);
+	return ret;
+}
+
+static int sp2_exit(struct i2c_client *client)
+{
+	struct sp2 *s;
+
+	dev_dbg(&client->dev, "\n");
+
+	if (!client)
+		return 0;
+
+	s = i2c_get_clientdata(client);
+	if (!s)
+		return 0;
+
+	if (!s->ca.data)
+		return 0;
+
+	dvb_ca_en50221_release(&s->ca);
+
+	return 0;
+}
+
+static int sp2_probe(struct i2c_client *client)
+{
+	struct sp2_config *cfg = client->dev.platform_data;
+	struct sp2 *s;
+	int ret;
+
+	dev_dbg(&client->dev, "\n");
+
+	s = kzalloc_obj(*s);
+	if (!s) {
+		ret = -ENOMEM;
+		goto err;
+	}
+
+	s->client = client;
+	s->dvb_adap = cfg->dvb_adap;
+	s->priv = cfg->priv;
+	s->ci_control = cfg->ci_control;
+
+	i2c_set_clientdata(client, s);
+
+	ret = sp2_init(s);
+	if (ret)
+		goto err;
+
+	dev_info(&s->client->dev, "CIMaX SP2 successfully attached\n");
+	return 0;
+err:
+	dev_dbg(&client->dev, "init failed=%d\n", ret);
+	kfree(s);
+
+	return ret;
+}
+
+static void sp2_remove(struct i2c_client *client)
+{
+	struct sp2 *s = i2c_get_clientdata(client);
+
+	dev_dbg(&client->dev, "\n");
+	sp2_exit(client);
+	kfree(s);
+}
+
+static const struct i2c_device_id sp2_id[] = {
+	{ .name = "sp2" },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, sp2_id);
+
+static struct i2c_driver sp2_driver = {
+	.driver = {
+		.name	= "sp2",
+	},
+	.probe		= sp2_probe,
+	.remove		= sp2_remove,
+	.id_table	= sp2_id,
+};
+
+module_i2c_driver(sp2_driver);
+
+MODULE_DESCRIPTION("CIMaX SP2/HF CI driver");
+MODULE_AUTHOR("Olli Salonen <olli.salonen@iki.fi>");
+MODULE_LICENSE("GPL");