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, 136 insertions, 0 deletions

diff --git a/drivers/reset/reset-pistachio.c b/drivers/reset/reset-pistachio.c
new file mode 100644
index 000000000..151ceeb42
--- /dev/null
+++ b/drivers/reset/reset-pistachio.c
@@ -0,0 +1,136 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Pistachio SoC Reset Controller driver
+ *
+ * Copyright (C) 2015 Imagination Technologies Ltd.
+ *
+ * Author: Damien Horsley <Damien.Horsley@imgtec.com>
+ */
+
+#include <linux/init.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+#include <linux/reset-controller.h>
+#include <linux/slab.h>
+#include <linux/mfd/syscon.h>
+
+#include <dt-bindings/reset/pistachio-resets.h>
+
+#define	PISTACHIO_SOFT_RESET		0
+
+struct pistachio_reset_data {
+	struct reset_controller_dev	rcdev;
+	struct regmap			*periph_regs;
+};
+
+static inline int pistachio_reset_shift(unsigned long id)
+{
+	switch (id) {
+	case PISTACHIO_RESET_I2C0:
+	case PISTACHIO_RESET_I2C1:
+	case PISTACHIO_RESET_I2C2:
+	case PISTACHIO_RESET_I2C3:
+	case PISTACHIO_RESET_I2S_IN:
+	case PISTACHIO_RESET_PRL_OUT:
+	case PISTACHIO_RESET_SPDIF_OUT:
+	case PISTACHIO_RESET_SPI:
+	case PISTACHIO_RESET_PWM_PDM:
+	case PISTACHIO_RESET_UART0:
+	case PISTACHIO_RESET_UART1:
+	case PISTACHIO_RESET_QSPI:
+	case PISTACHIO_RESET_MDC:
+	case PISTACHIO_RESET_SDHOST:
+	case PISTACHIO_RESET_ETHERNET:
+	case PISTACHIO_RESET_IR:
+	case PISTACHIO_RESET_HASH:
+	case PISTACHIO_RESET_TIMER:
+		return id;
+	case PISTACHIO_RESET_I2S_OUT:
+	case PISTACHIO_RESET_SPDIF_IN:
+	case PISTACHIO_RESET_EVT:
+		return id + 6;
+	case PISTACHIO_RESET_USB_H:
+	case PISTACHIO_RESET_USB_PR:
+	case PISTACHIO_RESET_USB_PHY_PR:
+	case PISTACHIO_RESET_USB_PHY_PON:
+		return id + 7;
+	default:
+		return -EINVAL;
+	}
+}
+
+static int pistachio_reset_assert(struct reset_controller_dev *rcdev,
+				  unsigned long id)
+{
+	struct pistachio_reset_data *rd;
+	u32 mask;
+	int shift;
+
+	rd = container_of(rcdev, struct pistachio_reset_data, rcdev);
+	shift = pistachio_reset_shift(id);
+	if (shift < 0)
+		return shift;
+	mask = BIT(shift);
+
+	return regmap_update_bits(rd->periph_regs, PISTACHIO_SOFT_RESET,
+				  mask, mask);
+}
+
+static int pistachio_reset_deassert(struct reset_controller_dev *rcdev,
+				    unsigned long id)
+{
+	struct pistachio_reset_data *rd;
+	u32 mask;
+	int shift;
+
+	rd = container_of(rcdev, struct pistachio_reset_data, rcdev);
+	shift = pistachio_reset_shift(id);
+	if (shift < 0)
+		return shift;
+	mask = BIT(shift);
+
+	return regmap_update_bits(rd->periph_regs, PISTACHIO_SOFT_RESET,
+				  mask, 0);
+}
+
+static const struct reset_control_ops pistachio_reset_ops = {
+	.assert		= pistachio_reset_assert,
+	.deassert	= pistachio_reset_deassert,
+};
+
+static int pistachio_reset_probe(struct platform_device *pdev)
+{
+	struct pistachio_reset_data *rd;
+	struct device *dev = &pdev->dev;
+	struct device_node *np = pdev->dev.of_node;
+
+	rd = devm_kzalloc(dev, sizeof(*rd), GFP_KERNEL);
+	if (!rd)
+		return -ENOMEM;
+
+	rd->periph_regs = syscon_node_to_regmap(np->parent);
+	if (IS_ERR(rd->periph_regs))
+		return PTR_ERR(rd->periph_regs);
+
+	rd->rcdev.owner = THIS_MODULE;
+	rd->rcdev.nr_resets = PISTACHIO_RESET_MAX + 1;
+	rd->rcdev.ops = &pistachio_reset_ops;
+	rd->rcdev.of_node = np;
+
+	return devm_reset_controller_register(dev, &rd->rcdev);
+}
+
+static const struct of_device_id pistachio_reset_dt_ids[] = {
+	 { .compatible = "img,pistachio-reset", },
+	 { /* sentinel */ },
+};
+
+static struct platform_driver pistachio_reset_driver = {
+	.probe	= pistachio_reset_probe,
+	.driver = {
+		.name		= "pistachio-reset",
+		.of_match_table	= pistachio_reset_dt_ids,
+	},
+};
+builtin_platform_driver(pistachio_reset_driver);