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, 133 insertions, 0 deletions

diff --git a/drivers/reset/reset-bcm6345.c b/drivers/reset/reset-bcm6345.c
new file mode 100644
index 000000000..441d9dd76
--- /dev/null
+++ b/drivers/reset/reset-bcm6345.c
@@ -0,0 +1,133 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * BCM6345 Reset Controller Driver
+ *
+ * Copyright (C) 2020 Álvaro Fernández Rojas <noltari@gmail.com>
+ */
+
+#include <linux/delay.h>
+#include <linux/init.h>
+#include <linux/io.h>
+#include <linux/platform_device.h>
+#include <linux/reset-controller.h>
+
+#define BCM6345_RESET_NUM		32
+#define BCM6345_RESET_SLEEP_MIN_US	10000
+#define BCM6345_RESET_SLEEP_MAX_US	20000
+
+struct bcm6345_reset {
+	struct reset_controller_dev rcdev;
+	void __iomem *base;
+	spinlock_t lock;
+};
+
+static inline struct bcm6345_reset *
+to_bcm6345_reset(struct reset_controller_dev *rcdev)
+{
+	return container_of(rcdev, struct bcm6345_reset, rcdev);
+}
+
+static int bcm6345_reset_update(struct reset_controller_dev *rcdev,
+				unsigned long id, bool assert)
+{
+	struct bcm6345_reset *bcm6345_reset = to_bcm6345_reset(rcdev);
+	unsigned long flags;
+	uint32_t val;
+
+	spin_lock_irqsave(&bcm6345_reset->lock, flags);
+	val = __raw_readl(bcm6345_reset->base);
+	if (assert)
+		val &= ~BIT(id);
+	else
+		val |= BIT(id);
+	__raw_writel(val, bcm6345_reset->base);
+	spin_unlock_irqrestore(&bcm6345_reset->lock, flags);
+
+	return 0;
+}
+
+static int bcm6345_reset_assert(struct reset_controller_dev *rcdev,
+				unsigned long id)
+{
+	return bcm6345_reset_update(rcdev, id, true);
+}
+
+static int bcm6345_reset_deassert(struct reset_controller_dev *rcdev,
+				  unsigned long id)
+{
+	return bcm6345_reset_update(rcdev, id, false);
+}
+
+static int bcm6345_reset_reset(struct reset_controller_dev *rcdev,
+			       unsigned long id)
+{
+	bcm6345_reset_update(rcdev, id, true);
+	usleep_range(BCM6345_RESET_SLEEP_MIN_US,
+		     BCM6345_RESET_SLEEP_MAX_US);
+
+	bcm6345_reset_update(rcdev, id, false);
+	/*
+	 * Ensure component is taken out reset state by sleeping also after
+	 * deasserting the reset. Otherwise, the component may not be ready
+	 * for operation.
+	 */
+	usleep_range(BCM6345_RESET_SLEEP_MIN_US,
+		     BCM6345_RESET_SLEEP_MAX_US);
+
+	return 0;
+}
+
+static int bcm6345_reset_status(struct reset_controller_dev *rcdev,
+				unsigned long id)
+{
+	struct bcm6345_reset *bcm6345_reset = to_bcm6345_reset(rcdev);
+
+	return !(__raw_readl(bcm6345_reset->base) & BIT(id));
+}
+
+static const struct reset_control_ops bcm6345_reset_ops = {
+	.assert = bcm6345_reset_assert,
+	.deassert = bcm6345_reset_deassert,
+	.reset = bcm6345_reset_reset,
+	.status = bcm6345_reset_status,
+};
+
+static int bcm6345_reset_probe(struct platform_device *pdev)
+{
+	struct bcm6345_reset *bcm6345_reset;
+
+	bcm6345_reset = devm_kzalloc(&pdev->dev,
+				     sizeof(*bcm6345_reset), GFP_KERNEL);
+	if (!bcm6345_reset)
+		return -ENOMEM;
+
+	bcm6345_reset->base = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(bcm6345_reset->base))
+		return PTR_ERR(bcm6345_reset->base);
+
+	spin_lock_init(&bcm6345_reset->lock);
+	bcm6345_reset->rcdev.ops = &bcm6345_reset_ops;
+	bcm6345_reset->rcdev.owner = THIS_MODULE;
+	bcm6345_reset->rcdev.of_node = pdev->dev.of_node;
+	bcm6345_reset->rcdev.of_reset_n_cells = 1;
+	bcm6345_reset->rcdev.nr_resets = BCM6345_RESET_NUM;
+
+	return devm_reset_controller_register(&pdev->dev,
+					      &bcm6345_reset->rcdev);
+}
+
+static const struct of_device_id bcm6345_reset_of_match[] = {
+	{ .compatible = "brcm,bcm6345-reset" },
+	{ .compatible = "brcm,bcm63xx-ephy-ctrl" },
+	{ /* sentinel */ },
+};
+
+static struct platform_driver bcm6345_reset_driver = {
+	.probe = bcm6345_reset_probe,
+	.driver	= {
+		.name = "bcm6345-reset",
+		.of_match_table = bcm6345_reset_of_match,
+		.suppress_bind_attrs = true,
+	},
+};
+builtin_platform_driver(bcm6345_reset_driver);