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, 142 insertions, 0 deletions

diff --git a/drivers/phy/broadcom/phy-bcm-ns-usb2.c b/drivers/phy/broadcom/phy-bcm-ns-usb2.c
new file mode 100644
index 000000000..c5d35031b
--- /dev/null
+++ b/drivers/phy/broadcom/phy-bcm-ns-usb2.c
@@ -0,0 +1,142 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Broadcom Northstar USB 2.0 PHY Driver
+ *
+ * Copyright (C) 2016 Rafał Miłecki <zajec5@gmail.com>
+ */
+
+#include <linux/bcma/bcma.h>
+#include <linux/clk.h>
+#include <linux/delay.h>
+#include <linux/err.h>
+#include <linux/mfd/syscon.h>
+#include <linux/module.h>
+#include <linux/of_address.h>
+#include <linux/of_platform.h>
+#include <linux/phy/phy.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+#include <linux/slab.h>
+
+struct bcm_ns_usb2 {
+	struct device *dev;
+	struct clk *ref_clk;
+	struct phy *phy;
+	struct regmap *clkset;
+	void __iomem *base;
+};
+
+static int bcm_ns_usb2_phy_init(struct phy *phy)
+{
+	struct bcm_ns_usb2 *usb2 = phy_get_drvdata(phy);
+	struct device *dev = usb2->dev;
+	u32 ref_clk_rate, usb2ctl, usb_pll_ndiv, usb_pll_pdiv;
+	int err = 0;
+
+	err = clk_prepare_enable(usb2->ref_clk);
+	if (err < 0) {
+		dev_err(dev, "Failed to prepare ref clock: %d\n", err);
+		goto err_out;
+	}
+
+	ref_clk_rate = clk_get_rate(usb2->ref_clk);
+	if (!ref_clk_rate) {
+		dev_err(dev, "Failed to get ref clock rate\n");
+		err = -EINVAL;
+		goto err_clk_off;
+	}
+
+	usb2ctl = readl(usb2->base);
+
+	if (usb2ctl & BCMA_DMU_CRU_USB2_CONTROL_USB_PLL_PDIV_MASK) {
+		usb_pll_pdiv = usb2ctl;
+		usb_pll_pdiv &= BCMA_DMU_CRU_USB2_CONTROL_USB_PLL_PDIV_MASK;
+		usb_pll_pdiv >>= BCMA_DMU_CRU_USB2_CONTROL_USB_PLL_PDIV_SHIFT;
+	} else {
+		usb_pll_pdiv = 1 << 3;
+	}
+
+	/* Calculate ndiv based on a solid 1920 MHz that is for USB2 PHY */
+	usb_pll_ndiv = (1920000000 * usb_pll_pdiv) / ref_clk_rate;
+
+	/* Unlock DMU PLL settings with some magic value */
+	regmap_write(usb2->clkset, 0, 0x0000ea68);
+
+	/* Write USB 2.0 PLL control setting */
+	usb2ctl &= ~BCMA_DMU_CRU_USB2_CONTROL_USB_PLL_NDIV_MASK;
+	usb2ctl |= usb_pll_ndiv << BCMA_DMU_CRU_USB2_CONTROL_USB_PLL_NDIV_SHIFT;
+
+	writel(usb2ctl, usb2->base);
+
+	/* Lock DMU PLL settings */
+	regmap_write(usb2->clkset, 0, 0x00000000);
+
+err_clk_off:
+	clk_disable_unprepare(usb2->ref_clk);
+err_out:
+	return err;
+}
+
+static const struct phy_ops ops = {
+	.init		= bcm_ns_usb2_phy_init,
+	.owner		= THIS_MODULE,
+};
+
+static int bcm_ns_usb2_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct bcm_ns_usb2 *usb2;
+	struct phy_provider *phy_provider;
+
+	usb2 = devm_kzalloc(&pdev->dev, sizeof(*usb2), GFP_KERNEL);
+	if (!usb2)
+		return -ENOMEM;
+	usb2->dev = dev;
+
+	usb2->base = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(usb2->base)) {
+		dev_err(dev, "Failed to map control reg\n");
+		return PTR_ERR(usb2->base);
+	}
+
+	usb2->clkset = syscon_regmap_lookup_by_phandle(dev->of_node,
+						       "brcm,syscon-clkset");
+	if (IS_ERR(usb2->clkset)) {
+		dev_err(dev, "Failed to lookup clkset regmap\n");
+		return PTR_ERR(usb2->clkset);
+	}
+
+	usb2->ref_clk = devm_clk_get(dev, "phy-ref-clk");
+	if (IS_ERR(usb2->ref_clk)) {
+		dev_err_probe(dev, PTR_ERR(usb2->ref_clk), "failed to get ref clk\n");
+		return PTR_ERR(usb2->ref_clk);
+	}
+
+	usb2->phy = devm_phy_create(dev, NULL, &ops);
+	if (IS_ERR(usb2->phy))
+		return PTR_ERR(usb2->phy);
+
+	phy_set_drvdata(usb2->phy, usb2);
+	platform_set_drvdata(pdev, usb2);
+
+	phy_provider = devm_of_phy_provider_register(dev, of_phy_simple_xlate);
+	return PTR_ERR_OR_ZERO(phy_provider);
+}
+
+static const struct of_device_id bcm_ns_usb2_id_table[] = {
+	{ .compatible = "brcm,ns-usb2-phy", },
+	{},
+};
+MODULE_DEVICE_TABLE(of, bcm_ns_usb2_id_table);
+
+static struct platform_driver bcm_ns_usb2_driver = {
+	.probe		= bcm_ns_usb2_probe,
+	.driver = {
+		.name = "bcm_ns_usb2",
+		.of_match_table = bcm_ns_usb2_id_table,
+	},
+};
+module_platform_driver(bcm_ns_usb2_driver);
+
+MODULE_DESCRIPTION("Broadcom Northstar USB 2.0 PHY Driver");
+MODULE_LICENSE("GPL v2");