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, 271 insertions, 0 deletions

diff --git a/arch/mips/ath79/setup.c b/arch/mips/ath79/setup.c
new file mode 100644
index 000000000..4e18cdcf6
--- /dev/null
+++ b/arch/mips/ath79/setup.c
@@ -0,0 +1,271 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ *  Atheros AR71XX/AR724X/AR913X specific setup
+ *
+ *  Copyright (C) 2010-2011 Jaiganesh Narayanan <jnarayanan@atheros.com>
+ *  Copyright (C) 2008-2011 Gabor Juhos <juhosg@openwrt.org>
+ *  Copyright (C) 2008 Imre Kaloz <kaloz@openwrt.org>
+ *
+ *  Parts of this file are based on Atheros' 2.6.15/2.6.31 BSP
+ */
+
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/io.h>
+#include <linux/memblock.h>
+#include <linux/err.h>
+#include <linux/clk.h>
+#include <linux/of_clk.h>
+#include <linux/of_fdt.h>
+#include <linux/irqchip.h>
+
+#include <asm/bootinfo.h>
+#include <asm/idle.h>
+#include <asm/time.h>		/* for mips_hpt_frequency */
+#include <asm/reboot.h>		/* for _machine_{restart,halt} */
+#include <asm/prom.h>
+#include <asm/fw/fw.h>
+
+#include <asm/mach-ath79/ath79.h>
+#include <asm/mach-ath79/ar71xx_regs.h>
+#include "common.h"
+
+#define ATH79_SYS_TYPE_LEN	64
+
+static char ath79_sys_type[ATH79_SYS_TYPE_LEN];
+
+static void ath79_halt(void)
+{
+	while (1)
+		cpu_wait();
+}
+
+static void __init ath79_detect_sys_type(void)
+{
+	char *chip = "????";
+	u32 id;
+	u32 major;
+	u32 minor;
+	u32 rev = 0;
+	u32 ver = 1;
+
+	id = ath79_reset_rr(AR71XX_RESET_REG_REV_ID);
+	major = id & REV_ID_MAJOR_MASK;
+
+	switch (major) {
+	case REV_ID_MAJOR_AR71XX:
+		minor = id & AR71XX_REV_ID_MINOR_MASK;
+		rev = id >> AR71XX_REV_ID_REVISION_SHIFT;
+		rev &= AR71XX_REV_ID_REVISION_MASK;
+		switch (minor) {
+		case AR71XX_REV_ID_MINOR_AR7130:
+			ath79_soc = ATH79_SOC_AR7130;
+			chip = "7130";
+			break;
+
+		case AR71XX_REV_ID_MINOR_AR7141:
+			ath79_soc = ATH79_SOC_AR7141;
+			chip = "7141";
+			break;
+
+		case AR71XX_REV_ID_MINOR_AR7161:
+			ath79_soc = ATH79_SOC_AR7161;
+			chip = "7161";
+			break;
+		}
+		break;
+
+	case REV_ID_MAJOR_AR7240:
+		ath79_soc = ATH79_SOC_AR7240;
+		chip = "7240";
+		rev = id & AR724X_REV_ID_REVISION_MASK;
+		break;
+
+	case REV_ID_MAJOR_AR7241:
+		ath79_soc = ATH79_SOC_AR7241;
+		chip = "7241";
+		rev = id & AR724X_REV_ID_REVISION_MASK;
+		break;
+
+	case REV_ID_MAJOR_AR7242:
+		ath79_soc = ATH79_SOC_AR7242;
+		chip = "7242";
+		rev = id & AR724X_REV_ID_REVISION_MASK;
+		break;
+
+	case REV_ID_MAJOR_AR913X:
+		minor = id & AR913X_REV_ID_MINOR_MASK;
+		rev = id >> AR913X_REV_ID_REVISION_SHIFT;
+		rev &= AR913X_REV_ID_REVISION_MASK;
+		switch (minor) {
+		case AR913X_REV_ID_MINOR_AR9130:
+			ath79_soc = ATH79_SOC_AR9130;
+			chip = "9130";
+			break;
+
+		case AR913X_REV_ID_MINOR_AR9132:
+			ath79_soc = ATH79_SOC_AR9132;
+			chip = "9132";
+			break;
+		}
+		break;
+
+	case REV_ID_MAJOR_AR9330:
+		ath79_soc = ATH79_SOC_AR9330;
+		chip = "9330";
+		rev = id & AR933X_REV_ID_REVISION_MASK;
+		break;
+
+	case REV_ID_MAJOR_AR9331:
+		ath79_soc = ATH79_SOC_AR9331;
+		chip = "9331";
+		rev = id & AR933X_REV_ID_REVISION_MASK;
+		break;
+
+	case REV_ID_MAJOR_AR9341:
+		ath79_soc = ATH79_SOC_AR9341;
+		chip = "9341";
+		rev = id & AR934X_REV_ID_REVISION_MASK;
+		break;
+
+	case REV_ID_MAJOR_AR9342:
+		ath79_soc = ATH79_SOC_AR9342;
+		chip = "9342";
+		rev = id & AR934X_REV_ID_REVISION_MASK;
+		break;
+
+	case REV_ID_MAJOR_AR9344:
+		ath79_soc = ATH79_SOC_AR9344;
+		chip = "9344";
+		rev = id & AR934X_REV_ID_REVISION_MASK;
+		break;
+
+	case REV_ID_MAJOR_QCA9533_V2:
+		ver = 2;
+		ath79_soc_rev = 2;
+		fallthrough;
+	case REV_ID_MAJOR_QCA9533:
+		ath79_soc = ATH79_SOC_QCA9533;
+		chip = "9533";
+		rev = id & QCA953X_REV_ID_REVISION_MASK;
+		break;
+
+	case REV_ID_MAJOR_QCA9556:
+		ath79_soc = ATH79_SOC_QCA9556;
+		chip = "9556";
+		rev = id & QCA955X_REV_ID_REVISION_MASK;
+		break;
+
+	case REV_ID_MAJOR_QCA9558:
+		ath79_soc = ATH79_SOC_QCA9558;
+		chip = "9558";
+		rev = id & QCA955X_REV_ID_REVISION_MASK;
+		break;
+
+	case REV_ID_MAJOR_QCA956X:
+		ath79_soc = ATH79_SOC_QCA956X;
+		chip = "956X";
+		rev = id & QCA956X_REV_ID_REVISION_MASK;
+		break;
+
+	case REV_ID_MAJOR_QCN550X:
+		ath79_soc = ATH79_SOC_QCA956X;
+		chip = "550X";
+		rev = id & QCA956X_REV_ID_REVISION_MASK;
+		break;
+
+	case REV_ID_MAJOR_TP9343:
+		ath79_soc = ATH79_SOC_TP9343;
+		chip = "9343";
+		rev = id & QCA956X_REV_ID_REVISION_MASK;
+		break;
+
+	default:
+		panic("ath79: unknown SoC, id:0x%08x", id);
+	}
+
+	if (ver == 1)
+		ath79_soc_rev = rev;
+
+	if (soc_is_qca953x() || soc_is_qca955x() || soc_is_qca956x())
+		sprintf(ath79_sys_type, "Qualcomm Atheros QCA%s ver %u rev %u",
+			chip, ver, rev);
+	else if (soc_is_tp9343())
+		sprintf(ath79_sys_type, "Qualcomm Atheros TP%s rev %u",
+			chip, rev);
+	else
+		sprintf(ath79_sys_type, "Atheros AR%s rev %u", chip, rev);
+	pr_info("SoC: %s\n", ath79_sys_type);
+}
+
+const char *get_system_type(void)
+{
+	return ath79_sys_type;
+}
+
+unsigned int get_c0_compare_int(void)
+{
+	return CP0_LEGACY_COMPARE_IRQ;
+}
+
+void __init plat_mem_setup(void)
+{
+	void *dtb;
+
+	set_io_port_base(KSEG1);
+
+	/* Get the position of the FDT passed by the bootloader */
+	dtb = (void *)fw_getenvl("fdt_start");
+	if (dtb == NULL)
+		dtb = get_fdt();
+
+	if (dtb)
+		__dt_setup_arch((void *)KSEG0ADDR(dtb));
+
+	ath79_reset_base = ioremap(AR71XX_RESET_BASE,
+					   AR71XX_RESET_SIZE);
+	ath79_pll_base = ioremap(AR71XX_PLL_BASE,
+					 AR71XX_PLL_SIZE);
+	ath79_detect_sys_type();
+	ath79_ddr_ctrl_init();
+
+	detect_memory_region(0, ATH79_MEM_SIZE_MIN, ATH79_MEM_SIZE_MAX);
+
+	_machine_halt = ath79_halt;
+	pm_power_off = ath79_halt;
+}
+
+void __init plat_time_init(void)
+{
+	struct device_node *np;
+	struct clk *clk;
+	unsigned long cpu_clk_rate;
+
+	of_clk_init(NULL);
+
+	np = of_get_cpu_node(0, NULL);
+	if (!np) {
+		pr_err("Failed to get CPU node\n");
+		return;
+	}
+
+	clk = of_clk_get(np, 0);
+	if (IS_ERR(clk)) {
+		pr_err("Failed to get CPU clock: %ld\n", PTR_ERR(clk));
+		return;
+	}
+
+	cpu_clk_rate = clk_get_rate(clk);
+
+	pr_info("CPU clock: %lu.%03lu MHz\n",
+		cpu_clk_rate / 1000000, (cpu_clk_rate / 1000) % 1000);
+
+	mips_hpt_frequency = cpu_clk_rate / 2;
+
+	clk_put(clk);
+}
+
+void __init arch_init_irq(void)
+{
+	irqchip_init();
+}