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/parisc/asp.c b/drivers/parisc/asp.c
new file mode 100644
index 000000000..32af8f095
--- /dev/null
+++ b/drivers/parisc/asp.c
@@ -0,0 +1,133 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *	ASP Device Driver
+ *
+ *	(c) Copyright 2000 The Puffin Group Inc.
+ *
+ *	(c) 2000-2023 by Helge Deller <deller@gmx.de>
+ */
+
+#include <linux/errno.h>
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/module.h>
+#include <linux/types.h>
+#include <asm/io.h>
+#include <asm/led.h>
+
+#include "gsc.h"
+
+#define ASP_GSC_IRQ	3		/* hardcoded interrupt for GSC */
+
+#define ASP_VER_OFFSET 	0x20		/* offset of ASP version */
+
+#define ASP_LED_ADDR	0xf0800020
+
+#define VIPER_INT_WORD  0xFFFBF088      /* addr of viper interrupt word */
+
+static struct gsc_asic asp;
+
+static void asp_choose_irq(struct parisc_device *dev, void *ctrl)
+{
+	int irq;
+
+	switch (dev->id.sversion) {
+	case 0x71:	irq =  9; break; /* SCSI */
+	case 0x72:	irq =  8; break; /* LAN */
+	case 0x73:	irq =  1; break; /* HIL */
+	case 0x74:	irq =  7; break; /* Centronics */
+	case 0x75:	irq = (dev->hw_path == 4) ? 5 : 6; break; /* RS232 */
+	case 0x76:	irq = 10; break; /* EISA BA */
+	case 0x77:	irq = 11; break; /* Graphics1 */
+	case 0x7a:	irq = 13; break; /* Audio (Bushmaster) */
+	case 0x7b:	irq = 13; break; /* Audio (Scorpio) */
+	case 0x7c:	irq =  3; break; /* FW SCSI */
+	case 0x7d:	irq =  4; break; /* FDDI */
+	case 0x7f:	irq = 13; break; /* Audio (Outfield) */
+	default:	return;		 /* Unknown */
+	}
+
+	gsc_asic_assign_irq(ctrl, irq, &dev->irq);
+
+	switch (dev->id.sversion) {
+	case 0x73:	irq =  2; break; /* i8042 High-priority */
+	case 0x76:	irq =  0; break; /* EISA BA */
+	default:	return;		 /* Other */
+	}
+
+	gsc_asic_assign_irq(ctrl, irq, &dev->aux_irq);
+}
+
+/* There are two register ranges we're interested in.  Interrupt /
+ * Status / LED are at 0xf080xxxx and Asp special registers are at
+ * 0xf082fxxx.  PDC only tells us that Asp is at 0xf082f000, so for
+ * the purposes of interrupt handling, we have to tell other bits of
+ * the kernel to look at the other registers.
+ */
+#define ASP_INTERRUPT_ADDR 0xf0800000
+
+static int __init asp_init_chip(struct parisc_device *dev)
+{
+	struct gsc_irq gsc_irq;
+	int ret;
+
+	asp.version = gsc_readb(dev->hpa.start + ASP_VER_OFFSET) & 0xf;
+	asp.name = (asp.version == 1) ? "Asp" : "Cutoff";
+	asp.hpa = ASP_INTERRUPT_ADDR;
+
+	printk(KERN_INFO "%s version %d at 0x%lx found.\n", 
+		asp.name, asp.version, (unsigned long)dev->hpa.start);
+
+	/* the IRQ ASP should use */
+	ret = -EBUSY;
+	dev->irq = gsc_claim_irq(&gsc_irq, ASP_GSC_IRQ);
+	if (dev->irq < 0) {
+		printk(KERN_ERR "%s(): cannot get GSC irq\n", __func__);
+		goto out;
+	}
+
+	asp.eim = ((u32) gsc_irq.txn_addr) | gsc_irq.txn_data;
+
+	ret = request_irq(gsc_irq.irq, gsc_asic_intr, 0, "asp", &asp);
+	if (ret < 0)
+		goto out;
+
+	/* Program VIPER to interrupt on the ASP irq */
+	gsc_writel((1 << (31 - ASP_GSC_IRQ)),VIPER_INT_WORD);
+
+	/* Done init'ing, register this driver */
+	ret = gsc_common_setup(dev, &asp);
+	if (ret)
+		goto out;
+
+	gsc_fixup_irqs(dev, &asp, asp_choose_irq);
+	/* Mongoose is a sibling of Asp, not a child... */
+	gsc_fixup_irqs(parisc_parent(dev), &asp, asp_choose_irq);
+
+	/* initialize the chassis LEDs */ 
+#ifdef CONFIG_CHASSIS_LCD_LED	
+	register_led_driver(DISPLAY_MODEL_OLD_ASP, LED_CMD_REG_NONE, 
+		    ASP_LED_ADDR);
+#endif
+
+ out:
+	return ret;
+}
+
+static const struct parisc_device_id asp_tbl[] __initconst = {
+	{ HPHW_BA, HVERSION_REV_ANY_ID, HVERSION_ANY_ID, 0x00070 },
+	{ 0, }
+};
+MODULE_DEVICE_TABLE(parisc, asp_tbl);
+
+static struct parisc_driver asp_driver __refdata = {
+	.name =		"asp",
+	.id_table =	asp_tbl,
+	.probe =	asp_init_chip,
+};
+
+static int __init asp_init(void)
+{
+	return register_parisc_driver(&asp_driver);
+}
+arch_initcall(asp_init);