From a5f7a5bb3b7f28ba7e4fa246775b29a0e5537255 Mon Sep 17 00:00:00 2001 From: Jinke Han Date: Tue, 8 Sep 2026 15:37:42 +0800 Subject: x86/kprobes: Fix crash when probing CS CALL instructions 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) Signed-off-by: Jinke Han Signed-off-by: Ingo Molnar Reviewed-by: Masami Hiramatsu (Google) Acked-by: Yafang Shao Acked-by: Borislav Petkov Cc: Peter Zijlstra Link: https://patch.msgid.link/20260908073742.GA10517@didi-ThinkCentre-M920t-N000 --- drivers/input/serio/pcips2.c | 217 +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 217 insertions(+) create mode 100644 drivers/input/serio/pcips2.c (limited to 'drivers/input/serio/pcips2.c') diff --git a/drivers/input/serio/pcips2.c b/drivers/input/serio/pcips2.c new file mode 100644 index 000000000..78f47b0ca --- /dev/null +++ b/drivers/input/serio/pcips2.c @@ -0,0 +1,217 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * linux/drivers/input/serio/pcips2.c + * + * Copyright (C) 2003 Russell King, All Rights Reserved. + * + * I'm not sure if this is a generic PS/2 PCI interface or specific to + * the Mobility Electronics docking station. + */ +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#define PS2_CTRL (0) +#define PS2_STATUS (1) +#define PS2_DATA (2) + +#define PS2_CTRL_CLK (1<<0) +#define PS2_CTRL_DAT (1<<1) +#define PS2_CTRL_TXIRQ (1<<2) +#define PS2_CTRL_ENABLE (1<<3) +#define PS2_CTRL_RXIRQ (1<<4) + +#define PS2_STAT_CLK (1<<0) +#define PS2_STAT_DAT (1<<1) +#define PS2_STAT_PARITY (1<<2) +#define PS2_STAT_RXFULL (1<<5) +#define PS2_STAT_TXBUSY (1<<6) +#define PS2_STAT_TXEMPTY (1<<7) + +struct pcips2_data { + struct serio *io; + unsigned int base; + struct pci_dev *dev; +}; + +static int pcips2_write(struct serio *io, unsigned char val) +{ + struct pcips2_data *ps2if = io->port_data; + unsigned int stat; + + do { + stat = inb(ps2if->base + PS2_STATUS); + cpu_relax(); + } while (!(stat & PS2_STAT_TXEMPTY)); + + outb(val, ps2if->base + PS2_DATA); + + return 0; +} + +static irqreturn_t pcips2_interrupt(int irq, void *devid) +{ + struct pcips2_data *ps2if = devid; + unsigned char status, scancode; + int handled = 0; + + do { + unsigned int flag; + + status = inb(ps2if->base + PS2_STATUS); + if (!(status & PS2_STAT_RXFULL)) + break; + handled = 1; + scancode = inb(ps2if->base + PS2_DATA); + if (status == 0xff && scancode == 0xff) + break; + + flag = (status & PS2_STAT_PARITY) ? 0 : SERIO_PARITY; + + if (hweight8(scancode) & 1) + flag ^= SERIO_PARITY; + + serio_interrupt(ps2if->io, scancode, flag); + } while (1); + return IRQ_RETVAL(handled); +} + +static void pcips2_flush_input(struct pcips2_data *ps2if) +{ + unsigned char status, scancode; + + do { + status = inb(ps2if->base + PS2_STATUS); + if (!(status & PS2_STAT_RXFULL)) + break; + scancode = inb(ps2if->base + PS2_DATA); + if (status == 0xff && scancode == 0xff) + break; + } while (1); +} + +static int pcips2_open(struct serio *io) +{ + struct pcips2_data *ps2if = io->port_data; + int ret, val = 0; + + outb(PS2_CTRL_ENABLE, ps2if->base); + pcips2_flush_input(ps2if); + + ret = request_irq(ps2if->dev->irq, pcips2_interrupt, IRQF_SHARED, + "pcips2", ps2if); + if (ret == 0) + val = PS2_CTRL_ENABLE | PS2_CTRL_RXIRQ; + + outb(val, ps2if->base); + + return ret; +} + +static void pcips2_close(struct serio *io) +{ + struct pcips2_data *ps2if = io->port_data; + + outb(0, ps2if->base); + + free_irq(ps2if->dev->irq, ps2if); +} + +static int pcips2_probe(struct pci_dev *dev, const struct pci_device_id *id) +{ + struct pcips2_data *ps2if; + struct serio *serio; + int ret; + + ret = pci_enable_device(dev); + if (ret) + goto out; + + ret = pci_request_regions(dev, "pcips2"); + if (ret) + goto disable; + + ps2if = kzalloc_obj(*ps2if); + serio = kzalloc_obj(*serio); + if (!ps2if || !serio) { + ret = -ENOMEM; + goto release; + } + + + serio->id.type = SERIO_8042; + serio->write = pcips2_write; + serio->open = pcips2_open; + serio->close = pcips2_close; + strscpy(serio->name, pci_name(dev), sizeof(serio->name)); + strscpy(serio->phys, dev_name(&dev->dev), sizeof(serio->phys)); + serio->port_data = ps2if; + serio->dev.parent = &dev->dev; + ps2if->io = serio; + ps2if->dev = dev; + ps2if->base = pci_resource_start(dev, 0); + + pci_set_drvdata(dev, ps2if); + + serio_register_port(ps2if->io); + return 0; + + release: + kfree(ps2if); + kfree(serio); + pci_release_regions(dev); + disable: + pci_disable_device(dev); + out: + return ret; +} + +static void pcips2_remove(struct pci_dev *dev) +{ + struct pcips2_data *ps2if = pci_get_drvdata(dev); + + serio_unregister_port(ps2if->io); + kfree(ps2if); + pci_release_regions(dev); + pci_disable_device(dev); +} + +static const struct pci_device_id pcips2_ids[] = { + { + .vendor = 0x14f2, /* MOBILITY */ + .device = 0x0123, /* Keyboard */ + .subvendor = PCI_ANY_ID, + .subdevice = PCI_ANY_ID, + .class = PCI_CLASS_INPUT_KEYBOARD << 8, + .class_mask = 0xffff00, + }, + { + .vendor = 0x14f2, /* MOBILITY */ + .device = 0x0124, /* Mouse */ + .subvendor = PCI_ANY_ID, + .subdevice = PCI_ANY_ID, + .class = PCI_CLASS_INPUT_MOUSE << 8, + .class_mask = 0xffff00, + }, + { 0, } +}; +MODULE_DEVICE_TABLE(pci, pcips2_ids); + +static struct pci_driver pcips2_driver = { + .name = "pcips2", + .id_table = pcips2_ids, + .probe = pcips2_probe, + .remove = pcips2_remove, +}; + +module_pci_driver(pcips2_driver); + +MODULE_LICENSE("GPL"); +MODULE_AUTHOR("Russell King "); +MODULE_DESCRIPTION("PCI PS/2 keyboard/mouse driver"); -- cgit v1.3.1