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, 209 insertions, 0 deletions

diff --git a/drivers/scsi/jazz_esp.c b/drivers/scsi/jazz_esp.c
new file mode 100644
index 000000000..35137f5cf
--- /dev/null
+++ b/drivers/scsi/jazz_esp.c
@@ -0,0 +1,209 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/* jazz_esp.c: ESP front-end for MIPS JAZZ systems.
+ *
+ * Copyright (C) 2007 Thomas Bogendörfer (tsbogend@alpha.frankende)
+ */
+
+#include <linux/kernel.h>
+#include <linux/gfp.h>
+#include <linux/types.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/platform_device.h>
+#include <linux/dma-mapping.h>
+
+#include <asm/irq.h>
+#include <asm/io.h>
+#include <asm/dma.h>
+
+#include <asm/jazz.h>
+#include <asm/jazzdma.h>
+
+#include <scsi/scsi_host.h>
+
+#include "esp_scsi.h"
+
+#define DRV_MODULE_NAME		"jazz_esp"
+#define PFX DRV_MODULE_NAME	": "
+#define DRV_VERSION		"1.000"
+#define DRV_MODULE_RELDATE	"May 19, 2007"
+
+static void jazz_esp_write8(struct esp *esp, u8 val, unsigned long reg)
+{
+	*(volatile u8 *)(esp->regs + reg) = val;
+}
+
+static u8 jazz_esp_read8(struct esp *esp, unsigned long reg)
+{
+	return *(volatile u8 *)(esp->regs + reg);
+}
+
+static int jazz_esp_irq_pending(struct esp *esp)
+{
+	if (jazz_esp_read8(esp, ESP_STATUS) & ESP_STAT_INTR)
+		return 1;
+	return 0;
+}
+
+static void jazz_esp_reset_dma(struct esp *esp)
+{
+	vdma_disable ((int)esp->dma_regs);
+}
+
+static void jazz_esp_dma_drain(struct esp *esp)
+{
+	/* nothing to do */
+}
+
+static void jazz_esp_dma_invalidate(struct esp *esp)
+{
+	vdma_disable ((int)esp->dma_regs);
+}
+
+static void jazz_esp_send_dma_cmd(struct esp *esp, u32 addr, u32 esp_count,
+				  u32 dma_count, int write, u8 cmd)
+{
+	BUG_ON(!(cmd & ESP_CMD_DMA));
+
+	jazz_esp_write8(esp, (esp_count >> 0) & 0xff, ESP_TCLOW);
+	jazz_esp_write8(esp, (esp_count >> 8) & 0xff, ESP_TCMED);
+	vdma_disable ((int)esp->dma_regs);
+	if (write)
+		vdma_set_mode ((int)esp->dma_regs, DMA_MODE_READ);
+	else
+		vdma_set_mode ((int)esp->dma_regs, DMA_MODE_WRITE);
+
+	vdma_set_addr ((int)esp->dma_regs, addr);
+	vdma_set_count ((int)esp->dma_regs, dma_count);
+	vdma_enable ((int)esp->dma_regs);
+
+	scsi_esp_cmd(esp, cmd);
+}
+
+static int jazz_esp_dma_error(struct esp *esp)
+{
+	u32 enable = vdma_get_enable((int)esp->dma_regs);
+
+	if (enable & (R4030_MEM_INTR|R4030_ADDR_INTR))
+		return 1;
+
+	return 0;
+}
+
+static const struct esp_driver_ops jazz_esp_ops = {
+	.esp_write8	=	jazz_esp_write8,
+	.esp_read8	=	jazz_esp_read8,
+	.irq_pending	=	jazz_esp_irq_pending,
+	.reset_dma	=	jazz_esp_reset_dma,
+	.dma_drain	=	jazz_esp_dma_drain,
+	.dma_invalidate	=	jazz_esp_dma_invalidate,
+	.send_dma_cmd	=	jazz_esp_send_dma_cmd,
+	.dma_error	=	jazz_esp_dma_error,
+};
+
+static int esp_jazz_probe(struct platform_device *dev)
+{
+	const struct scsi_host_template *tpnt = &scsi_esp_template;
+	struct Scsi_Host *host;
+	struct esp *esp;
+	struct resource *res;
+	int err;
+
+	host = scsi_host_alloc(tpnt, sizeof(struct esp));
+
+	err = -ENOMEM;
+	if (!host)
+		goto fail;
+
+	host->max_id = 8;
+	esp = shost_priv(host);
+
+	esp->host = host;
+	esp->dev = &dev->dev;
+	esp->ops = &jazz_esp_ops;
+
+	res = platform_get_resource(dev, IORESOURCE_MEM, 0);
+	if (!res)
+		goto fail_unlink;
+
+	esp->regs = (void __iomem *)res->start;
+	if (!esp->regs)
+		goto fail_unlink;
+
+	res = platform_get_resource(dev, IORESOURCE_MEM, 1);
+	if (!res)
+		goto fail_unlink;
+
+	esp->dma_regs = (void __iomem *)res->start;
+
+	esp->command_block = dma_alloc_coherent(esp->dev, 16,
+						&esp->command_block_dma,
+						GFP_KERNEL);
+	if (!esp->command_block)
+		goto fail_unmap_regs;
+
+	host->irq = err = platform_get_irq(dev, 0);
+	if (err < 0)
+		goto fail_unmap_command_block;
+	err = request_irq(host->irq, scsi_esp_intr, IRQF_SHARED, "ESP", esp);
+	if (err < 0)
+		goto fail_unmap_command_block;
+
+	esp->scsi_id = 7;
+	esp->host->this_id = esp->scsi_id;
+	esp->scsi_id_mask = (1 << esp->scsi_id);
+	esp->cfreq = 40000000;
+
+	dev_set_drvdata(&dev->dev, esp);
+
+	err = scsi_esp_register(esp);
+	if (err)
+		goto fail_free_irq;
+
+	return 0;
+
+fail_free_irq:
+	free_irq(host->irq, esp);
+fail_unmap_command_block:
+	dma_free_coherent(esp->dev, 16,
+			  esp->command_block,
+			  esp->command_block_dma);
+fail_unmap_regs:
+fail_unlink:
+	scsi_host_put(host);
+fail:
+	return err;
+}
+
+static void esp_jazz_remove(struct platform_device *dev)
+{
+	struct esp *esp = dev_get_drvdata(&dev->dev);
+	unsigned int irq = esp->host->irq;
+
+	scsi_esp_unregister(esp);
+
+	free_irq(irq, esp);
+	dma_free_coherent(esp->dev, 16,
+			  esp->command_block,
+			  esp->command_block_dma);
+
+	scsi_host_put(esp->host);
+}
+
+/* work with hotplug and coldplug */
+MODULE_ALIAS("platform:jazz_esp");
+
+static struct platform_driver esp_jazz_driver = {
+	.probe		= esp_jazz_probe,
+	.remove		= esp_jazz_remove,
+	.driver	= {
+		.name	= "jazz_esp",
+	},
+};
+module_platform_driver(esp_jazz_driver);
+
+MODULE_DESCRIPTION("JAZZ ESP SCSI driver");
+MODULE_AUTHOR("Thomas Bogendoerfer <tsbogend@alpha.franken.de>");
+MODULE_LICENSE("GPL");
+MODULE_VERSION(DRV_VERSION);