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, 114 insertions, 0 deletions

diff --git a/drivers/scsi/fdomain.h b/drivers/scsi/fdomain.h
new file mode 100644
index 000000000..93afcee20
--- /dev/null
+++ b/drivers/scsi/fdomain.h
@@ -0,0 +1,114 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#define FDOMAIN_REGION_SIZE	0x10
+#define FDOMAIN_BIOS_SIZE	0x2000
+
+enum {
+	in_arbitration	= 0x02,
+	in_selection	= 0x04,
+	in_other	= 0x08,
+	disconnect	= 0x10,
+	aborted		= 0x20,
+	sent_ident	= 0x40,
+};
+
+/* (@) = not present on TMC1800, (#) = not present on TMC1800 and TMC18C50 */
+#define REG_SCSI_DATA		0	/* R/W: SCSI Data (with ACK) */
+#define REG_BSTAT		1	/* R: SCSI Bus Status */
+#define		BSTAT_BSY	BIT(0)	 /* Busy */
+#define		BSTAT_MSG	BIT(1)	 /* Message */
+#define		BSTAT_IO	BIT(2)	 /* Input/Output */
+#define		BSTAT_CMD	BIT(3)	 /* Command/Data */
+#define		BSTAT_REQ	BIT(4)	 /* Request and Not Ack */
+#define		BSTAT_SEL	BIT(5)	 /* Select */
+#define		BSTAT_ACK	BIT(6)	 /* Acknowledge and Request */
+#define		BSTAT_ATN	BIT(7)	 /* Attention */
+#define REG_BCTL		1	/* W: SCSI Bus Control */
+#define		BCTL_RST	BIT(0)	 /* Bus Reset */
+#define		BCTL_SEL	BIT(1)	 /* Select */
+#define		BCTL_BSY	BIT(2)	 /* Busy */
+#define		BCTL_ATN	BIT(3)	 /* Attention */
+#define		BCTL_IO		BIT(4)	 /* Input/Output */
+#define		BCTL_CMD	BIT(5)	 /* Command/Data */
+#define		BCTL_MSG	BIT(6)	 /* Message */
+#define		BCTL_BUSEN	BIT(7)	 /* Enable bus drivers */
+#define REG_ASTAT		2	/* R: Adapter Status 1 */
+#define		ASTAT_IRQ	BIT(0)	 /* Interrupt active */
+#define		ASTAT_ARB	BIT(1)	 /* Arbitration complete */
+#define		ASTAT_PARERR	BIT(2)	 /* Parity error */
+#define		ASTAT_RST	BIT(3)	 /* SCSI reset occurred */
+#define		ASTAT_FIFODIR	BIT(4)	 /* FIFO direction */
+#define		ASTAT_FIFOEN	BIT(5)	 /* FIFO enabled */
+#define		ASTAT_PAREN	BIT(6)	 /* Parity enabled */
+#define		ASTAT_BUSEN	BIT(7)	 /* Bus drivers enabled */
+#define REG_ICTL		2	/* W: Interrupt Control */
+#define		ICTL_FIFO_MASK	0x0f	 /* FIFO threshold, 1/16 FIFO size */
+#define		ICTL_FIFO	BIT(4)	 /* Int. on FIFO count */
+#define		ICTL_ARB	BIT(5)	 /* Int. on Arbitration complete */
+#define		ICTL_SEL	BIT(6)	 /* Int. on SCSI Select */
+#define		ICTL_REQ	BIT(7)	 /* Int. on SCSI Request */
+#define REG_FSTAT		3	/* R: Adapter Status 2 (FIFO) - (@) */
+#define		FSTAT_ONOTEMPTY	BIT(0)	 /* Output FIFO not empty */
+#define		FSTAT_INOTEMPTY	BIT(1)	 /* Input FIFO not empty */
+#define		FSTAT_NOTEMPTY	BIT(2)	 /* Main FIFO not empty */
+#define		FSTAT_NOTFULL	BIT(3)	 /* Main FIFO not full */
+#define REG_MCTL		3	/* W: SCSI Data Mode Control */
+#define		MCTL_ACK_MASK	0x0f	 /* Acknowledge period */
+#define		MCTL_ACTDEASS	BIT(4)	 /* Active deassert of REQ and ACK */
+#define		MCTL_TARGET	BIT(5)	 /* Enable target mode */
+#define		MCTL_FASTSYNC	BIT(6)	 /* Enable Fast Synchronous */
+#define		MCTL_SYNC	BIT(7)	 /* Enable Synchronous */
+#define REG_INTCOND		4	/* R: Interrupt Condition - (@) */
+#define		IRQ_FIFO	BIT(1)	 /* FIFO interrupt */
+#define		IRQ_REQ		BIT(2)	 /* SCSI Request interrupt */
+#define		IRQ_SEL		BIT(3)	 /* SCSI Select interrupt */
+#define		IRQ_ARB		BIT(4)	 /* SCSI Arbitration interrupt */
+#define		IRQ_RST		BIT(5)	 /* SCSI Reset interrupt */
+#define		IRQ_FORCED	BIT(6)	 /* Forced interrupt */
+#define		IRQ_TIMEOUT	BIT(7)	 /* Bus timeout */
+#define REG_ACTL		4	/* W: Adapter Control 1 */
+#define		ACTL_RESET	BIT(0)	 /* Reset FIFO, parity, reset int. */
+#define		ACTL_FIRQ	BIT(1)	 /* Set Forced interrupt */
+#define		ACTL_ARB	BIT(2)	 /* Initiate Bus Arbitration */
+#define		ACTL_PAREN	BIT(3)	 /* Enable SCSI Parity */
+#define		ACTL_IRQEN	BIT(4)	 /* Enable interrupts */
+#define		ACTL_CLRFIRQ	BIT(5)	 /* Clear Forced interrupt */
+#define		ACTL_FIFOWR	BIT(6)	 /* FIFO Direction (1=write) */
+#define		ACTL_FIFOEN	BIT(7)	 /* Enable FIFO */
+#define REG_ID_LSB		5	/* R: ID Code (LSB) */
+#define REG_ACTL2		5	/* Adapter Control 2 - (@) */
+#define		ACTL2_RAMOVRLY	BIT(0)	 /* Enable RAM overlay */
+#define		ACTL2_SLEEP	BIT(7)	 /* Sleep mode */
+#define REG_ID_MSB		6	/* R: ID Code (MSB) */
+#define REG_LOOPBACK		7	/* R/W: Loopback */
+#define REG_SCSI_DATA_NOACK	8	/* R/W: SCSI Data (no ACK) */
+#define REG_ASTAT3		9	/* R: Adapter Status 3 */
+#define		ASTAT3_ACTDEASS	BIT(0)	 /* Active deassert enabled */
+#define		ASTAT3_RAMOVRLY	BIT(1)	 /* RAM overlay enabled */
+#define		ASTAT3_TARGERR	BIT(2)	 /* Target error */
+#define		ASTAT3_IRQEN	BIT(3)	 /* Interrupts enabled */
+#define		ASTAT3_IRQMASK	0xf0	 /* Enabled interrupts mask */
+#define REG_CFG1		10	/* R: Configuration Register 1 */
+#define		CFG1_BUS	BIT(0)	 /* 0 = ISA */
+#define		CFG1_IRQ_MASK	0x0e	 /* IRQ jumpers */
+#define		CFG1_IO_MASK	0x30	 /* I/O base jumpers */
+#define		CFG1_BIOS_MASK	0xc0	 /* BIOS base jumpers */
+#define REG_CFG2		11	/* R/W: Configuration Register 2 (@) */
+#define		CFG2_ROMDIS	BIT(0)	 /* ROM disabled */
+#define		CFG2_RAMDIS	BIT(1)	 /* RAM disabled */
+#define		CFG2_IRQEDGE	BIT(2)	 /* Edge-triggered interrupts */
+#define		CFG2_NOWS	BIT(3)	 /* No wait states */
+#define		CFG2_32BIT	BIT(7)	 /* 32-bit mode */
+#define REG_FIFO		12	/* R/W: FIFO */
+#define REG_FIFO_COUNT		14	/* R: FIFO Data Count */
+
+#ifdef CONFIG_PM_SLEEP
+static const struct dev_pm_ops __maybe_unused fdomain_pm_ops;
+#define FDOMAIN_PM_OPS	(&fdomain_pm_ops)
+#else
+#define FDOMAIN_PM_OPS	NULL
+#endif /* CONFIG_PM_SLEEP */
+
+struct Scsi_Host *fdomain_create(int base, int irq, int this_id,
+				 struct device *dev);
+int fdomain_destroy(struct Scsi_Host *sh);