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, 249 insertions, 0 deletions

diff --git a/drivers/usb/host/sl811.h b/drivers/usb/host/sl811.h
new file mode 100644
index 000000000..ba8c9aa7d
--- /dev/null
+++ b/drivers/usb/host/sl811.h
@@ -0,0 +1,249 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * SL811HS register declarations and HCD data structures
+ *
+ * Copyright (C) 2004 Psion Teklogix
+ * Copyright (C) 2004 David Brownell
+ * Copyright (C) 2001 Cypress Semiconductor Inc. 
+ */
+
+/*
+ * SL811HS has transfer registers, and control registers.  In host/master
+ * mode one set of registers is used; in peripheral/slave mode, another.
+ *  - SL11H only has some "A" transfer registers from 0x00-0x04
+ *  - SL811HS also has "B" registers from 0x08-0x0c
+ *  - SL811S (or HS in slave mode) has four A+B sets, at 00, 10, 20, 30
+ */
+
+#define SL811_EP_A(base)	((base) + 0)
+#define SL811_EP_B(base)	((base) + 8)
+
+#define SL811_HOST_BUF		0x00
+#define SL811_PERIPH_EP0	0x00
+#define SL811_PERIPH_EP1	0x10
+#define SL811_PERIPH_EP2	0x20
+#define SL811_PERIPH_EP3	0x30
+
+
+/* TRANSFER REGISTERS:  host and peripheral sides are similar
+ * except for the control models (master vs slave).
+ */
+#define SL11H_HOSTCTLREG	0
+#	define SL11H_HCTLMASK_ARM	0x01
+#	define SL11H_HCTLMASK_ENABLE	0x02
+#	define SL11H_HCTLMASK_IN	0x00
+#	define SL11H_HCTLMASK_OUT	0x04
+#	define SL11H_HCTLMASK_ISOCH	0x10
+#	define SL11H_HCTLMASK_AFTERSOF	0x20
+#	define SL11H_HCTLMASK_TOGGLE	0x40
+#	define SL11H_HCTLMASK_PREAMBLE	0x80
+#define SL11H_BUFADDRREG	1
+#define SL11H_BUFLNTHREG	2
+#define SL11H_PKTSTATREG	3	/* read */
+#	define SL11H_STATMASK_ACK	0x01
+#	define SL11H_STATMASK_ERROR	0x02
+#	define SL11H_STATMASK_TMOUT	0x04
+#	define SL11H_STATMASK_SEQ	0x08
+#	define SL11H_STATMASK_SETUP	0x10
+#	define SL11H_STATMASK_OVF	0x20
+#	define SL11H_STATMASK_NAK	0x40
+#	define SL11H_STATMASK_STALL	0x80
+#define SL11H_PIDEPREG		3	/* write */
+#	define	SL_SETUP	0xd0
+#	define	SL_IN		0x90
+#	define	SL_OUT		0x10
+#	define	SL_SOF		0x50
+#	define	SL_PREAMBLE	0xc0
+#	define	SL_NAK		0xa0
+#	define	SL_STALL	0xe0
+#	define	SL_DATA0	0x30
+#	define	SL_DATA1	0xb0
+#define SL11H_XFERCNTREG	4	/* read */
+#define SL11H_DEVADDRREG	4	/* write */
+
+
+/* CONTROL REGISTERS:  host and peripheral are very different.
+ */
+#define SL11H_CTLREG1		5
+#	define SL11H_CTL1MASK_SOF_ENA	0x01
+#	define SL11H_CTL1MASK_FORCE	0x18
+#		define SL11H_CTL1MASK_NORMAL	0x00
+#		define SL11H_CTL1MASK_SE0	0x08	/* reset */
+#		define SL11H_CTL1MASK_J		0x10
+#		define SL11H_CTL1MASK_K		0x18	/* resume */
+#	define SL11H_CTL1MASK_LSPD	0x20
+#	define SL11H_CTL1MASK_SUSPEND	0x40
+#define SL11H_IRQ_ENABLE	6
+#	define SL11H_INTMASK_DONE_A	0x01
+#	define SL11H_INTMASK_DONE_B	0x02
+#	define SL11H_INTMASK_SOFINTR	0x10
+#	define SL11H_INTMASK_INSRMV	0x20	/* to/from SE0 */
+#	define SL11H_INTMASK_RD		0x40
+#	define SL11H_INTMASK_DP		0x80	/* only in INTSTATREG */
+#define SL11S_ADDRESS		7
+
+/* 0x08-0x0c are for the B buffer (not in SL11) */
+
+#define SL11H_IRQ_STATUS	0x0D	/* write to ack */
+#define SL11H_HWREVREG		0x0E	/* read */
+#	define SL11H_HWRMASK_HWREV	0xF0
+#define SL11H_SOFLOWREG		0x0E	/* write */
+#define SL11H_SOFTMRREG		0x0F	/* read */
+
+/* a write to this register enables SL811HS features.
+ * HOST flag presumably overrides the chip input signal?
+ */
+#define SL811HS_CTLREG2		0x0F
+#	define SL811HS_CTL2MASK_SOF_MASK	0x3F
+#	define SL811HS_CTL2MASK_DSWAP		0x40
+#	define SL811HS_CTL2MASK_HOST		0x80
+
+#define SL811HS_CTL2_INIT	(SL811HS_CTL2MASK_HOST | 0x2e)
+
+
+/* DATA BUFFERS: registers from 0x10..0xff are for data buffers;
+ * that's 240 bytes, which we'll split evenly between A and B sides.
+ * Only ISO can use more than 64 bytes per packet.
+ * (The SL11S has 0x40..0xff for buffers.)
+ */
+#define H_MAXPACKET	120		/* bytes in A or B fifos */
+
+#define SL11H_DATA_START	0x10
+#define	SL811HS_PACKET_BUF(is_a)	((is_a) \
+		? SL11H_DATA_START \
+		: (SL11H_DATA_START + H_MAXPACKET))
+
+/*-------------------------------------------------------------------------*/
+
+#define	LOG2_PERIODIC_SIZE	5	/* arbitrary; this matches OHCI */
+#define	PERIODIC_SIZE		(1 << LOG2_PERIODIC_SIZE)
+
+struct sl811 {
+	spinlock_t		lock;
+	void __iomem		*addr_reg;
+	void __iomem		*data_reg;
+	struct sl811_platform_data	*board;
+
+	unsigned long		stat_insrmv;
+	unsigned long		stat_wake;
+	unsigned long		stat_sof;
+	unsigned long		stat_a;
+	unsigned long		stat_b;
+	unsigned long		stat_lost;
+	unsigned long		stat_overrun;
+
+	/* sw model */
+	struct timer_list	timer;
+	struct sl811h_ep	*next_periodic;
+	struct sl811h_ep	*next_async;
+
+	struct sl811h_ep	*active_a;
+	unsigned long		jiffies_a;
+	struct sl811h_ep	*active_b;
+	unsigned long		jiffies_b;
+
+	u32			port1;
+	u8			ctrl1, ctrl2, irq_enable;
+	u16			frame;
+
+	/* async schedule: control, bulk */
+	struct list_head	async;
+
+	/* periodic schedule: interrupt, iso */
+	u16			load[PERIODIC_SIZE];
+	struct sl811h_ep	*periodic[PERIODIC_SIZE];
+	unsigned		periodic_count;
+};
+
+static inline struct sl811 *hcd_to_sl811(struct usb_hcd *hcd)
+{
+	return (struct sl811 *) (hcd->hcd_priv);
+}
+
+static inline struct usb_hcd *sl811_to_hcd(struct sl811 *sl811)
+{
+	return container_of((void *) sl811, struct usb_hcd, hcd_priv);
+}
+
+struct sl811h_ep {
+	struct usb_host_endpoint *hep;
+	struct usb_device	*udev;
+
+	u8			defctrl;
+	u8			maxpacket;
+	u8			epnum;
+	u8			nextpid;
+
+	u16			error_count;
+	u16			nak_count;
+	u16			length;		/* of current packet */
+
+	/* periodic schedule */
+	u16			period;
+	u16			branch;
+	u16			load;
+	struct sl811h_ep	*next;
+
+	/* async schedule */
+	struct list_head	schedule;
+};
+
+/*-------------------------------------------------------------------------*/
+
+/* These register utilities should work for the SL811S register API too
+ * NOTE:  caller must hold sl811->lock.
+ */
+
+static inline u8 sl811_read(struct sl811 *sl811, int reg)
+{
+	writeb(reg, sl811->addr_reg);
+	return readb(sl811->data_reg);
+}
+
+static inline void sl811_write(struct sl811 *sl811, int reg, u8 val)
+{
+	writeb(reg, sl811->addr_reg);
+	writeb(val, sl811->data_reg);
+}
+
+static inline void
+sl811_write_buf(struct sl811 *sl811, int addr, const void *buf, size_t count)
+{
+	const u8	*data;
+	void __iomem	*data_reg;
+
+	if (!count)
+		return;
+	writeb(addr, sl811->addr_reg);
+
+	data = buf;
+	data_reg = sl811->data_reg;
+	do {
+		writeb(*data++, data_reg);
+	} while (--count);
+}
+
+static inline void
+sl811_read_buf(struct sl811 *sl811, int addr, void *buf, size_t count)
+{
+	u8 		*data;
+	void __iomem	*data_reg;
+
+	if (!count)
+		return;
+	writeb(addr, sl811->addr_reg);
+
+	data = buf;
+	data_reg = sl811->data_reg;
+	do {
+		*data++ = readb(data_reg);
+	} while (--count);
+}
+
+/*-------------------------------------------------------------------------*/
+
+#ifdef PACKET_TRACE
+#    define PACKET		pr_debug("sl811: "stuff)
+#else
+#    define PACKET(stuff...)	do{}while(0)
+#endif