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, 191 insertions, 0 deletions

diff --git a/drivers/sh/intc/internals.h b/drivers/sh/intc/internals.h
new file mode 100644
index 000000000..9b6cd1beb
--- /dev/null
+++ b/drivers/sh/intc/internals.h
@@ -0,0 +1,191 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#include <linux/sh_intc.h>
+#include <linux/irq.h>
+#include <linux/irqdomain.h>
+#include <linux/list.h>
+#include <linux/kernel.h>
+#include <linux/types.h>
+#include <linux/radix-tree.h>
+#include <linux/device.h>
+
+#define _INTC_MK(fn, mode, addr_e, addr_d, width, shift) \
+	((shift) | ((width) << 5) | ((fn) << 9) | ((mode) << 13) | \
+	 ((addr_e) << 16) | ((addr_d << 24)))
+
+#define _INTC_SHIFT(h)		(h & 0x1f)
+#define _INTC_WIDTH(h)		((h >> 5) & 0xf)
+#define _INTC_FN(h)		((h >> 9) & 0xf)
+#define _INTC_MODE(h)		((h >> 13) & 0x7)
+#define _INTC_ADDR_E(h)		((h >> 16) & 0xff)
+#define _INTC_ADDR_D(h)		((h >> 24) & 0xff)
+
+#ifdef CONFIG_SMP
+#define IS_SMP(x)		(x.smp)
+#define INTC_REG(d, x, c)	(d->reg[(x)] + ((d->smp[(x)] & 0xff) * c))
+#define SMP_NR(d, x)		((d->smp[(x)] >> 8) ? (d->smp[(x)] >> 8) : 1)
+#else
+#define IS_SMP(x)		0
+#define INTC_REG(d, x, c)	(d->reg[(x)])
+#define SMP_NR(d, x)		1
+#endif
+
+struct intc_handle_int {
+	unsigned int irq;
+	unsigned long handle;
+};
+
+struct intc_window {
+	phys_addr_t phys;
+	void __iomem *virt;
+	unsigned long size;
+};
+
+struct intc_map_entry {
+	intc_enum enum_id;
+	struct intc_desc_int *desc;
+};
+
+struct intc_subgroup_entry {
+	unsigned int pirq;
+	intc_enum enum_id;
+	unsigned long handle;
+};
+
+struct intc_desc_int {
+	struct list_head list;
+	struct device dev;
+	struct radix_tree_root tree;
+	raw_spinlock_t lock;
+	unsigned int index;
+	unsigned long *reg;
+#ifdef CONFIG_SMP
+	unsigned long *smp;
+#endif
+	unsigned int nr_reg;
+	struct intc_handle_int *prio;
+	unsigned int nr_prio;
+	struct intc_handle_int *sense;
+	unsigned int nr_sense;
+	struct intc_window *window;
+	unsigned int nr_windows;
+	struct irq_domain *domain;
+	struct irq_chip chip;
+	bool skip_suspend;
+};
+
+
+enum {
+	REG_FN_ERR = 0,
+	REG_FN_TEST_BASE = 1,
+	REG_FN_WRITE_BASE = 5,
+	REG_FN_MODIFY_BASE = 9
+};
+
+enum {	MODE_ENABLE_REG = 0, /* Bit(s) set -> interrupt enabled */
+	MODE_MASK_REG,       /* Bit(s) set -> interrupt disabled */
+	MODE_DUAL_REG,       /* Two registers, set bit to enable / disable */
+	MODE_PRIO_REG,       /* Priority value written to enable interrupt */
+	MODE_PCLR_REG,       /* Above plus all bits set to disable interrupt */
+};
+
+static inline struct intc_desc_int *get_intc_desc(unsigned int irq)
+{
+	struct irq_chip *chip = irq_get_chip(irq);
+
+	return container_of(chip, struct intc_desc_int, chip);
+}
+
+/*
+ * Grumble.
+ */
+static inline void activate_irq(int irq)
+{
+	irq_modify_status(irq, IRQ_NOREQUEST, IRQ_NOPROBE);
+}
+
+static inline int intc_handle_int_cmp(const void *a, const void *b)
+{
+	const struct intc_handle_int *_a = a;
+	const struct intc_handle_int *_b = b;
+
+	return _a->irq - _b->irq;
+}
+
+/* access.c */
+extern unsigned long
+(*intc_reg_fns[])(unsigned long addr, unsigned long h, unsigned long data);
+
+extern unsigned long
+(*intc_enable_fns[])(unsigned long addr, unsigned long handle,
+		     unsigned long (*fn)(unsigned long,
+				unsigned long, unsigned long),
+		     unsigned int irq);
+extern unsigned long
+(*intc_disable_fns[])(unsigned long addr, unsigned long handle,
+		      unsigned long (*fn)(unsigned long,
+				unsigned long, unsigned long),
+		      unsigned int irq);
+extern unsigned long
+(*intc_enable_noprio_fns[])(unsigned long addr, unsigned long handle,
+		            unsigned long (*fn)(unsigned long,
+				unsigned long, unsigned long),
+			    unsigned int irq);
+
+unsigned long intc_phys_to_virt(struct intc_desc_int *d, unsigned long address);
+unsigned int intc_get_reg(struct intc_desc_int *d, unsigned long address);
+unsigned int intc_set_field_from_handle(unsigned int value,
+			    unsigned int field_value,
+			    unsigned int handle);
+unsigned long intc_get_field_from_handle(unsigned int value,
+					 unsigned int handle);
+
+/* balancing.c */
+#ifdef CONFIG_INTC_BALANCING
+void intc_balancing_enable(unsigned int irq);
+void intc_balancing_disable(unsigned int irq);
+void intc_set_dist_handle(unsigned int irq, struct intc_desc *desc,
+			  struct intc_desc_int *d, intc_enum id);
+#else
+static inline void intc_balancing_enable(unsigned int irq) { }
+static inline void intc_balancing_disable(unsigned int irq) { }
+static inline void
+intc_set_dist_handle(unsigned int irq, struct intc_desc *desc,
+		     struct intc_desc_int *d, intc_enum id) { }
+#endif
+
+/* chip.c */
+extern struct irq_chip intc_irq_chip;
+void _intc_enable(struct irq_data *data, unsigned long handle);
+
+/* core.c */
+extern struct list_head intc_list;
+extern raw_spinlock_t intc_big_lock;
+extern const struct bus_type intc_subsys;
+
+unsigned int intc_get_dfl_prio_level(void);
+unsigned int intc_get_prio_level(unsigned int irq);
+void intc_set_prio_level(unsigned int irq, unsigned int level);
+
+/* handle.c */
+unsigned int intc_get_mask_handle(struct intc_desc *desc,
+				  struct intc_desc_int *d,
+				  intc_enum enum_id, int do_grps);
+unsigned int intc_get_prio_handle(struct intc_desc *desc,
+				  struct intc_desc_int *d,
+				  intc_enum enum_id, int do_grps);
+unsigned int intc_get_sense_handle(struct intc_desc *desc,
+				   struct intc_desc_int *d,
+				   intc_enum enum_id);
+void intc_set_ack_handle(unsigned int irq, struct intc_desc *desc,
+			 struct intc_desc_int *d, intc_enum id);
+unsigned long intc_get_ack_handle(unsigned int irq);
+void intc_enable_disable_enum(struct intc_desc *desc, struct intc_desc_int *d,
+			      intc_enum enum_id, int enable);
+
+/* irqdomain.c */
+void intc_irq_domain_init(struct intc_desc_int *d, struct intc_hw_desc *hw);
+
+/* virq.c */
+void intc_subgroup_init(struct intc_desc *desc, struct intc_desc_int *d);
+void intc_irq_xlate_set(unsigned int irq, intc_enum id, struct intc_desc_int *d);
+struct intc_map_entry *intc_irq_xlate_get(unsigned int irq);