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, 211 insertions, 0 deletions

diff --git a/drivers/sh/intc/chip.c b/drivers/sh/intc/chip.c
new file mode 100644
index 000000000..828d81e02
--- /dev/null
+++ b/drivers/sh/intc/chip.c
@@ -0,0 +1,211 @@
+/*
+ * IRQ chip definitions for INTC IRQs.
+ *
+ * Copyright (C) 2007, 2008 Magnus Damm
+ * Copyright (C) 2009 - 2012 Paul Mundt
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file "COPYING" in the main directory of this archive
+ * for more details.
+ */
+#include <linux/cpumask.h>
+#include <linux/bsearch.h>
+#include <linux/io.h>
+#include "internals.h"
+
+void _intc_enable(struct irq_data *data, unsigned long handle)
+{
+	unsigned int irq = data->irq;
+	struct intc_desc_int *d = get_intc_desc(irq);
+	unsigned long addr;
+	unsigned int cpu;
+
+	for (cpu = 0; cpu < SMP_NR(d, _INTC_ADDR_E(handle)); cpu++) {
+#ifdef CONFIG_SMP
+		if (!cpumask_test_cpu(cpu, irq_data_get_affinity_mask(data)))
+			continue;
+#endif
+		addr = INTC_REG(d, _INTC_ADDR_E(handle), cpu);
+		intc_enable_fns[_INTC_MODE(handle)](addr, handle, intc_reg_fns\
+						    [_INTC_FN(handle)], irq);
+	}
+
+	intc_balancing_enable(irq);
+}
+
+static void intc_enable(struct irq_data *data)
+{
+	_intc_enable(data, (unsigned long)irq_data_get_irq_chip_data(data));
+}
+
+static void intc_disable(struct irq_data *data)
+{
+	unsigned int irq = data->irq;
+	struct intc_desc_int *d = get_intc_desc(irq);
+	unsigned long handle = (unsigned long)irq_data_get_irq_chip_data(data);
+	unsigned long addr;
+	unsigned int cpu;
+
+	intc_balancing_disable(irq);
+
+	for (cpu = 0; cpu < SMP_NR(d, _INTC_ADDR_D(handle)); cpu++) {
+#ifdef CONFIG_SMP
+		if (!cpumask_test_cpu(cpu, irq_data_get_affinity_mask(data)))
+			continue;
+#endif
+		addr = INTC_REG(d, _INTC_ADDR_D(handle), cpu);
+		intc_disable_fns[_INTC_MODE(handle)](addr, handle,intc_reg_fns\
+						     [_INTC_FN(handle)], irq);
+	}
+}
+
+#ifdef CONFIG_SMP
+/*
+ * This is held with the irq desc lock held, so we don't require any
+ * additional locking here at the intc desc level. The affinity mask is
+ * later tested in the enable/disable paths.
+ */
+static int intc_set_affinity(struct irq_data *data,
+			     const struct cpumask *cpumask,
+			     bool force)
+{
+	if (!cpumask_intersects(cpumask, cpu_online_mask))
+		return -1;
+
+	irq_data_update_affinity(data, cpumask);
+
+	return IRQ_SET_MASK_OK_NOCOPY;
+}
+#endif
+
+static void intc_mask_ack(struct irq_data *data)
+{
+	unsigned int irq = data->irq;
+	struct intc_desc_int *d = get_intc_desc(irq);
+	unsigned long handle = intc_get_ack_handle(irq);
+	void __iomem *addr;
+
+	intc_disable(data);
+
+	/* read register and write zero only to the associated bit */
+	if (handle) {
+		unsigned int value;
+
+		addr = (void __iomem *)INTC_REG(d, _INTC_ADDR_D(handle), 0);
+		value = intc_set_field_from_handle(0, 1, handle);
+
+		switch (_INTC_FN(handle)) {
+		case REG_FN_MODIFY_BASE + 0:	/* 8bit */
+			__raw_readb(addr);
+			__raw_writeb(0xff ^ value, addr);
+			break;
+		case REG_FN_MODIFY_BASE + 1:	/* 16bit */
+			__raw_readw(addr);
+			__raw_writew(0xffff ^ value, addr);
+			break;
+		case REG_FN_MODIFY_BASE + 3:	/* 32bit */
+			__raw_readl(addr);
+			__raw_writel(0xffffffff ^ value, addr);
+			break;
+		default:
+			BUG();
+			break;
+		}
+	}
+}
+
+static struct intc_handle_int *intc_find_irq(struct intc_handle_int *hp,
+					     unsigned int nr_hp,
+					     unsigned int irq)
+{
+	struct intc_handle_int key;
+
+	key.irq = irq;
+	key.handle = 0;
+
+	return bsearch(&key, hp, nr_hp, sizeof(*hp), intc_handle_int_cmp);
+}
+
+int intc_set_priority(unsigned int irq, unsigned int prio)
+{
+	struct intc_desc_int *d = get_intc_desc(irq);
+	struct irq_data *data = irq_get_irq_data(irq);
+	struct intc_handle_int *ihp;
+
+	if (!intc_get_prio_level(irq) || prio <= 1)
+		return -EINVAL;
+
+	ihp = intc_find_irq(d->prio, d->nr_prio, irq);
+	if (ihp) {
+		if (prio >= (1 << _INTC_WIDTH(ihp->handle)))
+			return -EINVAL;
+
+		intc_set_prio_level(irq, prio);
+
+		/*
+		 * only set secondary masking method directly
+		 * primary masking method is using intc_prio_level[irq]
+		 * priority level will be set during next enable()
+		 */
+		if (_INTC_FN(ihp->handle) != REG_FN_ERR)
+			_intc_enable(data, ihp->handle);
+	}
+	return 0;
+}
+
+#define SENSE_VALID_FLAG 0x80
+#define VALID(x) (x | SENSE_VALID_FLAG)
+
+static unsigned char intc_irq_sense_table[IRQ_TYPE_SENSE_MASK + 1] = {
+	[IRQ_TYPE_EDGE_FALLING] = VALID(0),
+	[IRQ_TYPE_EDGE_RISING] = VALID(1),
+	[IRQ_TYPE_LEVEL_LOW] = VALID(2),
+	/* SH7706, SH7707 and SH7709 do not support high level triggered */
+#if !defined(CONFIG_CPU_SUBTYPE_SH7706) && \
+    !defined(CONFIG_CPU_SUBTYPE_SH7707) && \
+    !defined(CONFIG_CPU_SUBTYPE_SH7709)
+	[IRQ_TYPE_LEVEL_HIGH] = VALID(3),
+#endif
+#if defined(CONFIG_ARM) /* all recent SH-Mobile / R-Mobile ARM support this */
+	[IRQ_TYPE_EDGE_BOTH] = VALID(4),
+#endif
+};
+
+static int intc_set_type(struct irq_data *data, unsigned int type)
+{
+	unsigned int irq = data->irq;
+	struct intc_desc_int *d = get_intc_desc(irq);
+	unsigned char value = intc_irq_sense_table[type & IRQ_TYPE_SENSE_MASK];
+	struct intc_handle_int *ihp;
+	unsigned long addr;
+
+	if (!value)
+		return -EINVAL;
+
+	value &= ~SENSE_VALID_FLAG;
+
+	ihp = intc_find_irq(d->sense, d->nr_sense, irq);
+	if (ihp) {
+		/* PINT has 2-bit sense registers, should fail on EDGE_BOTH */
+		if (value >= (1 << _INTC_WIDTH(ihp->handle)))
+			return -EINVAL;
+
+		addr = INTC_REG(d, _INTC_ADDR_E(ihp->handle), 0);
+		intc_reg_fns[_INTC_FN(ihp->handle)](addr, ihp->handle, value);
+	}
+
+	return 0;
+}
+
+struct irq_chip intc_irq_chip	= {
+	.irq_mask		= intc_disable,
+	.irq_unmask		= intc_enable,
+	.irq_mask_ack		= intc_mask_ack,
+	.irq_enable		= intc_enable,
+	.irq_disable		= intc_disable,
+	.irq_set_type		= intc_set_type,
+#ifdef CONFIG_SMP
+	.irq_set_affinity	= intc_set_affinity,
+#endif
+	.flags			= IRQCHIP_SKIP_SET_WAKE,
+};