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, 447 insertions, 0 deletions

diff --git a/net/dsa/trace.h b/net/dsa/trace.h
new file mode 100644
index 000000000..83f3e5f78
--- /dev/null
+++ b/net/dsa/trace.h
@@ -0,0 +1,447 @@
+/* SPDX-License-Identifier: GPL-2.0
+ * Copyright 2022-2023 NXP
+ */
+
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM	dsa
+
+#if !defined(_NET_DSA_TRACE_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _NET_DSA_TRACE_H
+
+#include <net/dsa.h>
+#include <net/switchdev.h>
+#include <linux/etherdevice.h>
+#include <linux/if_bridge.h>
+#include <linux/refcount.h>
+#include <linux/tracepoint.h>
+
+/* Enough to fit "bridge %s num %d" where num has 3 digits */
+#define DSA_DB_BUFSIZ	(IFNAMSIZ + 16)
+
+void dsa_db_print(const struct dsa_db *db, char buf[DSA_DB_BUFSIZ]);
+const char *dsa_port_kind(const struct dsa_port *dp);
+
+DECLARE_EVENT_CLASS(dsa_port_addr_op_hw,
+
+	TP_PROTO(const struct dsa_port *dp, const unsigned char *addr, u16 vid,
+		 const struct dsa_db *db, int err),
+
+	TP_ARGS(dp, addr, vid, db, err),
+
+	TP_STRUCT__entry(
+		__string(dev, dev_name(dp->ds->dev))
+		__string(kind, dsa_port_kind(dp))
+		__field(int, port)
+		__array(unsigned char, addr, ETH_ALEN)
+		__field(u16, vid)
+		__array(char, db_buf, DSA_DB_BUFSIZ)
+		__field(int, err)
+	),
+
+	TP_fast_assign(
+		__assign_str(dev);
+		__assign_str(kind);
+		__entry->port = dp->index;
+		ether_addr_copy(__entry->addr, addr);
+		__entry->vid = vid;
+		dsa_db_print(db, __entry->db_buf);
+		__entry->err = err;
+	),
+
+	TP_printk("%s %s port %d addr %pM vid %u db \"%s\" err %d",
+		  __get_str(dev), __get_str(kind), __entry->port, __entry->addr,
+		  __entry->vid, __entry->db_buf, __entry->err)
+);
+
+/* Add unicast/multicast address to hardware, either on user ports
+ * (where no refcounting is kept), or on shared ports when the entry
+ * is first seen and its refcount is 1.
+ */
+DEFINE_EVENT(dsa_port_addr_op_hw, dsa_fdb_add_hw,
+	     TP_PROTO(const struct dsa_port *dp, const unsigned char *addr,
+		      u16 vid, const struct dsa_db *db, int err),
+	     TP_ARGS(dp, addr, vid, db, err));
+
+DEFINE_EVENT(dsa_port_addr_op_hw, dsa_mdb_add_hw,
+	     TP_PROTO(const struct dsa_port *dp, const unsigned char *addr,
+		      u16 vid, const struct dsa_db *db, int err),
+	     TP_ARGS(dp, addr, vid, db, err));
+
+/* Delete unicast/multicast address from hardware, either on user ports or
+ * when the refcount on shared ports reaches 0
+ */
+DEFINE_EVENT(dsa_port_addr_op_hw, dsa_fdb_del_hw,
+	     TP_PROTO(const struct dsa_port *dp, const unsigned char *addr,
+		      u16 vid, const struct dsa_db *db, int err),
+	     TP_ARGS(dp, addr, vid, db, err));
+
+DEFINE_EVENT(dsa_port_addr_op_hw, dsa_mdb_del_hw,
+	     TP_PROTO(const struct dsa_port *dp, const unsigned char *addr,
+		      u16 vid, const struct dsa_db *db, int err),
+	     TP_ARGS(dp, addr, vid, db, err));
+
+DECLARE_EVENT_CLASS(dsa_port_addr_op_refcount,
+
+	TP_PROTO(const struct dsa_port *dp, const unsigned char *addr, u16 vid,
+		 const struct dsa_db *db, const refcount_t *refcount),
+
+	TP_ARGS(dp, addr, vid, db, refcount),
+
+	TP_STRUCT__entry(
+		__string(dev, dev_name(dp->ds->dev))
+		__string(kind, dsa_port_kind(dp))
+		__field(int, port)
+		__array(unsigned char, addr, ETH_ALEN)
+		__field(u16, vid)
+		__array(char, db_buf, DSA_DB_BUFSIZ)
+		__field(unsigned int, refcount)
+	),
+
+	TP_fast_assign(
+		__assign_str(dev);
+		__assign_str(kind);
+		__entry->port = dp->index;
+		ether_addr_copy(__entry->addr, addr);
+		__entry->vid = vid;
+		dsa_db_print(db, __entry->db_buf);
+		__entry->refcount = refcount_read(refcount);
+	),
+
+	TP_printk("%s %s port %d addr %pM vid %u db \"%s\" refcount %u",
+		  __get_str(dev), __get_str(kind), __entry->port, __entry->addr,
+		  __entry->vid, __entry->db_buf, __entry->refcount)
+);
+
+/* Bump the refcount of an existing unicast/multicast address on shared ports */
+DEFINE_EVENT(dsa_port_addr_op_refcount, dsa_fdb_add_bump,
+	     TP_PROTO(const struct dsa_port *dp, const unsigned char *addr,
+		      u16 vid, const struct dsa_db *db,
+		      const refcount_t *refcount),
+	     TP_ARGS(dp, addr, vid, db, refcount));
+
+DEFINE_EVENT(dsa_port_addr_op_refcount, dsa_mdb_add_bump,
+	     TP_PROTO(const struct dsa_port *dp, const unsigned char *addr,
+		      u16 vid, const struct dsa_db *db,
+		      const refcount_t *refcount),
+	     TP_ARGS(dp, addr, vid, db, refcount));
+
+/* Drop the refcount of a multicast address that we still keep on
+ * shared ports
+ */
+DEFINE_EVENT(dsa_port_addr_op_refcount, dsa_fdb_del_drop,
+	     TP_PROTO(const struct dsa_port *dp, const unsigned char *addr,
+		      u16 vid, const struct dsa_db *db,
+		      const refcount_t *refcount),
+	     TP_ARGS(dp, addr, vid, db, refcount));
+
+DEFINE_EVENT(dsa_port_addr_op_refcount, dsa_mdb_del_drop,
+	     TP_PROTO(const struct dsa_port *dp, const unsigned char *addr,
+		      u16 vid, const struct dsa_db *db,
+		      const refcount_t *refcount),
+	     TP_ARGS(dp, addr, vid, db, refcount));
+
+DECLARE_EVENT_CLASS(dsa_port_addr_del_not_found,
+
+	TP_PROTO(const struct dsa_port *dp, const unsigned char *addr, u16 vid,
+		 const struct dsa_db *db),
+
+	TP_ARGS(dp, addr, vid, db),
+
+	TP_STRUCT__entry(
+		__string(dev, dev_name(dp->ds->dev))
+		__string(kind, dsa_port_kind(dp))
+		__field(int, port)
+		__array(unsigned char, addr, ETH_ALEN)
+		__field(u16, vid)
+		__array(char, db_buf, DSA_DB_BUFSIZ)
+	),
+
+	TP_fast_assign(
+		__assign_str(dev);
+		__assign_str(kind);
+		__entry->port = dp->index;
+		ether_addr_copy(__entry->addr, addr);
+		__entry->vid = vid;
+		dsa_db_print(db, __entry->db_buf);
+	),
+
+	TP_printk("%s %s port %d addr %pM vid %u db \"%s\"",
+		  __get_str(dev), __get_str(kind), __entry->port,
+		  __entry->addr, __entry->vid, __entry->db_buf)
+);
+
+/* Attempt to delete a unicast/multicast address on shared ports for which
+ * the delete operation was called more times than the addition
+ */
+DEFINE_EVENT(dsa_port_addr_del_not_found, dsa_fdb_del_not_found,
+	     TP_PROTO(const struct dsa_port *dp, const unsigned char *addr,
+		      u16 vid, const struct dsa_db *db),
+	     TP_ARGS(dp, addr, vid, db));
+
+DEFINE_EVENT(dsa_port_addr_del_not_found, dsa_mdb_del_not_found,
+	     TP_PROTO(const struct dsa_port *dp, const unsigned char *addr,
+		      u16 vid, const struct dsa_db *db),
+	     TP_ARGS(dp, addr, vid, db));
+
+TRACE_EVENT(dsa_lag_fdb_add_hw,
+
+	TP_PROTO(const struct net_device *lag_dev, const unsigned char *addr,
+		 u16 vid, const struct dsa_db *db, int err),
+
+	TP_ARGS(lag_dev, addr, vid, db, err),
+
+	TP_STRUCT__entry(
+		__string(dev, lag_dev->name)
+		__array(unsigned char, addr, ETH_ALEN)
+		__field(u16, vid)
+		__array(char, db_buf, DSA_DB_BUFSIZ)
+		__field(int, err)
+	),
+
+	TP_fast_assign(
+		__assign_str(dev);
+		ether_addr_copy(__entry->addr, addr);
+		__entry->vid = vid;
+		dsa_db_print(db, __entry->db_buf);
+		__entry->err = err;
+	),
+
+	TP_printk("%s addr %pM vid %u db \"%s\" err %d",
+		  __get_str(dev), __entry->addr, __entry->vid,
+		  __entry->db_buf, __entry->err)
+);
+
+TRACE_EVENT(dsa_lag_fdb_add_bump,
+
+	TP_PROTO(const struct net_device *lag_dev, const unsigned char *addr,
+		 u16 vid, const struct dsa_db *db, const refcount_t *refcount),
+
+	TP_ARGS(lag_dev, addr, vid, db, refcount),
+
+	TP_STRUCT__entry(
+		__string(dev, lag_dev->name)
+		__array(unsigned char, addr, ETH_ALEN)
+		__field(u16, vid)
+		__array(char, db_buf, DSA_DB_BUFSIZ)
+		__field(unsigned int, refcount)
+	),
+
+	TP_fast_assign(
+		__assign_str(dev);
+		ether_addr_copy(__entry->addr, addr);
+		__entry->vid = vid;
+		dsa_db_print(db, __entry->db_buf);
+		__entry->refcount = refcount_read(refcount);
+	),
+
+	TP_printk("%s addr %pM vid %u db \"%s\" refcount %u",
+		  __get_str(dev), __entry->addr, __entry->vid,
+		  __entry->db_buf, __entry->refcount)
+);
+
+TRACE_EVENT(dsa_lag_fdb_del_hw,
+
+	TP_PROTO(const struct net_device *lag_dev, const unsigned char *addr,
+		 u16 vid, const struct dsa_db *db, int err),
+
+	TP_ARGS(lag_dev, addr, vid, db, err),
+
+	TP_STRUCT__entry(
+		__string(dev, lag_dev->name)
+		__array(unsigned char, addr, ETH_ALEN)
+		__field(u16, vid)
+		__array(char, db_buf, DSA_DB_BUFSIZ)
+		__field(int, err)
+	),
+
+	TP_fast_assign(
+		__assign_str(dev);
+		ether_addr_copy(__entry->addr, addr);
+		__entry->vid = vid;
+		dsa_db_print(db, __entry->db_buf);
+		__entry->err = err;
+	),
+
+	TP_printk("%s addr %pM vid %u db \"%s\" err %d",
+		  __get_str(dev), __entry->addr, __entry->vid,
+		  __entry->db_buf, __entry->err)
+);
+
+TRACE_EVENT(dsa_lag_fdb_del_drop,
+
+	TP_PROTO(const struct net_device *lag_dev, const unsigned char *addr,
+		 u16 vid, const struct dsa_db *db, const refcount_t *refcount),
+
+	TP_ARGS(lag_dev, addr, vid, db, refcount),
+
+	TP_STRUCT__entry(
+		__string(dev, lag_dev->name)
+		__array(unsigned char, addr, ETH_ALEN)
+		__field(u16, vid)
+		__array(char, db_buf, DSA_DB_BUFSIZ)
+		__field(unsigned int, refcount)
+	),
+
+	TP_fast_assign(
+		__assign_str(dev);
+		ether_addr_copy(__entry->addr, addr);
+		__entry->vid = vid;
+		dsa_db_print(db, __entry->db_buf);
+		__entry->refcount = refcount_read(refcount);
+	),
+
+	TP_printk("%s addr %pM vid %u db \"%s\" refcount %u",
+		  __get_str(dev), __entry->addr, __entry->vid,
+		  __entry->db_buf, __entry->refcount)
+);
+
+TRACE_EVENT(dsa_lag_fdb_del_not_found,
+
+	TP_PROTO(const struct net_device *lag_dev, const unsigned char *addr,
+		 u16 vid, const struct dsa_db *db),
+
+	TP_ARGS(lag_dev, addr, vid, db),
+
+	TP_STRUCT__entry(
+		__string(dev, lag_dev->name)
+		__array(unsigned char, addr, ETH_ALEN)
+		__field(u16, vid)
+		__array(char, db_buf, DSA_DB_BUFSIZ)
+	),
+
+	TP_fast_assign(
+		__assign_str(dev);
+		ether_addr_copy(__entry->addr, addr);
+		__entry->vid = vid;
+		dsa_db_print(db, __entry->db_buf);
+	),
+
+	TP_printk("%s addr %pM vid %u db \"%s\"",
+		  __get_str(dev), __entry->addr, __entry->vid, __entry->db_buf)
+);
+
+DECLARE_EVENT_CLASS(dsa_vlan_op_hw,
+
+	TP_PROTO(const struct dsa_port *dp,
+		 const struct switchdev_obj_port_vlan *vlan, int err),
+
+	TP_ARGS(dp, vlan, err),
+
+	TP_STRUCT__entry(
+		__string(dev, dev_name(dp->ds->dev))
+		__string(kind, dsa_port_kind(dp))
+		__field(int, port)
+		__field(u16, vid)
+		__field(u16, flags)
+		__field(bool, changed)
+		__field(int, err)
+	),
+
+	TP_fast_assign(
+		__assign_str(dev);
+		__assign_str(kind);
+		__entry->port = dp->index;
+		__entry->vid = vlan->vid;
+		__entry->flags = vlan->flags;
+		__entry->changed = vlan->changed;
+		__entry->err = err;
+	),
+
+	TP_printk("%s %s port %d vid %u%s%s%s",
+		  __get_str(dev), __get_str(kind), __entry->port, __entry->vid,
+		  __entry->flags & BRIDGE_VLAN_INFO_PVID ? " pvid" : "",
+		  __entry->flags & BRIDGE_VLAN_INFO_UNTAGGED ? " untagged" : "",
+		  __entry->changed ? " (changed)" : "")
+);
+
+DEFINE_EVENT(dsa_vlan_op_hw, dsa_vlan_add_hw,
+	     TP_PROTO(const struct dsa_port *dp,
+		      const struct switchdev_obj_port_vlan *vlan, int err),
+	     TP_ARGS(dp, vlan, err));
+
+DEFINE_EVENT(dsa_vlan_op_hw, dsa_vlan_del_hw,
+	     TP_PROTO(const struct dsa_port *dp,
+		      const struct switchdev_obj_port_vlan *vlan, int err),
+	     TP_ARGS(dp, vlan, err));
+
+DECLARE_EVENT_CLASS(dsa_vlan_op_refcount,
+
+	TP_PROTO(const struct dsa_port *dp,
+		 const struct switchdev_obj_port_vlan *vlan,
+		 const refcount_t *refcount),
+
+	TP_ARGS(dp, vlan, refcount),
+
+	TP_STRUCT__entry(
+		__string(dev, dev_name(dp->ds->dev))
+		__string(kind, dsa_port_kind(dp))
+		__field(int, port)
+		__field(u16, vid)
+		__field(u16, flags)
+		__field(bool, changed)
+		__field(unsigned int, refcount)
+	),
+
+	TP_fast_assign(
+		__assign_str(dev);
+		__assign_str(kind);
+		__entry->port = dp->index;
+		__entry->vid = vlan->vid;
+		__entry->flags = vlan->flags;
+		__entry->changed = vlan->changed;
+		__entry->refcount = refcount_read(refcount);
+	),
+
+	TP_printk("%s %s port %d vid %u%s%s%s refcount %u",
+		  __get_str(dev), __get_str(kind), __entry->port, __entry->vid,
+		  __entry->flags & BRIDGE_VLAN_INFO_PVID ? " pvid" : "",
+		  __entry->flags & BRIDGE_VLAN_INFO_UNTAGGED ? " untagged" : "",
+		  __entry->changed ? " (changed)" : "", __entry->refcount)
+);
+
+DEFINE_EVENT(dsa_vlan_op_refcount, dsa_vlan_add_bump,
+	     TP_PROTO(const struct dsa_port *dp,
+		      const struct switchdev_obj_port_vlan *vlan,
+		      const refcount_t *refcount),
+	     TP_ARGS(dp, vlan, refcount));
+
+DEFINE_EVENT(dsa_vlan_op_refcount, dsa_vlan_del_drop,
+	     TP_PROTO(const struct dsa_port *dp,
+		      const struct switchdev_obj_port_vlan *vlan,
+		      const refcount_t *refcount),
+	     TP_ARGS(dp, vlan, refcount));
+
+TRACE_EVENT(dsa_vlan_del_not_found,
+
+	TP_PROTO(const struct dsa_port *dp,
+		 const struct switchdev_obj_port_vlan *vlan),
+
+	TP_ARGS(dp, vlan),
+
+	TP_STRUCT__entry(
+		__string(dev, dev_name(dp->ds->dev))
+		__string(kind, dsa_port_kind(dp))
+		__field(int, port)
+		__field(u16, vid)
+	),
+
+	TP_fast_assign(
+		__assign_str(dev);
+		__assign_str(kind);
+		__entry->port = dp->index;
+		__entry->vid = vlan->vid;
+	),
+
+	TP_printk("%s %s port %d vid %u",
+		  __get_str(dev), __get_str(kind), __entry->port, __entry->vid)
+);
+
+#endif /* _NET_DSA_TRACE_H */
+
+/* We don't want to use include/trace/events */
+#undef TRACE_INCLUDE_PATH
+#define TRACE_INCLUDE_PATH .
+#undef TRACE_INCLUDE_FILE
+#define TRACE_INCLUDE_FILE	trace
+/* This part must be outside protection */
+#include <trace/define_trace.h>