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, 77 insertions, 0 deletions

diff --git a/drivers/net/team/Kconfig b/drivers/net/team/Kconfig
new file mode 100644
index 000000000..4d449845d
--- /dev/null
+++ b/drivers/net/team/Kconfig
@@ -0,0 +1,77 @@
+# SPDX-License-Identifier: GPL-2.0-only
+menuconfig NET_TEAM
+	tristate "Ethernet team driver support"
+	help
+	  This allows one to create virtual interfaces that teams together
+	  multiple ethernet devices.
+
+	  Team devices can be added using the "ip" command from the
+	  iproute2 package:
+
+	  "ip link add link [ address MAC ] [ NAME ] type team"
+
+	  To compile this driver as a module, choose M here: the module
+	  will be called team.
+
+if NET_TEAM
+
+config NET_TEAM_MODE_BROADCAST
+	tristate "Broadcast mode support"
+	depends on NET_TEAM
+	help
+	  Basic mode where packets are transmitted always by all suitable ports.
+
+	  All added ports are setup to have team's device address.
+
+	  To compile this team mode as a module, choose M here: the module
+	  will be called team_mode_broadcast.
+
+config NET_TEAM_MODE_ROUNDROBIN
+	tristate "Round-robin mode support"
+	depends on NET_TEAM
+	help
+	  Basic mode where port used for transmitting packets is selected in
+	  round-robin fashion using packet counter.
+
+	  All added ports are setup to have team's device address.
+
+	  To compile this team mode as a module, choose M here: the module
+	  will be called team_mode_roundrobin.
+
+config NET_TEAM_MODE_RANDOM
+	tristate "Random mode support"
+	depends on NET_TEAM
+	help
+	  Basic mode where port used for transmitting packets is selected
+	  randomly.
+
+	  All added ports are setup to have team's device address.
+
+	  To compile this team mode as a module, choose M here: the module
+	  will be called team_mode_random.
+
+config NET_TEAM_MODE_ACTIVEBACKUP
+	tristate "Active-backup mode support"
+	depends on NET_TEAM
+	help
+	  Only one port is active at a time and the rest of ports are used
+	  for backup.
+
+	  Mac addresses of ports are not modified. Userspace is responsible
+	  to do so.
+
+	  To compile this team mode as a module, choose M here: the module
+	  will be called team_mode_activebackup.
+
+config NET_TEAM_MODE_LOADBALANCE
+	tristate "Load-balance mode support"
+	depends on NET_TEAM
+	help
+	  This mode provides load balancing functionality. Tx port selection
+	  is done using BPF function set up from userspace (bpf_hash_func
+	  option)
+
+	  To compile this team mode as a module, choose M here: the module
+	  will be called team_mode_loadbalance.
+
+endif # NET_TEAM