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, 160 insertions, 0 deletions

diff --git a/net/xfrm/Kconfig b/net/xfrm/Kconfig
new file mode 100644
index 000000000..4a62817a8
--- /dev/null
+++ b/net/xfrm/Kconfig
@@ -0,0 +1,160 @@
+# SPDX-License-Identifier: GPL-2.0-only
+#
+# XFRM configuration
+#
+config XFRM
+	bool
+	depends on INET
+	select GRO_CELLS
+	select SKB_EXTENSIONS
+
+config XFRM_OFFLOAD
+	bool
+
+config XFRM_ALGO
+	tristate
+	select XFRM
+	select CRYPTO
+	select CRYPTO_AEAD
+	select CRYPTO_HASH
+	select CRYPTO_SKCIPHER
+
+if INET
+config XFRM_USER
+	tristate "Transformation user configuration interface"
+	select XFRM_ALGO
+	help
+	  Support for Transformation(XFRM) user configuration interface
+	  like IPsec used by native Linux tools.
+
+	  If unsure, say Y.
+
+config XFRM_USER_COMPAT
+	tristate "Compatible ABI support"
+	depends on XFRM_USER && COMPAT_FOR_U64_ALIGNMENT && \
+		HAVE_EFFICIENT_UNALIGNED_ACCESS
+	select WANT_COMPAT_NETLINK_MESSAGES
+	help
+	  Transformation(XFRM) user configuration interface like IPsec
+	  used by compatible Linux applications.
+
+	  If unsure, say N.
+
+config XFRM_INTERFACE
+	tristate "Transformation virtual interface"
+	depends on XFRM && IPV6
+	help
+	  This provides a virtual interface to route IPsec traffic.
+
+	  If unsure, say N.
+
+config XFRM_SUB_POLICY
+	bool "Transformation sub policy support"
+	depends on XFRM
+	help
+	  Support sub policy for developers. By using sub policy with main
+	  one, two policies can be applied to the same packet at once.
+	  Policy which lives shorter time in kernel should be a sub.
+
+	  If unsure, say N.
+
+config XFRM_MIGRATE
+	bool "Transformation migrate database"
+	depends on XFRM
+	help
+	  A feature to update locator(s) of a given IPsec security
+	  association dynamically.  This feature is required, for
+	  instance, in a Mobile IPv6 environment with IPsec configuration
+	  where mobile nodes change their attachment point to the Internet.
+
+	  If unsure, say N.
+
+config XFRM_STATISTICS
+	bool "Transformation statistics"
+	depends on XFRM && PROC_FS
+	help
+	  This statistics is not a SNMP/MIB specification but shows
+	  statistics about transformation error (or almost error) factor
+	  at packet processing for developer.
+
+	  If unsure, say N.
+
+# This option selects XFRM_ALGO along with the AH authentication algorithms that
+# RFC 8221 lists as MUST be implemented.
+config XFRM_AH
+	tristate
+	select XFRM_ALGO
+	select CRYPTO
+	select CRYPTO_HMAC
+	select CRYPTO_SHA256
+
+# This option selects XFRM_ALGO along with the ESP encryption and authentication
+# algorithms that RFC 8221 lists as MUST be implemented.
+config XFRM_ESP
+	tristate
+	select XFRM_ALGO
+	select CRYPTO
+	select CRYPTO_AES
+	select CRYPTO_AUTHENC
+	select CRYPTO_CBC
+	select CRYPTO_ECHAINIV
+	select CRYPTO_GCM
+	select CRYPTO_HMAC
+	select CRYPTO_SEQIV
+	select CRYPTO_SHA256
+
+config XFRM_IPCOMP
+	tristate
+	select XFRM_ALGO
+	select CRYPTO
+	select CRYPTO_DEFLATE
+
+config NET_KEY
+	tristate "PF_KEY sockets (deprecated)"
+	select XFRM_ALGO
+	help
+	  PF_KEYv2 socket family, compatible to KAME ones.
+
+	  The PF_KEYv2 socket interface is deprecated and
+	  scheduled for removal. All maintained IKE daemons
+	  no longer need PF_KEY sockets. Please use the netlink
+	  interface (XFRM_USER) to configure IPsec.
+
+	  If unsure, say N.
+
+config NET_KEY_MIGRATE
+	bool "PF_KEY MIGRATE"
+	depends on NET_KEY
+	select XFRM_MIGRATE
+	help
+	  Add a PF_KEY MIGRATE message to PF_KEYv2 socket family.
+	  The PF_KEY MIGRATE message is used to dynamically update
+	  locator(s) of a given IPsec security association.
+	  This feature is required, for instance, in a Mobile IPv6
+	  environment with IPsec configuration where mobile nodes
+	  change their attachment point to the Internet.  Detail
+	  information can be found in the internet-draft
+	  <draft-sugimoto-mip6-pfkey-migrate>.
+
+	  If unsure, say N.
+
+config XFRM_IPTFS
+	tristate "IPsec IP-TFS/AGGFRAG (RFC 9347) encapsulation support"
+	depends on XFRM
+	help
+	  Information on the IP-TFS/AGGFRAG encapsulation can be found
+	  in RFC 9347. This feature supports demand driven (i.e.,
+	  non-constant send rate) IP-TFS to take advantage of the
+	  AGGFRAG ESP payload encapsulation. This payload type
+	  supports aggregation and fragmentation of the inner IP
+	  packet stream which in turn yields higher small-packet
+	  bandwidth as well as reducing MTU/PMTU issues. Congestion
+	  control is unimplementated as the send rate is demand driven
+	  rather than constant.
+
+	  If unsure, say N.
+
+config XFRM_ESPINTCP
+	bool
+
+endif # INET