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, 135 insertions, 0 deletions

diff --git a/scripts/sbom/sbom.py b/scripts/sbom/sbom.py
new file mode 100644
index 000000000..764175b9c
--- /dev/null
+++ b/scripts/sbom/sbom.py
@@ -0,0 +1,135 @@
+#!/usr/bin/env python3
+# SPDX-License-Identifier: GPL-2.0-only OR MIT
+# Copyright (C) 2025 TNG Technology Consulting GmbH
+
+"""
+Compute software bill of materials in SPDX format describing a kernel build.
+"""
+
+import json
+import logging
+import os
+import sys
+import time
+import uuid
+import sbom.sbom_logging as sbom_logging
+from sbom.config import get_config
+from sbom.path_utils import is_relative_to
+from sbom.spdx import JsonLdSpdxDocument, SpdxIdGenerator
+from sbom.spdx.core import CreationInfo, SpdxDocument
+from sbom.spdx_graph import SpdxIdGeneratorCollection, build_spdx_graphs
+from sbom.cmd_graph import CmdGraph
+
+
+def _exit_with_summary(write_output_on_error: bool = False) -> None:
+    warning_summary = sbom_logging.summarize_warnings()
+    error_summary = sbom_logging.summarize_errors()
+    if warning_summary:
+        logging.warning(warning_summary)
+    if error_summary:
+        logging.error(error_summary)
+        if not write_output_on_error:
+            logging.info(
+                "Use --write-output-on-error to generate output documents even when errors occur. "
+                "Note that in this case the generated documents may be incomplete."
+            )
+        sys.exit(1)
+
+
+def main():
+    # Read config
+    config = get_config()
+
+    # Configure logging
+    logging.basicConfig(
+        level=logging.DEBUG if config.debug else logging.INFO,
+        format="[%(levelname)s] %(message)s",
+    )
+
+    # Build cmd graph
+    logging.debug("Start building cmd graph")
+    start_time = time.time()
+    cmd_graph = CmdGraph.create(config.root_paths, config)
+    logging.debug(f"Built cmd graph in {time.time() - start_time} seconds")
+
+    # Save used files document
+    if config.generate_used_files:
+        if config.src_tree == config.obj_tree:
+            logging.info(
+                f"Extracting all files from the cmd graph to {config.used_files_file_name} "
+                "instead of only source files because source files cannot be "
+                "reliably classified when the source and object trees are identical.",
+            )
+            used_files = [os.path.relpath(node.absolute_path, config.src_tree) for node in cmd_graph]
+            logging.debug(f"Found {len(used_files)} files in cmd graph.")
+        else:
+            used_files = [
+                os.path.relpath(node.absolute_path, config.src_tree)
+                for node in cmd_graph
+                if is_relative_to(node.absolute_path, config.src_tree)
+                and not is_relative_to(node.absolute_path, config.obj_tree)
+            ]
+            logging.debug(f"Found {len(used_files)} source files in cmd graph")
+        if not sbom_logging.has_errors() or config.write_output_on_error:
+            used_files_path = os.path.join(config.output_directory, config.used_files_file_name)
+            with open(used_files_path, "w", encoding="utf-8") as f:
+                f.write("\n".join(str(file_path) for file_path in used_files))
+            logging.debug(f"Successfully saved {used_files_path}")
+
+    if config.generate_spdx is False:
+        _exit_with_summary(config.write_output_on_error)
+        return
+
+    # Build SPDX Documents
+    logging.debug("Start generating SPDX graph based on cmd graph")
+    start_time = time.time()
+
+    # The real uuid will be generated based on the content of the SPDX graphs
+    # to ensure that the same SPDX document is always assigned the same uuid.
+    PLACEHOLDER_UUID = "00000000-0000-0000-0000-000000000000"
+    spdx_id_base_namespace = f"{config.spdxId_prefix}{PLACEHOLDER_UUID}/"
+    spdx_id_generators = SpdxIdGeneratorCollection(
+        base=SpdxIdGenerator(prefix="p", namespace=spdx_id_base_namespace),
+        source=SpdxIdGenerator(prefix="s", namespace=f"{spdx_id_base_namespace}source/"),
+        build=SpdxIdGenerator(prefix="b", namespace=f"{spdx_id_base_namespace}build/"),
+        output=SpdxIdGenerator(prefix="o", namespace=f"{spdx_id_base_namespace}output/"),
+    )
+
+    spdx_graphs = build_spdx_graphs(
+        cmd_graph,
+        spdx_id_generators,
+        config,
+    )
+    spdx_id_uuid = uuid.uuid5(
+        uuid.NAMESPACE_URL,
+        "".join(
+            json.dumps(element.to_dict()) for spdx_graph in spdx_graphs.values() for element in spdx_graph.to_list()
+        ),
+    )
+    logging.debug(f"Generated SPDX graph in {time.time() - start_time} seconds")
+
+    if not sbom_logging.has_errors() or config.write_output_on_error:
+        for kernel_sbom_kind, spdx_graph in spdx_graphs.items():
+            spdx_graph_objects = spdx_graph.to_list()
+            # Add warning and error summary to creation info comment
+            creation_info = next(element for element in spdx_graph_objects if isinstance(element, CreationInfo))
+            creation_info.comment = "\n".join([
+                sbom_logging.summarize_warnings(),
+                sbom_logging.summarize_errors(),
+            ]).strip()
+            # Replace Placeholder uuid with real uuid for spdxIds
+            spdx_document = next(element for element in spdx_graph_objects if isinstance(element, SpdxDocument))
+            for namespaceMap in spdx_document.namespaceMap:
+                namespaceMap.namespace = namespaceMap.namespace.replace(PLACEHOLDER_UUID, str(spdx_id_uuid))
+            # Serialize SPDX graph to JSON-LD
+            spdx_doc = JsonLdSpdxDocument(graph=spdx_graph_objects)
+            save_path = os.path.join(config.output_directory, config.spdx_file_names[kernel_sbom_kind])
+            spdx_doc.save(save_path, config.prettify_json)
+            logging.debug(f"Successfully saved {save_path}")
+
+    _exit_with_summary(config.write_output_on_error)
+
+
+# Call main method
+if __name__ == "__main__":
+    main()