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, 190 insertions, 0 deletions

diff --git a/sound/soc/sof/loader.c b/sound/soc/sof/loader.c
new file mode 100644
index 000000000..0baf316b0
--- /dev/null
+++ b/sound/soc/sof/loader.c
@@ -0,0 +1,190 @@
+// SPDX-License-Identifier: (GPL-2.0-only OR BSD-3-Clause)
+//
+// This file is provided under a dual BSD/GPLv2 license.  When using or
+// redistributing this file, you may do so under either license.
+//
+// Copyright(c) 2018 Intel Corporation
+//
+// Author: Liam Girdwood <liam.r.girdwood@linux.intel.com>
+//
+// Generic firmware loader.
+//
+
+#include <linux/firmware.h>
+#include "sof-priv.h"
+#include "ops.h"
+
+int snd_sof_load_firmware_raw(struct snd_sof_dev *sdev)
+{
+	struct snd_sof_pdata *plat_data = sdev->pdata;
+	const char *fw_filename;
+	ssize_t ext_man_size;
+	int ret;
+
+	/* Don't request firmware again if firmware is already requested */
+	if (sdev->basefw.fw)
+		return 0;
+
+	fw_filename = kasprintf(GFP_KERNEL, "%s/%s",
+				plat_data->fw_filename_prefix,
+				plat_data->fw_filename);
+	if (!fw_filename)
+		return -ENOMEM;
+
+	ret = request_firmware(&sdev->basefw.fw, fw_filename, sdev->dev);
+
+	if (ret < 0) {
+		dev_err(sdev->dev,
+			"error: sof firmware file is missing, you might need to\n");
+		dev_err(sdev->dev,
+			"       download it from https://github.com/thesofproject/sof-bin/\n");
+		goto err;
+	} else {
+		dev_dbg(sdev->dev, "request_firmware %s successful\n",
+			fw_filename);
+	}
+
+	/* check for extended manifest */
+	ext_man_size = sdev->ipc->ops->fw_loader->parse_ext_manifest(sdev);
+	if (ext_man_size > 0) {
+		/* when no error occurred, drop extended manifest */
+		sdev->basefw.payload_offset = ext_man_size;
+	} else if (!ext_man_size) {
+		/* No extended manifest, so nothing to skip during FW load */
+		dev_dbg(sdev->dev, "firmware doesn't contain extended manifest\n");
+	} else {
+		ret = ext_man_size;
+		dev_err(sdev->dev, "error: firmware %s contains unsupported or invalid extended manifest: %d\n",
+			fw_filename, ret);
+	}
+
+err:
+	kfree(fw_filename);
+
+	return ret;
+}
+EXPORT_SYMBOL(snd_sof_load_firmware_raw);
+
+int snd_sof_load_firmware_memcpy(struct snd_sof_dev *sdev)
+{
+	int ret;
+
+	ret = snd_sof_load_firmware_raw(sdev);
+	if (ret < 0)
+		return ret;
+
+	/* make sure the FW header and file is valid */
+	ret = sdev->ipc->ops->fw_loader->validate(sdev);
+	if (ret < 0) {
+		dev_err(sdev->dev, "error: invalid FW header\n");
+		goto error;
+	}
+
+	/* prepare the DSP for FW loading */
+	ret = snd_sof_dsp_reset(sdev);
+	if (ret < 0) {
+		dev_err(sdev->dev, "error: failed to reset DSP\n");
+		goto error;
+	}
+
+	/* parse and load firmware modules to DSP */
+	if (sdev->ipc->ops->fw_loader->load_fw_to_dsp) {
+		ret = sdev->ipc->ops->fw_loader->load_fw_to_dsp(sdev);
+		if (ret < 0) {
+			dev_err(sdev->dev, "Firmware loading failed\n");
+			goto error;
+		}
+	}
+
+	return 0;
+
+error:
+	release_firmware(sdev->basefw.fw);
+	sdev->basefw.fw = NULL;
+	return ret;
+
+}
+EXPORT_SYMBOL(snd_sof_load_firmware_memcpy);
+
+int snd_sof_run_firmware(struct snd_sof_dev *sdev)
+{
+	int ret;
+
+	init_waitqueue_head(&sdev->boot_wait);
+
+	/* (re-)enable dsp dump */
+	sdev->dbg_dump_printed = false;
+	sdev->ipc_dump_printed = false;
+
+	/* create read-only fw_version debugfs to store boot version info */
+	if (sdev->first_boot) {
+		ret = snd_sof_debugfs_buf_item(sdev, &sdev->fw_version,
+					       sizeof(sdev->fw_version),
+					       "fw_version", 0444);
+		/* errors are only due to memory allocation, not debugfs */
+		if (ret < 0) {
+			dev_err(sdev->dev, "snd_sof_debugfs_buf_item failed\n");
+			return ret;
+		}
+	}
+
+	/* perform pre fw run operations */
+	ret = snd_sof_dsp_pre_fw_run(sdev);
+	if (ret < 0) {
+		dev_err(sdev->dev, "failed pre fw run op\n");
+		return ret;
+	}
+
+	dev_dbg(sdev->dev, "booting DSP firmware\n");
+
+	/* boot the firmware on the DSP */
+	ret = snd_sof_dsp_run(sdev);
+	if (ret < 0) {
+		snd_sof_dsp_dbg_dump(sdev, "Failed to start DSP",
+				     SOF_DBG_DUMP_MBOX | SOF_DBG_DUMP_PCI);
+		return ret;
+	}
+
+	/*
+	 * now wait for the DSP to boot. There are 3 possible outcomes:
+	 * 1. Boot wait times out indicating FW boot failure.
+	 * 2. FW boots successfully and fw_ready op succeeds.
+	 * 3. FW boots but fw_ready op fails.
+	 */
+	ret = wait_event_timeout(sdev->boot_wait,
+				 sdev->fw_state > SOF_FW_BOOT_IN_PROGRESS,
+				 msecs_to_jiffies(sdev->boot_timeout));
+	if (ret == 0) {
+		snd_sof_dsp_dbg_dump(sdev, "Firmware boot failure due to timeout",
+				     SOF_DBG_DUMP_REGS | SOF_DBG_DUMP_MBOX |
+				     SOF_DBG_DUMP_TEXT | SOF_DBG_DUMP_PCI);
+		return -EIO;
+	}
+
+	if (sdev->fw_state == SOF_FW_BOOT_READY_FAILED)
+		return -EIO; /* FW boots but fw_ready op failed */
+
+	dev_dbg(sdev->dev, "firmware boot complete\n");
+	sof_set_fw_state(sdev, SOF_FW_BOOT_COMPLETE);
+
+	/* perform post fw run operations */
+	ret = snd_sof_dsp_post_fw_run(sdev);
+	if (ret < 0) {
+		dev_err(sdev->dev, "error: failed post fw run op\n");
+		return ret;
+	}
+
+	if (sdev->ipc->ops->post_fw_boot)
+		return sdev->ipc->ops->post_fw_boot(sdev);
+
+	return 0;
+}
+EXPORT_SYMBOL(snd_sof_run_firmware);
+
+void snd_sof_fw_unload(struct snd_sof_dev *sdev)
+{
+	/* TODO: support module unloading at runtime */
+	release_firmware(sdev->basefw.fw);
+	sdev->basefw.fw = NULL;
+}
+EXPORT_SYMBOL(snd_sof_fw_unload);