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, 438 insertions, 0 deletions

diff --git a/drivers/scsi/scsi_logging.c b/drivers/scsi/scsi_logging.c
new file mode 100644
index 000000000..3cd0d3074
--- /dev/null
+++ b/drivers/scsi/scsi_logging.c
@@ -0,0 +1,438 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * scsi_logging.c
+ *
+ * Copyright (C) 2014 SUSE Linux Products GmbH
+ * Copyright (C) 2014 Hannes Reinecke <hare@suse.de>
+ */
+
+#include <linux/kernel.h>
+#include <linux/atomic.h>
+
+#include <scsi/scsi.h>
+#include <scsi/scsi_cmnd.h>
+#include <scsi/scsi_device.h>
+#include <scsi/scsi_eh.h>
+#include <scsi/scsi_dbg.h>
+
+static char *scsi_log_reserve_buffer(size_t *len)
+{
+	*len = 128;
+	return kmalloc(*len, GFP_ATOMIC);
+}
+
+static void scsi_log_release_buffer(char *bufptr)
+{
+	kfree(bufptr);
+}
+
+static inline const char *scmd_name(struct scsi_cmnd *scmd)
+{
+	const struct request *rq = scsi_cmd_to_rq(scmd);
+
+	if (!rq->q || !rq->q->disk)
+		return NULL;
+	return rq->q->disk->disk_name;
+}
+
+static size_t sdev_format_header(char *logbuf, size_t logbuf_len,
+				 const char *name, int tag)
+{
+	size_t off = 0;
+
+	if (name)
+		off += scnprintf(logbuf + off, logbuf_len - off,
+				 "[%s] ", name);
+
+	if (WARN_ON(off >= logbuf_len))
+		return off;
+
+	if (tag >= 0)
+		off += scnprintf(logbuf + off, logbuf_len - off,
+				 "tag#%d ", tag);
+	return off;
+}
+
+void sdev_prefix_printk(const char *level, const struct scsi_device *sdev,
+			const char *name, const char *fmt, ...)
+{
+	va_list args;
+	char *logbuf;
+	size_t off = 0, logbuf_len;
+
+	if (!sdev)
+		return;
+
+	logbuf = scsi_log_reserve_buffer(&logbuf_len);
+	if (!logbuf)
+		return;
+
+	if (name)
+		off += scnprintf(logbuf + off, logbuf_len - off,
+				 "[%s] ", name);
+	if (!WARN_ON(off >= logbuf_len)) {
+		va_start(args, fmt);
+		off += vscnprintf(logbuf + off, logbuf_len - off, fmt, args);
+		va_end(args);
+	}
+	dev_printk(level, &sdev->sdev_gendev, "%s", logbuf);
+	scsi_log_release_buffer(logbuf);
+}
+EXPORT_SYMBOL(sdev_prefix_printk);
+
+void scmd_printk(const char *level, struct scsi_cmnd *scmd, const char *fmt,
+		 ...)
+{
+	va_list args;
+	char *logbuf;
+	size_t off = 0, logbuf_len;
+
+	if (!scmd)
+		return;
+
+	logbuf = scsi_log_reserve_buffer(&logbuf_len);
+	if (!logbuf)
+		return;
+	off = sdev_format_header(logbuf, logbuf_len, scmd_name(scmd),
+				 scsi_cmd_to_rq(scmd)->tag);
+	if (off < logbuf_len) {
+		va_start(args, fmt);
+		off += vscnprintf(logbuf + off, logbuf_len - off, fmt, args);
+		va_end(args);
+	}
+	dev_printk(level, &scmd->device->sdev_gendev, "%s", logbuf);
+	scsi_log_release_buffer(logbuf);
+}
+EXPORT_SYMBOL(scmd_printk);
+
+static size_t scsi_format_opcode_name(char *buffer, size_t buf_len,
+				      const unsigned char *cdbp)
+{
+	int sa, cdb0;
+	const char *cdb_name = NULL, *sa_name = NULL;
+	size_t off;
+
+	cdb0 = cdbp[0];
+	if (cdb0 == VARIABLE_LENGTH_CMD) {
+		int len = scsi_varlen_cdb_length(cdbp);
+
+		if (len < 10) {
+			off = scnprintf(buffer, buf_len,
+					"short variable length command, len=%d",
+					len);
+			return off;
+		}
+		sa = (cdbp[8] << 8) + cdbp[9];
+	} else
+		sa = cdbp[1] & 0x1f;
+
+	if (!scsi_opcode_sa_name(cdb0, sa, &cdb_name, &sa_name)) {
+		if (cdb_name)
+			off = scnprintf(buffer, buf_len, "%s", cdb_name);
+		else {
+			off = scnprintf(buffer, buf_len, "opcode=0x%x", cdb0);
+			if (WARN_ON(off >= buf_len))
+				return off;
+			if (cdb0 >= VENDOR_SPECIFIC_CDB)
+				off += scnprintf(buffer + off, buf_len - off,
+						 " (vendor)");
+			else if (cdb0 >= 0x60 && cdb0 < 0x7e)
+				off += scnprintf(buffer + off, buf_len - off,
+						 " (reserved)");
+		}
+	} else {
+		if (sa_name)
+			off = scnprintf(buffer, buf_len, "%s", sa_name);
+		else if (cdb_name)
+			off = scnprintf(buffer, buf_len, "%s, sa=0x%x",
+					cdb_name, sa);
+		else
+			off = scnprintf(buffer, buf_len,
+					"opcode=0x%x, sa=0x%x", cdb0, sa);
+	}
+	WARN_ON(off >= buf_len);
+	return off;
+}
+
+size_t __scsi_format_command(char *logbuf, size_t logbuf_len,
+			     const unsigned char *cdb, size_t cdb_len)
+{
+	int len, k;
+	size_t off;
+
+	off = scsi_format_opcode_name(logbuf, logbuf_len, cdb);
+	if (off >= logbuf_len)
+		return off;
+	len = scsi_command_size(cdb);
+	if (cdb_len < len)
+		len = cdb_len;
+	/* print out all bytes in cdb */
+	for (k = 0; k < len; ++k) {
+		if (off > logbuf_len - 3)
+			break;
+		off += scnprintf(logbuf + off, logbuf_len - off,
+				 " %02x", cdb[k]);
+	}
+	return off;
+}
+EXPORT_SYMBOL(__scsi_format_command);
+
+void scsi_print_command(struct scsi_cmnd *cmd)
+{
+	int k;
+	char *logbuf;
+	size_t off, logbuf_len;
+
+	logbuf = scsi_log_reserve_buffer(&logbuf_len);
+	if (!logbuf)
+		return;
+
+	off = sdev_format_header(logbuf, logbuf_len,
+				 scmd_name(cmd), scsi_cmd_to_rq(cmd)->tag);
+	if (off >= logbuf_len)
+		goto out_printk;
+	off += scnprintf(logbuf + off, logbuf_len - off, "CDB: ");
+	if (WARN_ON(off >= logbuf_len))
+		goto out_printk;
+
+	off += scsi_format_opcode_name(logbuf + off, logbuf_len - off,
+				       cmd->cmnd);
+	if (off >= logbuf_len)
+		goto out_printk;
+
+	/* print out all bytes in cdb */
+	if (cmd->cmd_len > 16) {
+		/* Print opcode in one line and use separate lines for CDB */
+		off += scnprintf(logbuf + off, logbuf_len - off, "\n");
+		dev_printk(KERN_INFO, &cmd->device->sdev_gendev, "%s", logbuf);
+		for (k = 0; k < cmd->cmd_len; k += 16) {
+			size_t linelen = min(cmd->cmd_len - k, 16);
+
+			off = sdev_format_header(logbuf, logbuf_len,
+						 scmd_name(cmd),
+						 scsi_cmd_to_rq(cmd)->tag);
+			if (!WARN_ON(off > logbuf_len - 58)) {
+				off += scnprintf(logbuf + off, logbuf_len - off,
+						 "CDB[%02x]: ", k);
+				hex_dump_to_buffer(&cmd->cmnd[k], linelen,
+						   16, 1, logbuf + off,
+						   logbuf_len - off, false);
+			}
+			dev_printk(KERN_INFO, &cmd->device->sdev_gendev, "%s",
+				   logbuf);
+		}
+		goto out;
+	}
+	if (!WARN_ON(off > logbuf_len - 49)) {
+		off += scnprintf(logbuf + off, logbuf_len - off, " ");
+		hex_dump_to_buffer(cmd->cmnd, cmd->cmd_len, 16, 1,
+				   logbuf + off, logbuf_len - off,
+				   false);
+	}
+out_printk:
+	dev_printk(KERN_INFO, &cmd->device->sdev_gendev, "%s", logbuf);
+out:
+	scsi_log_release_buffer(logbuf);
+}
+EXPORT_SYMBOL(scsi_print_command);
+
+static size_t
+scsi_format_extd_sense(char *buffer, size_t buf_len,
+		       unsigned char asc, unsigned char ascq)
+{
+	size_t off = 0;
+	const char *extd_sense_fmt = NULL;
+	const char *extd_sense_str = scsi_extd_sense_format(asc, ascq,
+							    &extd_sense_fmt);
+
+	if (extd_sense_str) {
+		off = scnprintf(buffer, buf_len, "Add. Sense: %s",
+				extd_sense_str);
+		if (extd_sense_fmt)
+			off += scnprintf(buffer + off, buf_len - off,
+					 "(%s%x)", extd_sense_fmt, ascq);
+	} else {
+		if (asc >= 0x80)
+			off = scnprintf(buffer, buf_len, "<<vendor>>");
+		off += scnprintf(buffer + off, buf_len - off,
+				 "ASC=0x%x ", asc);
+		if (ascq >= 0x80)
+			off += scnprintf(buffer + off, buf_len - off,
+					 "<<vendor>>");
+		off += scnprintf(buffer + off, buf_len - off,
+				 "ASCQ=0x%x ", ascq);
+	}
+	return off;
+}
+
+static size_t
+scsi_format_sense_hdr(char *buffer, size_t buf_len,
+		      const struct scsi_sense_hdr *sshdr)
+{
+	const char *sense_txt;
+	size_t off;
+
+	off = scnprintf(buffer, buf_len, "Sense Key : ");
+	sense_txt = scsi_sense_key_string(sshdr->sense_key);
+	if (sense_txt)
+		off += scnprintf(buffer + off, buf_len - off,
+				 "%s ", sense_txt);
+	else
+		off += scnprintf(buffer + off, buf_len - off,
+				 "0x%x ", sshdr->sense_key);
+	off += scnprintf(buffer + off, buf_len - off,
+		scsi_sense_is_deferred(sshdr) ? "[deferred] " : "[current] ");
+
+	if (sshdr->response_code >= 0x72)
+		off += scnprintf(buffer + off, buf_len - off, "[descriptor] ");
+	return off;
+}
+
+static void
+scsi_log_dump_sense(const struct scsi_device *sdev, const char *name, int tag,
+		    const unsigned char *sense_buffer, int sense_len)
+{
+	char *logbuf;
+	size_t logbuf_len;
+	int i;
+
+	logbuf = scsi_log_reserve_buffer(&logbuf_len);
+	if (!logbuf)
+		return;
+
+	for (i = 0; i < sense_len; i += 16) {
+		int len = min(sense_len - i, 16);
+		size_t off;
+
+		off = sdev_format_header(logbuf, logbuf_len,
+					 name, tag);
+		hex_dump_to_buffer(&sense_buffer[i], len, 16, 1,
+				   logbuf + off, logbuf_len - off,
+				   false);
+		dev_printk(KERN_INFO, &sdev->sdev_gendev, "%s", logbuf);
+	}
+	scsi_log_release_buffer(logbuf);
+}
+
+static void
+scsi_log_print_sense_hdr(const struct scsi_device *sdev, const char *name,
+			 int tag, const struct scsi_sense_hdr *sshdr)
+{
+	char *logbuf;
+	size_t off, logbuf_len;
+
+	logbuf = scsi_log_reserve_buffer(&logbuf_len);
+	if (!logbuf)
+		return;
+	off = sdev_format_header(logbuf, logbuf_len, name, tag);
+	off += scsi_format_sense_hdr(logbuf + off, logbuf_len - off, sshdr);
+	dev_printk(KERN_INFO, &sdev->sdev_gendev, "%s", logbuf);
+	scsi_log_release_buffer(logbuf);
+
+	logbuf = scsi_log_reserve_buffer(&logbuf_len);
+	if (!logbuf)
+		return;
+	off = sdev_format_header(logbuf, logbuf_len, name, tag);
+	off += scsi_format_extd_sense(logbuf + off, logbuf_len - off,
+				      sshdr->asc, sshdr->ascq);
+	dev_printk(KERN_INFO, &sdev->sdev_gendev, "%s", logbuf);
+	scsi_log_release_buffer(logbuf);
+}
+
+static void
+scsi_log_print_sense(const struct scsi_device *sdev, const char *name, int tag,
+		     const unsigned char *sense_buffer, int sense_len)
+{
+	struct scsi_sense_hdr sshdr;
+
+	if (scsi_normalize_sense(sense_buffer, sense_len, &sshdr))
+		scsi_log_print_sense_hdr(sdev, name, tag, &sshdr);
+	else
+		scsi_log_dump_sense(sdev, name, tag, sense_buffer, sense_len);
+}
+
+/*
+ * Print normalized SCSI sense header with a prefix.
+ */
+void
+scsi_print_sense_hdr(const struct scsi_device *sdev, const char *name,
+		     const struct scsi_sense_hdr *sshdr)
+{
+	scsi_log_print_sense_hdr(sdev, name, -1, sshdr);
+}
+EXPORT_SYMBOL(scsi_print_sense_hdr);
+
+/* Normalize and print sense buffer with name prefix */
+void __scsi_print_sense(const struct scsi_device *sdev, const char *name,
+			const unsigned char *sense_buffer, int sense_len)
+{
+	scsi_log_print_sense(sdev, name, -1, sense_buffer, sense_len);
+}
+EXPORT_SYMBOL(__scsi_print_sense);
+
+/* Normalize and print sense buffer in SCSI command */
+void scsi_print_sense(struct scsi_cmnd *cmd)
+{
+	scsi_log_print_sense(cmd->device, scmd_name(cmd),
+			     scsi_cmd_to_rq(cmd)->tag, cmd->sense_buffer,
+			     SCSI_SENSE_BUFFERSIZE);
+}
+EXPORT_SYMBOL(scsi_print_sense);
+
+void scsi_print_result(struct scsi_cmnd *cmd, const char *msg, int disposition)
+{
+	char *logbuf;
+	size_t off, logbuf_len;
+	const char *mlret_string = scsi_mlreturn_string(disposition);
+	const char *hb_string = scsi_hostbyte_string(cmd->result);
+	unsigned long cmd_age = (jiffies - cmd->jiffies_at_alloc) / HZ;
+
+	logbuf = scsi_log_reserve_buffer(&logbuf_len);
+	if (!logbuf)
+		return;
+
+	off = sdev_format_header(logbuf, logbuf_len, scmd_name(cmd),
+				 scsi_cmd_to_rq(cmd)->tag);
+
+	if (off >= logbuf_len)
+		goto out_printk;
+
+	if (msg) {
+		off += scnprintf(logbuf + off, logbuf_len - off,
+				 "%s: ", msg);
+		if (WARN_ON(off >= logbuf_len))
+			goto out_printk;
+	}
+	if (mlret_string)
+		off += scnprintf(logbuf + off, logbuf_len - off,
+				 "%s ", mlret_string);
+	else
+		off += scnprintf(logbuf + off, logbuf_len - off,
+				 "UNKNOWN(0x%02x) ", disposition);
+	if (WARN_ON(off >= logbuf_len))
+		goto out_printk;
+
+	off += scnprintf(logbuf + off, logbuf_len - off, "Result: ");
+	if (WARN_ON(off >= logbuf_len))
+		goto out_printk;
+
+	if (hb_string)
+		off += scnprintf(logbuf + off, logbuf_len - off,
+				 "hostbyte=%s ", hb_string);
+	else
+		off += scnprintf(logbuf + off, logbuf_len - off,
+				 "hostbyte=0x%02x ", host_byte(cmd->result));
+	if (WARN_ON(off >= logbuf_len))
+		goto out_printk;
+
+	off += scnprintf(logbuf + off, logbuf_len - off,
+			 "driverbyte=DRIVER_OK ");
+
+	off += scnprintf(logbuf + off, logbuf_len - off,
+			 "cmd_age=%lus", cmd_age);
+
+out_printk:
+	dev_printk(KERN_INFO, &cmd->device->sdev_gendev, "%s", logbuf);
+	scsi_log_release_buffer(logbuf);
+}
+EXPORT_SYMBOL(scsi_print_result);