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, 401 insertions, 0 deletions

diff --git a/drivers/scsi/scsi_common.c b/drivers/scsi/scsi_common.c
new file mode 100644
index 000000000..e1a2a62b6
--- /dev/null
+++ b/drivers/scsi/scsi_common.c
@@ -0,0 +1,401 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * SCSI functions used by both the initiator and the target code.
+ */
+
+#include <linux/bug.h>
+#include <linux/kernel.h>
+#include <linux/string.h>
+#include <linux/errno.h>
+#include <linux/module.h>
+#include <uapi/linux/pr.h>
+#include <linux/unaligned.h>
+#include <scsi/scsi_common.h>
+
+MODULE_DESCRIPTION("SCSI functions used by both the initiator and the target code");
+MODULE_LICENSE("GPL v2");
+
+/* Command group 3 is reserved and should never be used.  */
+const unsigned char scsi_command_size_tbl[8] = {
+	6, 10, 10, 12, 16, 12, 10, 10
+};
+EXPORT_SYMBOL(scsi_command_size_tbl);
+
+/* NB: These are exposed through /proc/scsi/scsi and form part of the ABI.
+ * You may not alter any existing entry (although adding new ones is
+ * encouraged once assigned by ANSI/INCITS T10).
+ */
+static const char *const scsi_device_types[] = {
+	"Direct-Access    ",
+	"Sequential-Access",
+	"Printer          ",
+	"Processor        ",
+	"WORM             ",
+	"CD-ROM           ",
+	"Scanner          ",
+	"Optical Device   ",
+	"Medium Changer   ",
+	"Communications   ",
+	"ASC IT8          ",
+	"ASC IT8          ",
+	"RAID             ",
+	"Enclosure        ",
+	"Direct-Access-RBC",
+	"Optical card     ",
+	"Bridge controller",
+	"Object storage   ",
+	"Automation/Drive ",
+	"Security Manager ",
+	"Direct-Access-ZBC",
+};
+
+/**
+ * scsi_device_type - Return 17-char string indicating device type.
+ * @type: type number to look up
+ */
+const char *scsi_device_type(unsigned type)
+{
+	if (type == 0x1e)
+		return "Well-known LUN   ";
+	if (type == 0x1f)
+		return "No Device        ";
+	if (type >= ARRAY_SIZE(scsi_device_types))
+		return "Unknown          ";
+	return scsi_device_types[type];
+}
+EXPORT_SYMBOL(scsi_device_type);
+
+enum pr_type scsi_pr_type_to_block(enum scsi_pr_type type)
+{
+	switch (type) {
+	case SCSI_PR_WRITE_EXCLUSIVE:
+		return PR_WRITE_EXCLUSIVE;
+	case SCSI_PR_EXCLUSIVE_ACCESS:
+		return PR_EXCLUSIVE_ACCESS;
+	case SCSI_PR_WRITE_EXCLUSIVE_REG_ONLY:
+		return PR_WRITE_EXCLUSIVE_REG_ONLY;
+	case SCSI_PR_EXCLUSIVE_ACCESS_REG_ONLY:
+		return PR_EXCLUSIVE_ACCESS_REG_ONLY;
+	case SCSI_PR_WRITE_EXCLUSIVE_ALL_REGS:
+		return PR_WRITE_EXCLUSIVE_ALL_REGS;
+	case SCSI_PR_EXCLUSIVE_ACCESS_ALL_REGS:
+		return PR_EXCLUSIVE_ACCESS_ALL_REGS;
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(scsi_pr_type_to_block);
+
+enum scsi_pr_type block_pr_type_to_scsi(enum pr_type type)
+{
+	switch (type) {
+	case PR_WRITE_EXCLUSIVE:
+		return SCSI_PR_WRITE_EXCLUSIVE;
+	case PR_EXCLUSIVE_ACCESS:
+		return SCSI_PR_EXCLUSIVE_ACCESS;
+	case PR_WRITE_EXCLUSIVE_REG_ONLY:
+		return SCSI_PR_WRITE_EXCLUSIVE_REG_ONLY;
+	case PR_EXCLUSIVE_ACCESS_REG_ONLY:
+		return SCSI_PR_EXCLUSIVE_ACCESS_REG_ONLY;
+	case PR_WRITE_EXCLUSIVE_ALL_REGS:
+		return SCSI_PR_WRITE_EXCLUSIVE_ALL_REGS;
+	case PR_EXCLUSIVE_ACCESS_ALL_REGS:
+		return SCSI_PR_EXCLUSIVE_ACCESS_ALL_REGS;
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(block_pr_type_to_scsi);
+
+/**
+ * scsilun_to_int - convert a scsi_lun to an int
+ * @scsilun:	struct scsi_lun to be converted.
+ *
+ * Description:
+ *     Convert @scsilun from a struct scsi_lun to a four-byte host byte-ordered
+ *     integer, and return the result. The caller must check for
+ *     truncation before using this function.
+ *
+ * Notes:
+ *     For a description of the LUN format, post SCSI-3 see the SCSI
+ *     Architecture Model, for SCSI-3 see the SCSI Controller Commands.
+ *
+ *     Given a struct scsi_lun of: d2 04 0b 03 00 00 00 00, this function
+ *     returns the integer: 0x0b03d204
+ *
+ *     This encoding will return a standard integer LUN for LUNs smaller
+ *     than 256, which typically use a single level LUN structure with
+ *     addressing method 0.
+ */
+u64 scsilun_to_int(struct scsi_lun *scsilun)
+{
+	int i;
+	u64 lun;
+
+	lun = 0;
+	for (i = 0; i < sizeof(lun); i += 2)
+		lun = lun | (((u64)scsilun->scsi_lun[i] << ((i + 1) * 8)) |
+			     ((u64)scsilun->scsi_lun[i + 1] << (i * 8)));
+	return lun;
+}
+EXPORT_SYMBOL(scsilun_to_int);
+
+/**
+ * int_to_scsilun - reverts an int into a scsi_lun
+ * @lun:        integer to be reverted
+ * @scsilun:	struct scsi_lun to be set.
+ *
+ * Description:
+ *     Reverts the functionality of the scsilun_to_int, which packed
+ *     an 8-byte lun value into an int. This routine unpacks the int
+ *     back into the lun value.
+ *
+ * Notes:
+ *     Given an integer : 0x0b03d204, this function returns a
+ *     struct scsi_lun of: d2 04 0b 03 00 00 00 00
+ *
+ */
+void int_to_scsilun(u64 lun, struct scsi_lun *scsilun)
+{
+	int i;
+
+	memset(scsilun->scsi_lun, 0, sizeof(scsilun->scsi_lun));
+
+	for (i = 0; i < sizeof(lun); i += 2) {
+		scsilun->scsi_lun[i] = (lun >> 8) & 0xFF;
+		scsilun->scsi_lun[i+1] = lun & 0xFF;
+		lun = lun >> 16;
+	}
+}
+EXPORT_SYMBOL(int_to_scsilun);
+
+/**
+ * scsi_normalize_sense - normalize main elements from either fixed or
+ *			descriptor sense data format into a common format.
+ *
+ * @sense_buffer:	byte array containing sense data returned by device
+ * @sb_len:		number of valid bytes in sense_buffer
+ * @sshdr:		pointer to instance of structure that common
+ *			elements are written to.
+ *
+ * Notes:
+ *	The "main elements" from sense data are: response_code, sense_key,
+ *	asc, ascq and additional_length (only for descriptor format).
+ *
+ *	Typically this function can be called after a device has
+ *	responded to a SCSI command with the CHECK_CONDITION status.
+ *
+ * Return value:
+ *	true if valid sense data information found, else false;
+ */
+bool scsi_normalize_sense(const u8 *sense_buffer, int sb_len,
+			  struct scsi_sense_hdr *sshdr)
+{
+	memset(sshdr, 0, sizeof(struct scsi_sense_hdr));
+
+	if (!sense_buffer || !sb_len)
+		return false;
+
+	sshdr->response_code = (sense_buffer[0] & 0x7f);
+
+	if (!scsi_sense_valid(sshdr))
+		return false;
+
+	if (sshdr->response_code >= 0x72) {
+		/*
+		 * descriptor format
+		 */
+		if (sb_len > 1)
+			sshdr->sense_key = (sense_buffer[1] & 0xf);
+		if (sb_len > 2)
+			sshdr->asc = sense_buffer[2];
+		if (sb_len > 3)
+			sshdr->ascq = sense_buffer[3];
+		if (sb_len > 7)
+			sshdr->additional_length = sense_buffer[7];
+	} else {
+		/*
+		 * fixed format
+		 */
+		if (sb_len > 2)
+			sshdr->sense_key = (sense_buffer[2] & 0xf);
+		if (sb_len > 7) {
+			sb_len = min(sb_len, sense_buffer[7] + 8);
+			if (sb_len > 12)
+				sshdr->asc = sense_buffer[12];
+			if (sb_len > 13)
+				sshdr->ascq = sense_buffer[13];
+		}
+	}
+
+	return true;
+}
+EXPORT_SYMBOL(scsi_normalize_sense);
+
+/**
+ * scsi_sense_desc_find - search for a given descriptor type in	descriptor sense data format.
+ * @sense_buffer:	byte array of descriptor format sense data
+ * @sb_len:		number of valid bytes in sense_buffer
+ * @desc_type:		value of descriptor type to find
+ *			(e.g. 0 -> information)
+ *
+ * Notes:
+ *	only valid when sense data is in descriptor format
+ *
+ * Return value:
+ *	pointer to start of (first) descriptor if found else NULL
+ */
+const u8 * scsi_sense_desc_find(const u8 * sense_buffer, int sb_len,
+				int desc_type)
+{
+	int add_sen_len, add_len, desc_len, k;
+	const u8 * descp;
+
+	if ((sb_len < 8) || (0 == (add_sen_len = sense_buffer[7])))
+		return NULL;
+	if ((sense_buffer[0] < 0x72) || (sense_buffer[0] > 0x73))
+		return NULL;
+	add_sen_len = (add_sen_len < (sb_len - 8)) ?
+			add_sen_len : (sb_len - 8);
+	descp = &sense_buffer[8];
+	for (desc_len = 0, k = 0; k < add_sen_len; k += desc_len) {
+		descp += desc_len;
+		add_len = (k < (add_sen_len - 1)) ? descp[1]: -1;
+		desc_len = add_len + 2;
+		if (descp[0] == desc_type)
+			return descp;
+		if (add_len < 0) // short descriptor ??
+			break;
+	}
+	return NULL;
+}
+EXPORT_SYMBOL(scsi_sense_desc_find);
+
+/**
+ * scsi_build_sense_buffer - build sense data in a buffer
+ * @desc:	Sense format (non-zero == descriptor format,
+ *              0 == fixed format)
+ * @buf:	Where to build sense data
+ * @key:	Sense key
+ * @asc:	Additional sense code
+ * @ascq:	Additional sense code qualifier
+ *
+ **/
+void scsi_build_sense_buffer(int desc, u8 *buf, u8 key, u8 asc, u8 ascq)
+{
+	if (desc) {
+		buf[0] = 0x72;	/* descriptor, current */
+		buf[1] = key;
+		buf[2] = asc;
+		buf[3] = ascq;
+		buf[7] = 0;
+	} else {
+		buf[0] = 0x70;	/* fixed, current */
+		buf[2] = key;
+		buf[7] = 0xa;
+		buf[12] = asc;
+		buf[13] = ascq;
+	}
+}
+EXPORT_SYMBOL(scsi_build_sense_buffer);
+
+/**
+ * scsi_set_sense_information - set the information field in a
+ *		formatted sense data buffer
+ * @buf:	Where to build sense data
+ * @buf_len:    buffer length
+ * @info:	64-bit information value to be set
+ *
+ * Return value:
+ *	0 on success or -EINVAL for invalid sense buffer length
+ **/
+int scsi_set_sense_information(u8 *buf, int buf_len, u64 info)
+{
+	if ((buf[0] & 0x7f) == 0x72) {
+		u8 *ucp, len;
+
+		len = buf[7];
+		ucp = (char *)scsi_sense_desc_find(buf, len + 8, 0);
+		if (!ucp) {
+			buf[7] = len + 0xc;
+			ucp = buf + 8 + len;
+		}
+
+		if (buf_len < len + 0xc)
+			/* Not enough room for info */
+			return -EINVAL;
+
+		ucp[0] = 0;
+		ucp[1] = 0xa;
+		ucp[2] = 0x80; /* Valid bit */
+		ucp[3] = 0;
+		put_unaligned_be64(info, &ucp[4]);
+	} else if ((buf[0] & 0x7f) == 0x70) {
+		/*
+		 * Only set the 'VALID' bit if we can represent the value
+		 * correctly; otherwise just fill out the lower bytes and
+		 * clear the 'VALID' flag.
+		 */
+		if (info <= 0xffffffffUL)
+			buf[0] |= 0x80;
+		else
+			buf[0] &= 0x7f;
+		put_unaligned_be32((u32)info, &buf[3]);
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL(scsi_set_sense_information);
+
+/**
+ * scsi_set_sense_field_pointer - set the field pointer sense key
+ *		specific information in a formatted sense data buffer
+ * @buf:	Where to build sense data
+ * @buf_len:    buffer length
+ * @fp:		field pointer to be set
+ * @bp:		bit pointer to be set
+ * @cd:		command/data bit
+ *
+ * Return value:
+ *	0 on success or -EINVAL for invalid sense buffer length
+ */
+int scsi_set_sense_field_pointer(u8 *buf, int buf_len, u16 fp, u8 bp, bool cd)
+{
+	u8 *ucp, len;
+
+	if ((buf[0] & 0x7f) == 0x72) {
+		len = buf[7];
+		ucp = (char *)scsi_sense_desc_find(buf, len + 8, 2);
+		if (!ucp) {
+			buf[7] = len + 8;
+			ucp = buf + 8 + len;
+		}
+
+		if (buf_len < len + 8)
+			/* Not enough room for info */
+			return -EINVAL;
+
+		ucp[0] = 2;
+		ucp[1] = 6;
+		ucp[4] = 0x80; /* Valid bit */
+		if (cd)
+			ucp[4] |= 0x40;
+		if (bp < 0x8)
+			ucp[4] |= 0x8 | bp;
+		put_unaligned_be16(fp, &ucp[5]);
+	} else if ((buf[0] & 0x7f) == 0x70) {
+		len = buf[7];
+		if (len < 18)
+			buf[7] = 18;
+
+		buf[15] = 0x80;
+		if (cd)
+			buf[15] |= 0x40;
+		if (bp < 0x8)
+			buf[15] |= 0x8 | bp;
+		put_unaligned_be16(fp, &buf[16]);
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL(scsi_set_sense_field_pointer);