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, 265 insertions, 0 deletions

diff --git a/arch/mips/sni/setup.c b/arch/mips/sni/setup.c
new file mode 100644
index 000000000..fc7da1228
--- /dev/null
+++ b/arch/mips/sni/setup.c
@@ -0,0 +1,265 @@
+/*
+ * Setup pointers to hardware-dependent routines.
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file "COPYING" in the main directory of this archive
+ * for more details.
+ *
+ * Copyright (C) 1996, 97, 98, 2000, 03, 04, 06 Ralf Baechle (ralf@linux-mips.org)
+ * Copyright (C) 2006,2007 Thomas Bogendoerfer (tsbogend@alpha.franken.de)
+ */
+#include <linux/eisa.h>
+#include <linux/init.h>
+#include <linux/export.h>
+#include <linux/console.h>
+#include <linux/screen_info.h>
+#include <linux/string.h>
+
+#ifdef CONFIG_FW_ARC
+#include <asm/fw/arc/types.h>
+#include <asm/sgialib.h>
+#endif
+
+#ifdef CONFIG_FW_SNIPROM
+#include <asm/mipsprom.h>
+#endif
+
+#include <asm/bootinfo.h>
+#include <asm/cpu.h>
+#include <asm/io.h>
+#include <asm/reboot.h>
+#include <asm/sni.h>
+
+unsigned int sni_brd_type;
+EXPORT_SYMBOL(sni_brd_type);
+
+extern void sni_machine_restart(char *command);
+extern void sni_machine_power_off(void);
+
+static void __init sni_display_setup(void)
+{
+#if defined(CONFIG_VGA_CONSOLE) && defined(CONFIG_FW_ARC)
+	static struct screen_info si;
+	DISPLAY_STATUS *di;
+
+	di = ArcGetDisplayStatus(1);
+
+	if (di) {
+		si.orig_x		= di->CursorXPosition;
+		si.orig_y		= di->CursorYPosition;
+		si.orig_video_cols	= di->CursorMaxXPosition;
+		si.orig_video_lines	= di->CursorMaxYPosition;
+		si.orig_video_isVGA	= VIDEO_TYPE_VGAC;
+		si.orig_video_points	= 16;
+
+		vgacon_register_screen(&si);
+	}
+#endif
+}
+
+static void __init sni_console_setup(void)
+{
+#ifndef CONFIG_FW_ARC
+	char *ctype;
+	char *cdev;
+	char *baud;
+	int port;
+	static char options[8] __initdata;
+
+	cdev = prom_getenv("console_dev");
+	if (strncmp(cdev, "tty", 3) == 0) {
+		ctype = prom_getenv("console");
+		switch (*ctype) {
+		default:
+		case 'l':
+			port = 0;
+			baud = prom_getenv("lbaud");
+			break;
+		case 'r':
+			port = 1;
+			baud = prom_getenv("rbaud");
+			break;
+		}
+		if (baud)
+			strscpy(options, baud);
+		if (strncmp(cdev, "tty552", 6) == 0)
+			add_preferred_console("ttyS", port,
+					      baud ? options : NULL);
+		else
+			add_preferred_console("ttySC", port,
+					      baud ? options : NULL);
+	}
+#endif
+}
+
+#ifdef DEBUG
+static void __init sni_idprom_dump(void)
+{
+	int	i;
+
+	pr_debug("SNI IDProm dump:\n");
+	for (i = 0; i < 256; i++) {
+		if (i%16 == 0)
+			pr_debug("%04x ", i);
+
+		printk("%02x ", *(unsigned char *) (SNI_IDPROM_BASE + i));
+
+		if (i % 16 == 15)
+			printk("\n");
+	}
+}
+#endif
+
+void __init plat_mem_setup(void)
+{
+	int cputype;
+
+	set_io_port_base(SNI_PORT_BASE);
+//	ioport_resource.end = sni_io_resource.end;
+
+	/*
+	 * Setup (E)ISA I/O memory access stuff
+	 */
+#ifdef CONFIG_EISA
+	EISA_bus = 1;
+#endif
+
+	sni_brd_type = *(unsigned char *)SNI_IDPROM_BRDTYPE;
+	cputype = *(unsigned char *)SNI_IDPROM_CPUTYPE;
+	switch (sni_brd_type) {
+	case SNI_BRD_TOWER_OASIC:
+		switch (cputype) {
+		case SNI_CPU_M8030:
+			system_type = "RM400-330";
+			break;
+		case SNI_CPU_M8031:
+			system_type = "RM400-430";
+			break;
+		case SNI_CPU_M8037:
+			system_type = "RM400-530";
+			break;
+		case SNI_CPU_M8034:
+			system_type = "RM400-730";
+			break;
+		default:
+			system_type = "RM400-xxx";
+			break;
+		}
+		break;
+	case SNI_BRD_MINITOWER:
+		switch (cputype) {
+		case SNI_CPU_M8021:
+		case SNI_CPU_M8043:
+			system_type = "RM400-120";
+			break;
+		case SNI_CPU_M8040:
+			system_type = "RM400-220";
+			break;
+		case SNI_CPU_M8053:
+			system_type = "RM400-225";
+			break;
+		case SNI_CPU_M8050:
+			system_type = "RM400-420";
+			break;
+		default:
+			system_type = "RM400-xxx";
+			break;
+		}
+		break;
+	case SNI_BRD_PCI_TOWER:
+		system_type = "RM400-Cxx";
+		break;
+	case SNI_BRD_RM200:
+		system_type = "RM200-xxx";
+		break;
+	case SNI_BRD_PCI_MTOWER:
+		system_type = "RM300-Cxx";
+		break;
+	case SNI_BRD_PCI_DESKTOP:
+		switch (read_c0_prid() & PRID_IMP_MASK) {
+		case PRID_IMP_R4600:
+		case PRID_IMP_R4700:
+			system_type = "RM200-C20";
+			break;
+		case PRID_IMP_R5000:
+			system_type = "RM200-C40";
+			break;
+		default:
+			system_type = "RM200-Cxx";
+			break;
+		}
+		break;
+	case SNI_BRD_PCI_TOWER_CPLUS:
+		system_type = "RM400-Exx";
+		break;
+	case SNI_BRD_PCI_MTOWER_CPLUS:
+		system_type = "RM300-Exx";
+		break;
+	}
+	pr_debug("Found SNI brdtype %02x name %s\n", sni_brd_type, system_type);
+
+#ifdef DEBUG
+	sni_idprom_dump();
+#endif
+
+	switch (sni_brd_type) {
+	case SNI_BRD_10:
+	case SNI_BRD_10NEW:
+	case SNI_BRD_TOWER_OASIC:
+	case SNI_BRD_MINITOWER:
+		sni_a20r_init();
+		break;
+
+	case SNI_BRD_PCI_TOWER:
+	case SNI_BRD_PCI_TOWER_CPLUS:
+		sni_pcit_init();
+		break;
+
+	case SNI_BRD_RM200:
+		sni_rm200_init();
+		break;
+
+	case SNI_BRD_PCI_MTOWER:
+	case SNI_BRD_PCI_DESKTOP:
+	case SNI_BRD_PCI_MTOWER_CPLUS:
+		sni_pcimt_init();
+		break;
+	}
+
+	_machine_restart = sni_machine_restart;
+	pm_power_off = sni_machine_power_off;
+
+	sni_display_setup();
+	sni_console_setup();
+}
+
+#ifdef CONFIG_PCI
+
+#include <linux/pci.h>
+#include <video/vga.h>
+#include <video/cirrus.h>
+
+static void quirk_cirrus_ram_size(struct pci_dev *dev)
+{
+	u16 cmd;
+
+	/*
+	 * firmware doesn't set the ram size correct, so we
+	 * need to do it here, otherwise we get screen corruption
+	 * on older Cirrus chips
+	 */
+	pci_read_config_word(dev, PCI_COMMAND, &cmd);
+	if ((cmd & (PCI_COMMAND_IO|PCI_COMMAND_MEMORY))
+		== (PCI_COMMAND_IO|PCI_COMMAND_MEMORY)) {
+		vga_wseq(NULL, CL_SEQR6, 0x12); /* unlock all extension registers */
+		vga_wseq(NULL, CL_SEQRF, 0x18);
+	}
+}
+
+DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_CIRRUS, PCI_DEVICE_ID_CIRRUS_5434_8,
+			quirk_cirrus_ram_size);
+DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_CIRRUS, PCI_DEVICE_ID_CIRRUS_5436,
+			quirk_cirrus_ram_size);
+DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_CIRRUS, PCI_DEVICE_ID_CIRRUS_5446,
+			quirk_cirrus_ram_size);
+#endif