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, 147 insertions, 0 deletions

diff --git a/drivers/scsi/ppa.h b/drivers/scsi/ppa.h
new file mode 100644
index 000000000..098bcf7b9
--- /dev/null
+++ b/drivers/scsi/ppa.h
@@ -0,0 +1,147 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*  Driver for the PPA3 parallel port SCSI HBA embedded in 
+ * the Iomega ZIP drive
+ * 
+ * (c) 1996     Grant R. Guenther  grant@torque.net
+ *              David Campbell
+ *
+ *      All comments to David.
+ */
+
+#ifndef _PPA_H
+#define _PPA_H
+
+#define   PPA_VERSION   "2.07 (for Linux 2.4.x)"
+
+/* 
+ * this driver has been hacked by Matteo Frigo (athena@theory.lcs.mit.edu)
+ * to support EPP and scatter-gather.                        [0.26-athena]
+ *
+ * additional hacks by David Campbell
+ * in response to this driver "mis-behaving" on his machine.
+ *      Fixed EPP to handle "software" changing of EPP port data direction.
+ *      Chased down EPP timeouts
+ *      Made this driver "kernel version friendly"           [0.28-athena]
+ *
+ * [ Stuff removed ]
+ *
+ * Corrected ppa.h for 2.1.x kernels (>=2.1.85)
+ * Modified "Nat Semi Kludge" for extended chipsets
+ *                                                      [1.41]
+ *
+ * Fixed id_probe for EPP 1.9 chipsets (misdetected as EPP 1.7)
+ *                                                      [1.42]
+ *
+ * Development solely for 2.1.x kernels from now on!
+ *                                                      [2.00]
+ *
+ * Hack and slash at the init code (EPP device check routine)
+ * Added INSANE option.
+ *                                                      [2.01]
+ *
+ * Patch applied to sync against the 2.1.x kernel code
+ * Included qboot_zip.sh
+ *                                                      [2.02]
+ *
+ * Cleaned up the mess left by someone else trying to fix the
+ * asm section to keep egcc happy. The asm section no longer
+ * exists, the nibble code is *almost* as fast as the asm code
+ * providing it is compiled with egcc.
+ *
+ * Other clean ups include the follow changes:
+ *    CONFIG_SCSI_PPA_HAVE_PEDANTIC => CONFIG_SCSI_IZIP_EPP16
+ *    added CONFIG_SCSI_IZIP_SLOW_CTR option
+ *                                                      [2.03]
+ *
+ * Use ppa_wait() to check for ready AND connected status bits
+ * Add ppa_wait() calls to ppa_completion()
+ *  by Peter Cherriman <pjc@ecs.soton.ac.uk> and
+ *     Tim Waugh <twaugh@redhat.com>
+ *							[2.04]
+ *
+ * Fix kernel panic on scsi timeout, 2000-08-18		[2.05]
+ *
+ * Avoid io_request_lock problems.
+ * John Cavan <johncavan@home.com>			[2.06]
+ *
+ * Busy wait for connected status bit in ppa_completion()
+ *  in order to cope with some hardware that has this bit low
+ *  for short periods of time.
+ * Add udelay() to ppa_select()
+ *  by Peter Cherriman <pjc@ecs.soton.ac.uk> and
+ *     Oleg Makarenko <omakarenko@cyberplat.ru>         
+ *                                                      [2.07]
+ */
+/* ------ END OF USER CONFIGURABLE PARAMETERS ----- */
+
+#include  <linux/stddef.h>
+#include  <linux/module.h>
+#include  <linux/kernel.h>
+#include  <linux/ioport.h>
+#include  <linux/delay.h>
+#include  <linux/proc_fs.h>
+#include  <linux/stat.h>
+#include  <linux/blkdev.h>
+#include  <linux/sched.h>
+#include  <linux/interrupt.h>
+
+#include  <asm/io.h>
+#include  <scsi/scsi_host.h>
+/* batteries not included :-) */
+
+/*
+ * modes in which the driver can operate 
+ */
+#define   PPA_AUTODETECT        0	/* Autodetect mode                */
+#define   PPA_NIBBLE            1	/* work in standard 4 bit mode    */
+#define   PPA_PS2               2	/* PS/2 byte mode         */
+#define   PPA_EPP_8             3	/* EPP mode, 8 bit                */
+#define   PPA_EPP_16            4	/* EPP mode, 16 bit               */
+#define   PPA_EPP_32            5	/* EPP mode, 32 bit               */
+#define   PPA_UNKNOWN           6	/* Just in case...                */
+
+static char *PPA_MODE_STRING[] =
+{
+    "Autodetect",
+    "SPP",
+    "PS/2",
+    "EPP 8 bit",
+    "EPP 16 bit",
+    "EPP 32 bit",
+    "Unknown"};
+
+/* other options */
+#define PPA_BURST_SIZE	512	/* data burst size */
+#define PPA_SELECT_TMO  5000	/* how long to wait for target ? */
+#define PPA_SPIN_TMO    50000	/* ppa_wait loop limiter */
+#define PPA_RECON_TMO   500	/* scsi reconnection loop limiter */
+#define PPA_DEBUG	0	/* debugging option */
+#define IN_EPP_MODE(x) (x == PPA_EPP_8 || x == PPA_EPP_16 || x == PPA_EPP_32)
+
+/* args to ppa_connect */
+#define CONNECT_EPP_MAYBE 1
+#define CONNECT_NORMAL  0
+
+#define r_dtr(x)        (unsigned char)inb((x))
+#define r_str(x)        (unsigned char)inb((x)+1)
+#define r_ctr(x)        (unsigned char)inb((x)+2)
+#define r_epp(x)        (unsigned char)inb((x)+4)
+#define r_fifo(x)       (unsigned char)inb((x)) /* x must be base_hi */
+					/* On PCI is base+0x400 != base_hi */
+#define r_ecr(x)        (unsigned char)inb((x)+0x2) /* x must be base_hi */
+
+#define w_dtr(x,y)      outb(y, (x))
+#define w_str(x,y)      outb(y, (x)+1)
+#define w_epp(x,y)      outb(y, (x)+4)
+#define w_fifo(x,y)     outb(y, (x))	/* x must be base_hi */
+#define w_ecr(x,y)      outb(y, (x)+0x2)/* x must be base_hi */
+
+#ifdef CONFIG_SCSI_IZIP_SLOW_CTR
+#define w_ctr(x,y)      outb_p(y, (x)+2)
+#else
+#define w_ctr(x,y)      outb(y, (x)+2)
+#endif
+
+static int ppa_engine(ppa_struct *, struct scsi_cmnd *);
+
+#endif				/* _PPA_H */