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, 79 insertions, 0 deletions

diff --git a/drivers/video/logo/Kconfig b/drivers/video/logo/Kconfig
new file mode 100644
index 000000000..cda15b958
--- /dev/null
+++ b/drivers/video/logo/Kconfig
@@ -0,0 +1,79 @@
+# SPDX-License-Identifier: GPL-2.0-only
+#
+# Logo configuration
+#
+
+menuconfig LOGO
+	bool "Bootup logo"
+	depends on FB_CORE || SGI_NEWPORT_CONSOLE
+	help
+	  Enable and select frame buffer bootup logos.
+	  Monochrome logos will also be used by the DRM panic handler, if
+	  enabled.
+
+if LOGO
+
+config FB_LOGO_EXTRA
+	bool
+	depends on FB=y
+	default y if SPU_BASE
+
+config LOGO_LINUX_MONO
+	bool "Standard black and white Linux logo"
+
+config LOGO_LINUX_MONO_FILE
+	string "Monochrome logo .pbm file"
+	depends on LOGO_LINUX_MONO
+	default "drivers/video/logo/logo_superh_mono.pbm" if SUPERH
+	default "drivers/video/logo/logo_linux_mono.pbm"
+	help
+	  Takes a path to a monochromatic logo in the portable pixmap file
+	  format (.pbm). This defaults to the Tux penguin.
+
+	  For example, the below ImageMagick command can be used to reduce
+	  an image to black and white and convert it into a pbm file:
+
+	    magick source_image -compress none destination.pbm
+
+config LOGO_LINUX_VGA16
+	bool "Standard 16-color Linux logo"
+
+config LOGO_LINUX_VGA16_FILE
+	string "16-color logo .ppm file"
+	depends on LOGO_LINUX_VGA16
+	default "drivers/video/logo/logo_superh_vga16.ppm" if SUPERH
+	default "drivers/video/logo/logo_linux_vga16.ppm"
+	help
+	  Takes a path to a logo in the portable pixmap file format (.ppm),
+	  using the 16 colors from the drivers/video/logo/clut_vga16.ppm
+	  palette. This defaults to the Tux penguin.
+
+	  For example, the below ImageMagick command can be used to reduce an
+	  image to the VGA 16 colors palette and convert into a ppm file:
+
+	    magick source_image -compress none \
+	      -remap drivers/video/logo/clut_vga16.ppm destination.ppm
+
+config LOGO_LINUX_CLUT224
+	bool "Standard 224-color Linux logo"
+	default y
+
+config LOGO_LINUX_CLUT224_FILE
+	string "224-color logo .ppm file"
+	depends on LOGO_LINUX_CLUT224
+	default "drivers/video/logo/logo_dec_clut224.ppm" if MACH_DECSTATION || ALPHA
+	default "drivers/video/logo/logo_parisc_clut224.ppm" if PARISC
+	default "drivers/video/logo/logo_sgi_clut224.ppm" if SGI_IP22 || SGI_IP27 || SGI_IP32
+	default "drivers/video/logo/logo_sun_clut224.ppm" if SPARC
+	default "drivers/video/logo/logo_superh_clut224.ppm" if SUPERH
+	default "drivers/video/logo/logo_linux_clut224.ppm"
+	help
+	  Takes a path to a 224-color logo in the portable pixmap file
+	  format (.ppm). This defaults to the Tux penguin.
+
+	  For example, the below ImageMagick command can be used to reduce
+	  an image palette to 224 colors and convert it into a ppm file:
+
+	    magick source_image -compress none -colors 224 destination.ppm
+
+endif # LOGO