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, 119 insertions, 0 deletions

diff --git a/include/drm/drm_prime.h b/include/drm/drm_prime.h
new file mode 100644
index 000000000..f50f862f0
--- /dev/null
+++ b/include/drm/drm_prime.h
@@ -0,0 +1,119 @@
+/*
+ * Copyright © 2012 Red Hat
+ * Copyright 1999 Precision Insight, Inc., Cedar Park, Texas.
+ * Copyright 2000 VA Linux Systems, Inc., Sunnyvale, California.
+ * Copyright (c) 2009-2010, Code Aurora Forum.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ *
+ * Authors:
+ *      Dave Airlie <airlied@redhat.com>
+ *      Rob Clark <rob.clark@linaro.org>
+ *
+ */
+
+#ifndef __DRM_PRIME_H__
+#define __DRM_PRIME_H__
+
+#include <linux/mutex.h>
+#include <linux/rbtree.h>
+#include <linux/scatterlist.h>
+
+/**
+ * struct drm_prime_file_private - per-file tracking for PRIME
+ *
+ * This just contains the internal &struct dma_buf and handle caches for each
+ * &struct drm_file used by the PRIME core code.
+ */
+struct drm_prime_file_private {
+/* private: */
+	struct mutex lock;
+	struct rb_root dmabufs;
+	struct rb_root handles;
+};
+
+struct device;
+
+struct dma_buf_export_info;
+struct dma_buf;
+struct dma_buf_attachment;
+struct iosys_map;
+
+enum dma_data_direction;
+
+struct drm_device;
+struct drm_gem_object;
+struct drm_file;
+
+/* core prime functions */
+struct dma_buf *drm_gem_dmabuf_export(struct drm_device *dev,
+				      struct dma_buf_export_info *exp_info);
+void drm_gem_dmabuf_release(struct dma_buf *dma_buf);
+
+int drm_gem_prime_fd_to_handle(struct drm_device *dev,
+			       struct drm_file *file_priv, int prime_fd, uint32_t *handle);
+struct dma_buf *drm_gem_prime_handle_to_dmabuf(struct drm_device *dev,
+			       struct drm_file *file_priv, uint32_t handle,
+			       uint32_t flags);
+int drm_gem_prime_handle_to_fd(struct drm_device *dev,
+			       struct drm_file *file_priv, uint32_t handle, uint32_t flags,
+			       int *prime_fd);
+
+/* helper functions for exporting */
+int drm_gem_map_attach(struct dma_buf *dma_buf,
+		       struct dma_buf_attachment *attach);
+void drm_gem_map_detach(struct dma_buf *dma_buf,
+			struct dma_buf_attachment *attach);
+struct sg_table *drm_gem_map_dma_buf(struct dma_buf_attachment *attach,
+				     enum dma_data_direction dir);
+void drm_gem_unmap_dma_buf(struct dma_buf_attachment *attach,
+			   struct sg_table *sgt,
+			   enum dma_data_direction dir);
+int drm_gem_dmabuf_vmap(struct dma_buf *dma_buf, struct iosys_map *map);
+void drm_gem_dmabuf_vunmap(struct dma_buf *dma_buf, struct iosys_map *map);
+
+int drm_gem_prime_mmap(struct drm_gem_object *obj, struct vm_area_struct *vma);
+int drm_gem_dmabuf_mmap(struct dma_buf *dma_buf, struct vm_area_struct *vma);
+
+struct sg_table *drm_prime_pages_to_sg(struct drm_device *dev,
+				       struct page **pages, unsigned int nr_pages);
+struct dma_buf *drm_gem_prime_export(struct drm_gem_object *obj,
+				     int flags);
+
+unsigned long drm_prime_get_contiguous_size(struct sg_table *sgt);
+
+/* helper functions for importing */
+bool drm_gem_is_prime_exported_dma_buf(struct drm_device *dev,
+				       struct dma_buf *dma_buf);
+
+struct drm_gem_object *drm_gem_prime_import_dev(struct drm_device *dev,
+						struct dma_buf *dma_buf,
+						struct device *attach_dev);
+struct drm_gem_object *drm_gem_prime_import(struct drm_device *dev,
+					    struct dma_buf *dma_buf);
+
+void drm_prime_gem_destroy(struct drm_gem_object *obj, struct sg_table *sg);
+
+int drm_prime_sg_to_page_array(struct sg_table *sgt, struct page **pages,
+			       int max_pages);
+int drm_prime_sg_to_dma_addr_array(struct sg_table *sgt, dma_addr_t *addrs,
+				   int max_pages);
+
+#endif /* __DRM_PRIME_H__ */