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, 587 insertions, 0 deletions

diff --git a/fs/orangefs/file.c b/fs/orangefs/file.c
new file mode 100644
index 000000000..42591252e
--- /dev/null
+++ b/fs/orangefs/file.c
@@ -0,0 +1,587 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * (C) 2001 Clemson University and The University of Chicago
+ * Copyright 2018 Omnibond Systems, L.L.C.
+ *
+ * See COPYING in top-level directory.
+ */
+
+/*
+ *  Linux VFS file operations.
+ */
+
+#include "protocol.h"
+#include "orangefs-kernel.h"
+#include "orangefs-bufmap.h"
+#include <linux/fs.h>
+#include <linux/filelock.h>
+#include <linux/pagemap.h>
+
+static int flush_racache(struct inode *inode)
+{
+	struct orangefs_inode_s *orangefs_inode = ORANGEFS_I(inode);
+	struct orangefs_kernel_op_s *new_op;
+	int ret;
+
+	gossip_debug(GOSSIP_UTILS_DEBUG,
+	    "%s: %pU: Handle is %pU | fs_id %d\n", __func__,
+	    get_khandle_from_ino(inode), &orangefs_inode->refn.khandle,
+	    orangefs_inode->refn.fs_id);
+
+	new_op = op_alloc(ORANGEFS_VFS_OP_RA_FLUSH);
+	if (!new_op)
+		return -ENOMEM;
+	new_op->upcall.req.ra_cache_flush.refn = orangefs_inode->refn;
+
+	ret = service_operation(new_op, "orangefs_flush_racache",
+	    get_interruptible_flag(inode));
+
+	gossip_debug(GOSSIP_UTILS_DEBUG, "%s: got return value of %d\n",
+	    __func__, ret);
+
+	op_release(new_op);
+	return ret;
+}
+
+/*
+ * Post and wait for the I/O upcall to finish
+ */
+ssize_t wait_for_direct_io(enum ORANGEFS_io_type type, struct inode *inode,
+	loff_t *offset, struct iov_iter *iter, size_t total_size,
+	loff_t readahead_size, struct orangefs_write_range *wr,
+	int *index_return, struct file *file)
+{
+	struct orangefs_inode_s *orangefs_inode = ORANGEFS_I(inode);
+	struct orangefs_khandle *handle = &orangefs_inode->refn.khandle;
+	struct orangefs_kernel_op_s *new_op = NULL;
+	int buffer_index;
+	ssize_t ret;
+	size_t copy_amount;
+	bool open_for_read;
+	bool open_for_write;
+
+	new_op = op_alloc(ORANGEFS_VFS_OP_FILE_IO);
+	if (!new_op)
+		return -ENOMEM;
+
+	/* synchronous I/O */
+	new_op->upcall.req.io.readahead_size = readahead_size;
+	new_op->upcall.req.io.io_type = type;
+	new_op->upcall.req.io.refn = orangefs_inode->refn;
+
+populate_shared_memory:
+	/* get a shared buffer index */
+	buffer_index = orangefs_bufmap_get();
+	if (buffer_index < 0) {
+		ret = buffer_index;
+		gossip_debug(GOSSIP_FILE_DEBUG,
+			     "%s: orangefs_bufmap_get failure (%zd)\n",
+			     __func__, ret);
+		goto out;
+	}
+	gossip_debug(GOSSIP_FILE_DEBUG,
+		     "%s(%pU): GET op %p -> buffer_index %d\n",
+		     __func__,
+		     handle,
+		     new_op,
+		     buffer_index);
+
+	new_op->uses_shared_memory = 1;
+	new_op->upcall.req.io.buf_index = buffer_index;
+	new_op->upcall.req.io.count = total_size;
+	new_op->upcall.req.io.offset = *offset;
+	if (type == ORANGEFS_IO_WRITE && wr) {
+		new_op->upcall.uid = from_kuid(&init_user_ns, wr->uid);
+		new_op->upcall.gid = from_kgid(&init_user_ns, wr->gid);
+	}
+	/*
+	 * Orangefs has no open, and orangefs checks file permissions
+	 * on each file access. Posix requires that file permissions
+	 * be checked on open and nowhere else. Orangefs-through-the-kernel
+	 * needs to seem posix compliant.
+	 *
+	 * The VFS opens files, even if the filesystem provides no
+	 * method. We can see if a file was successfully opened for
+	 * read and or for write by looking at file->f_mode.
+	 *
+	 * When writes are flowing from the page cache, file is no
+	 * longer available. We can trust the VFS to have checked
+	 * file->f_mode before writing to the page cache.
+	 *
+	 * The mode of a file might change between when it is opened
+	 * and IO commences, or it might be created with an arbitrary mode.
+	 *
+	 * We'll make sure we don't hit EACCES during the IO stage by
+	 * using UID 0. Some of the time we have access without changing
+	 * to UID 0 - how to check?
+	 */
+	if (file) {
+		open_for_write = file->f_mode & FMODE_WRITE;
+		open_for_read = file->f_mode & FMODE_READ;
+	} else {
+		open_for_write = 1;
+		open_for_read = 0; /* not relevant? */
+	}
+	if ((type == ORANGEFS_IO_WRITE) && open_for_write)
+		new_op->upcall.uid = 0;
+	if ((type == ORANGEFS_IO_READ) && open_for_read)
+		new_op->upcall.uid = 0;
+
+	gossip_debug(GOSSIP_FILE_DEBUG,
+		     "%s(%pU): offset: %llu total_size: %zd\n",
+		     __func__,
+		     handle,
+		     llu(*offset),
+		     total_size);
+	/*
+	 * Stage 1: copy the buffers into client-core's address space
+	 */
+	if (type == ORANGEFS_IO_WRITE && total_size) {
+		ret = orangefs_bufmap_copy_from_iovec(iter, buffer_index,
+		    total_size);
+		if (ret < 0) {
+			gossip_err("%s: Failed to copy-in buffers. Please make sure that the pvfs2-client is running. %ld\n",
+			    __func__, (long)ret);
+			goto out;
+		}
+	}
+
+	gossip_debug(GOSSIP_FILE_DEBUG,
+		     "%s(%pU): Calling post_io_request with tag (%llu)\n",
+		     __func__,
+		     handle,
+		     llu(new_op->tag));
+
+	/* Stage 2: Service the I/O operation */
+	ret = service_operation(new_op,
+				type == ORANGEFS_IO_WRITE ?
+					"file_write" :
+					"file_read",
+				get_interruptible_flag(inode));
+
+	/*
+	 * If service_operation() returns -EAGAIN #and# the operation was
+	 * purged from orangefs_request_list or htable_ops_in_progress, then
+	 * we know that the client was restarted, causing the shared memory
+	 * area to be wiped clean.  To restart a  write operation in this
+	 * case, we must re-copy the data from the user's iovec to a NEW
+	 * shared memory location. To restart a read operation, we must get
+	 * a new shared memory location.
+	 */
+	if (ret == -EAGAIN && op_state_purged(new_op)) {
+		orangefs_bufmap_put(buffer_index);
+		if (type == ORANGEFS_IO_WRITE)
+			iov_iter_revert(iter, total_size);
+		gossip_debug(GOSSIP_FILE_DEBUG,
+			     "%s:going to repopulate_shared_memory.\n",
+			     __func__);
+		goto populate_shared_memory;
+	}
+
+	if (ret < 0) {
+		if (ret == -EINTR) {
+			/*
+			 * We can't return EINTR if any data was written,
+			 * it's not POSIX. It is minimally acceptable
+			 * to give a partial write, the way NFS does.
+			 *
+			 * It would be optimal to return all or nothing,
+			 * but if a userspace write is bigger than
+			 * an IO buffer, and the interrupt occurs
+			 * between buffer writes, that would not be
+			 * possible.
+			 */
+			switch (new_op->op_state - OP_VFS_STATE_GIVEN_UP) {
+			/*
+			 * If the op was waiting when the interrupt
+			 * occurred, then the client-core did not
+			 * trigger the write.
+			 */
+			case OP_VFS_STATE_WAITING:
+				if (*offset == 0)
+					ret = -EINTR;
+				else
+					ret = 0;
+				break;
+			/*
+			 * If the op was in progress when the interrupt
+			 * occurred, then the client-core was able to
+			 * trigger the write.
+			 */
+			case OP_VFS_STATE_INPROGR:
+				if (type == ORANGEFS_IO_READ)
+					ret = -EINTR;
+				else
+					ret = total_size;
+				break;
+			default:
+				gossip_err("%s: unexpected op state :%d:.\n",
+					   __func__,
+					   new_op->op_state);
+				ret = 0;
+				break;
+			}
+			gossip_debug(GOSSIP_FILE_DEBUG,
+				     "%s: got EINTR, state:%d: %p\n",
+				     __func__,
+				     new_op->op_state,
+				     new_op);
+		} else {
+			gossip_err("%s: error in %s handle %pU, returning %zd\n",
+				__func__,
+				type == ORANGEFS_IO_READ ?
+					"read from" : "write to",
+				handle, ret);
+		}
+		if (orangefs_cancel_op_in_progress(new_op))
+			return ret;
+
+		goto out;
+	}
+
+	/*
+	 * Stage 3: Post copy buffers from client-core's address space
+	 */
+	if (type == ORANGEFS_IO_READ && new_op->downcall.resp.io.amt_complete) {
+		/*
+		 * NOTE: the iovector can either contain addresses which
+		 *       can futher be kernel-space or user-space addresses.
+		 *       or it can pointers to struct page's
+		 */
+
+		copy_amount = new_op->downcall.resp.io.amt_complete;
+
+		ret = orangefs_bufmap_copy_to_iovec(iter, buffer_index,
+			copy_amount);
+		if (ret < 0) {
+			gossip_err("%s: Failed to copy-out buffers. Please make sure that the pvfs2-client is running (%ld)\n",
+			    __func__, (long)ret);
+			goto out;
+		}
+	}
+	gossip_debug(GOSSIP_FILE_DEBUG,
+	    "%s(%pU): Amount %s, returned by the sys-io call:%d\n",
+	    __func__,
+	    handle,
+	    type == ORANGEFS_IO_READ ?  "read" : "written",
+	    (int)new_op->downcall.resp.io.amt_complete);
+
+	ret = new_op->downcall.resp.io.amt_complete;
+
+out:
+	if (buffer_index >= 0) {
+		orangefs_bufmap_put(buffer_index);
+		gossip_debug(GOSSIP_FILE_DEBUG,
+			"%s(%pU): PUT buffer_index %d\n",
+			__func__, handle, buffer_index);
+	}
+	op_release(new_op);
+	return ret;
+}
+
+int orangefs_revalidate_mapping(struct inode *inode)
+{
+	struct orangefs_inode_s *orangefs_inode = ORANGEFS_I(inode);
+	struct address_space *mapping = inode->i_mapping;
+	unsigned long *bitlock = &orangefs_inode->bitlock;
+	int ret;
+
+	while (1) {
+		ret = wait_on_bit(bitlock, 1, TASK_KILLABLE);
+		if (ret)
+			return ret;
+		spin_lock(&inode->i_lock);
+		if (test_bit(1, bitlock)) {
+			spin_unlock(&inode->i_lock);
+			continue;
+		}
+		if (!time_before(jiffies, orangefs_inode->mapping_time))
+			break;
+		spin_unlock(&inode->i_lock);
+		return 0;
+	}
+
+	set_bit(1, bitlock);
+	smp_wmb();
+	spin_unlock(&inode->i_lock);
+
+	unmap_mapping_range(mapping, 0, 0, 0);
+	ret = filemap_write_and_wait(mapping);
+	if (!ret)
+		ret = invalidate_inode_pages2(mapping);
+
+	orangefs_inode->mapping_time = jiffies +
+	    orangefs_cache_timeout_msecs*HZ/1000;
+
+	clear_bit(1, bitlock);
+	smp_mb__after_atomic();
+	wake_up_bit(bitlock, 1);
+
+	return ret;
+}
+
+static ssize_t orangefs_file_read_iter(struct kiocb *iocb,
+    struct iov_iter *iter)
+{
+	int ret;
+	orangefs_stats.reads++;
+
+	down_read(&file_inode(iocb->ki_filp)->i_rwsem);
+	ret = orangefs_revalidate_mapping(file_inode(iocb->ki_filp));
+	if (ret)
+		goto out;
+
+	ret = generic_file_read_iter(iocb, iter);
+out:
+	up_read(&file_inode(iocb->ki_filp)->i_rwsem);
+	return ret;
+}
+
+static ssize_t orangefs_file_splice_read(struct file *in, loff_t *ppos,
+					 struct pipe_inode_info *pipe,
+					 size_t len, unsigned int flags)
+{
+	struct inode *inode = file_inode(in);
+	ssize_t ret;
+
+	orangefs_stats.reads++;
+
+	down_read(&inode->i_rwsem);
+	ret = orangefs_revalidate_mapping(inode);
+	if (ret)
+		goto out;
+
+	ret = filemap_splice_read(in, ppos, pipe, len, flags);
+out:
+	up_read(&inode->i_rwsem);
+	return ret;
+}
+
+static ssize_t orangefs_file_write_iter(struct kiocb *iocb,
+    struct iov_iter *iter)
+{
+	int ret;
+	orangefs_stats.writes++;
+
+	if (iocb->ki_pos > i_size_read(file_inode(iocb->ki_filp))) {
+		ret = orangefs_revalidate_mapping(file_inode(iocb->ki_filp));
+		if (ret)
+			return ret;
+	}
+
+	ret = generic_file_write_iter(iocb, iter);
+	return ret;
+}
+
+static vm_fault_t orangefs_fault(struct vm_fault *vmf)
+{
+	struct file *file = vmf->vma->vm_file;
+	int ret;
+	ret = orangefs_inode_getattr(file->f_mapping->host,
+	    ORANGEFS_GETATTR_SIZE);
+	if (ret == -ESTALE)
+		ret = -EIO;
+	if (ret) {
+		gossip_err("%s: orangefs_inode_getattr failed, "
+		    "ret:%d:.\n", __func__, ret);
+		return VM_FAULT_SIGBUS;
+	}
+	return filemap_fault(vmf);
+}
+
+static const struct vm_operations_struct orangefs_file_vm_ops = {
+	.fault = orangefs_fault,
+	.map_pages = filemap_map_pages,
+	.page_mkwrite = orangefs_page_mkwrite,
+};
+
+/*
+ * Memory map a region of a file.
+ */
+static int orangefs_file_mmap_prepare(struct vm_area_desc *desc)
+{
+	struct file *file = desc->file;
+	int ret;
+
+	ret = orangefs_revalidate_mapping(file_inode(file));
+	if (ret)
+		return ret;
+
+	gossip_debug(GOSSIP_FILE_DEBUG,
+		     "orangefs_file_mmap: called on %pD\n", file);
+
+	/* set the sequential readahead hint */
+	vma_desc_set_flags(desc, VMA_SEQ_READ_BIT);
+	vma_desc_clear_flags(desc, VMA_RAND_READ_BIT);
+
+	file_accessed(file);
+	desc->vm_ops = &orangefs_file_vm_ops;
+	return 0;
+}
+
+#define mapping_nrpages(idata) ((idata)->nrpages)
+
+/*
+ * Called to notify the module that there are no more references to
+ * this file (i.e. no processes have it open).
+ *
+ * \note Not called when each file is closed.
+ */
+static int orangefs_file_release(struct inode *inode, struct file *file)
+{
+	gossip_debug(GOSSIP_FILE_DEBUG,
+		     "orangefs_file_release: called on %pD\n",
+		     file);
+
+	/*
+	 * remove all associated inode pages from the page cache and
+	 * readahead cache (if any); this forces an expensive refresh of
+	 * data for the next caller of mmap (or 'get_block' accesses)
+	 */
+	if (mapping_nrpages(file->f_mapping)) {
+		if (orangefs_features & ORANGEFS_FEATURE_READAHEAD) {
+			gossip_debug(GOSSIP_INODE_DEBUG,
+			    "calling flush_racache on %pU\n",
+			    get_khandle_from_ino(inode));
+			flush_racache(inode);
+			gossip_debug(GOSSIP_INODE_DEBUG,
+			    "flush_racache finished\n");
+		}
+
+	}
+	return 0;
+}
+
+/*
+ * Push all data for a specific file onto permanent storage.
+ */
+static int orangefs_fsync(struct file *file,
+		       loff_t start,
+		       loff_t end,
+		       int datasync)
+{
+	int ret;
+	struct orangefs_inode_s *orangefs_inode =
+		ORANGEFS_I(file_inode(file));
+	struct orangefs_kernel_op_s *new_op = NULL;
+
+	ret = filemap_write_and_wait_range(file_inode(file)->i_mapping,
+	    start, end);
+	if (ret < 0)
+		return ret;
+
+	new_op = op_alloc(ORANGEFS_VFS_OP_FSYNC);
+	if (!new_op)
+		return -ENOMEM;
+	new_op->upcall.req.fsync.refn = orangefs_inode->refn;
+
+	ret = service_operation(new_op,
+			"orangefs_fsync",
+			get_interruptible_flag(file_inode(file)));
+
+	gossip_debug(GOSSIP_FILE_DEBUG,
+		     "orangefs_fsync got return value of %d\n",
+		     ret);
+
+	op_release(new_op);
+	return ret;
+}
+
+/*
+ * Change the file pointer position for an instance of an open file.
+ *
+ * \note If .llseek is overriden, we must acquire lock as described in
+ *       Documentation/filesystems/locking.rst.
+ *
+ * Future upgrade could support SEEK_DATA and SEEK_HOLE but would
+ * require much changes to the FS
+ */
+static loff_t orangefs_file_llseek(struct file *file, loff_t offset, int origin)
+{
+	int ret = -EINVAL;
+	struct inode *inode = file_inode(file);
+
+	if (origin == SEEK_END) {
+		/*
+		 * revalidate the inode's file size.
+		 * NOTE: We are only interested in file size here,
+		 * so we set mask accordingly.
+		 */
+		ret = orangefs_inode_getattr(file->f_mapping->host,
+		    ORANGEFS_GETATTR_SIZE);
+		if (ret == -ESTALE)
+			ret = -EIO;
+		if (ret) {
+			gossip_debug(GOSSIP_FILE_DEBUG,
+				     "%s:%s:%d calling make bad inode\n",
+				     __FILE__,
+				     __func__,
+				     __LINE__);
+			return ret;
+		}
+	}
+
+	gossip_debug(GOSSIP_FILE_DEBUG,
+		     "orangefs_file_llseek: offset is %ld | origin is %d"
+		     " | inode size is %lu\n",
+		     (long)offset,
+		     origin,
+		     (unsigned long)i_size_read(inode));
+
+	return generic_file_llseek(file, offset, origin);
+}
+
+/*
+ * Support local locks (locks that only this kernel knows about)
+ * if Orangefs was mounted -o local_lock.
+ */
+static int orangefs_lock(struct file *filp, int cmd, struct file_lock *fl)
+{
+	int rc = -EINVAL;
+
+	if (ORANGEFS_SB(file_inode(filp)->i_sb)->flags & ORANGEFS_OPT_LOCAL_LOCK) {
+		if (cmd == F_GETLK) {
+			rc = 0;
+			posix_test_lock(filp, fl);
+		} else {
+			rc = posix_lock_file(filp, fl, NULL);
+		}
+	}
+
+	return rc;
+}
+
+static int orangefs_flush(struct file *file, fl_owner_t id)
+{
+	/*
+	 * This is vfs_fsync_range(file, 0, LLONG_MAX, 0) without the
+	 * service_operation in orangefs_fsync.
+	 *
+	 * Do not send fsync to OrangeFS server on a close.  Do send fsync
+	 * on an explicit fsync call.  This duplicates historical OrangeFS
+	 * behavior.
+	 */
+	int r;
+
+	r = filemap_write_and_wait_range(file->f_mapping, 0, LLONG_MAX);
+	if (r > 0)
+		return 0;
+	else
+		return r;
+}
+
+/** ORANGEFS implementation of VFS file operations */
+const struct file_operations orangefs_file_operations = {
+	.llseek		= orangefs_file_llseek,
+	.read_iter	= orangefs_file_read_iter,
+	.write_iter	= orangefs_file_write_iter,
+	.lock		= orangefs_lock,
+	.mmap_prepare	= orangefs_file_mmap_prepare,
+	.open		= generic_file_open,
+	.splice_read    = orangefs_file_splice_read,
+	.splice_write   = iter_file_splice_write,
+	.flush		= orangefs_flush,
+	.release	= orangefs_file_release,
+	.fsync		= orangefs_fsync,
+	.setlease	= generic_setlease,
+};