ftrace: Synchronize the initialization of ftrace_opsgrafted

There's some internal state that ftrace_ops needs to have set, but since
it can be declared outside of the ftrace.c code, it calls
ftrace_ops_init() on the ops in every global function. The issue is that
if two tasks call it on the same ops at the same time it is possible to
have the initialization of one corrupt the initialization of the other
call.

Create a ops_mutex to use to synchronize every initialization of the
ftrace_ops. The mutex is taken within checking the ftrace_ops flag that
states it was initializied but the flag is checked again after the mutex
has been taken. Checking first outside the mutex allows it to shortcut
having to take the mutex. But then the check needs to be done again after
the mute is taken in case of races.

Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260902095501.6b59af20@gandalf.local.home
Fixes: f04f24fb7e48d ("ftrace, kprobes: Fix a deadlock on ftrace_regex_lock")
Reported-by: sashiko-bot@kernel.org
Close: https://lore.kernel.org/all/20260829025528.49A831F000E9@smtp.kernel.org/
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

1 files changed, 159 insertions, 0 deletions

diff --git a/fs/ext2/ioctl.c b/fs/ext2/ioctl.c
new file mode 100644
index 000000000..c3fea55b8
--- /dev/null
+++ b/fs/ext2/ioctl.c
@@ -0,0 +1,159 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * linux/fs/ext2/ioctl.c
+ *
+ * Copyright (C) 1993, 1994, 1995
+ * Remy Card (card@masi.ibp.fr)
+ * Laboratoire MASI - Institut Blaise Pascal
+ * Universite Pierre et Marie Curie (Paris VI)
+ */
+
+#include "ext2.h"
+#include <linux/capability.h>
+#include <linux/time.h>
+#include <linux/sched.h>
+#include <linux/compat.h>
+#include <linux/mount.h>
+#include <asm/current.h>
+#include <linux/uaccess.h>
+#include <linux/fileattr.h>
+
+int ext2_fileattr_get(struct dentry *dentry, struct file_kattr *fa)
+{
+	struct ext2_inode_info *ei = EXT2_I(d_inode(dentry));
+
+	fileattr_fill_flags(fa, ei->i_flags & EXT2_FL_USER_VISIBLE);
+
+	return 0;
+}
+
+int ext2_fileattr_set(struct mnt_idmap *idmap,
+		      struct dentry *dentry, struct file_kattr *fa)
+{
+	struct inode *inode = d_inode(dentry);
+	struct ext2_inode_info *ei = EXT2_I(inode);
+
+	if (fileattr_has_fsx(fa))
+		return -EOPNOTSUPP;
+
+	/* Is it quota file? Do not allow user to mess with it */
+	if (IS_NOQUOTA(inode))
+		return -EPERM;
+
+	ei->i_flags = (ei->i_flags & ~EXT2_FL_USER_MODIFIABLE) |
+		(fa->flags & EXT2_FL_USER_MODIFIABLE);
+
+	ext2_set_inode_flags(inode);
+	inode_set_ctime_current(inode);
+	mark_inode_dirty(inode);
+
+	return 0;
+}
+
+
+long ext2_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
+{
+	struct inode *inode = file_inode(filp);
+	struct ext2_inode_info *ei = EXT2_I(inode);
+	unsigned short rsv_window_size;
+	int ret;
+
+	ext2_debug ("cmd = %u, arg = %lu\n", cmd, arg);
+
+	switch (cmd) {
+	case EXT2_IOC_GETVERSION:
+		return put_user(inode->i_generation, (int __user *) arg);
+	case EXT2_IOC_SETVERSION: {
+		__u32 generation;
+
+		if (!inode_owner_or_capable(&nop_mnt_idmap, inode))
+			return -EPERM;
+		ret = mnt_want_write_file(filp);
+		if (ret)
+			return ret;
+		if (get_user(generation, (int __user *) arg)) {
+			ret = -EFAULT;
+			goto setversion_out;
+		}
+
+		inode_lock(inode);
+		inode_set_ctime_current(inode);
+		inode->i_generation = generation;
+		inode_unlock(inode);
+
+		mark_inode_dirty(inode);
+setversion_out:
+		mnt_drop_write_file(filp);
+		return ret;
+	}
+	case EXT2_IOC_GETRSVSZ:
+		if (test_opt(inode->i_sb, RESERVATION)
+			&& S_ISREG(inode->i_mode)
+			&& ei->i_block_alloc_info) {
+			rsv_window_size = ei->i_block_alloc_info->rsv_window_node.rsv_goal_size;
+			return put_user(rsv_window_size, (int __user *)arg);
+		}
+		return -ENOTTY;
+	case EXT2_IOC_SETRSVSZ: {
+
+		if (!test_opt(inode->i_sb, RESERVATION) ||!S_ISREG(inode->i_mode))
+			return -ENOTTY;
+
+		if (!inode_owner_or_capable(&nop_mnt_idmap, inode))
+			return -EACCES;
+
+		if (get_user(rsv_window_size, (int __user *)arg))
+			return -EFAULT;
+
+		ret = mnt_want_write_file(filp);
+		if (ret)
+			return ret;
+
+		if (rsv_window_size > EXT2_MAX_RESERVE_BLOCKS)
+			rsv_window_size = EXT2_MAX_RESERVE_BLOCKS;
+
+		/*
+		 * need to allocate reservation structure for this inode
+		 * before set the window size
+		 */
+		/*
+		 * XXX What lock should protect the rsv_goal_size?
+		 * Accessed in ext2_get_block only.  ext3 uses i_truncate.
+		 */
+		mutex_lock(&ei->truncate_mutex);
+		if (!ei->i_block_alloc_info)
+			ext2_init_block_alloc_info(inode);
+
+		if (ei->i_block_alloc_info){
+			struct ext2_reserve_window_node *rsv = &ei->i_block_alloc_info->rsv_window_node;
+			rsv->rsv_goal_size = rsv_window_size;
+		} else {
+			ret = -ENOMEM;
+		}
+
+		mutex_unlock(&ei->truncate_mutex);
+		mnt_drop_write_file(filp);
+		return ret;
+	}
+	default:
+		return -ENOTTY;
+	}
+}
+
+#ifdef CONFIG_COMPAT
+long ext2_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
+{
+	/* These are just misnamed, they actually get/put from/to user an int */
+	switch (cmd) {
+	case EXT2_IOC32_GETVERSION:
+		cmd = EXT2_IOC_GETVERSION;
+		break;
+	case EXT2_IOC32_SETVERSION:
+		cmd = EXT2_IOC_SETVERSION;
+		break;
+	default:
+		return -ENOIOCTLCMD;
+	}
+	return ext2_ioctl(file, cmd, (unsigned long) compat_ptr(arg));
+}
+#endif