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, 70 insertions, 0 deletions

diff --git a/fs/hfsplus/ioctl.c b/fs/hfsplus/ioctl.c
new file mode 100644
index 000000000..40d04dba1
--- /dev/null
+++ b/fs/hfsplus/ioctl.c
@@ -0,0 +1,70 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ *  linux/fs/hfsplus/ioctl.c
+ *
+ * Copyright (C) 2003
+ * Ethan Benson <erbenson@alaska.net>
+ * partially derived from 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)
+ *
+ * hfsplus ioctls
+ */
+
+#include <linux/capability.h>
+#include <linux/fs.h>
+#include <linux/mount.h>
+#include <linux/sched.h>
+#include <linux/uaccess.h>
+#include "hfsplus_fs.h"
+
+/*
+ * "Blessing" an HFS+ filesystem writes metadata to the superblock informing
+ * the platform firmware which file to boot from
+ */
+static int hfsplus_ioctl_bless(struct file *file, int __user *user_flags)
+{
+	struct dentry *dentry = file->f_path.dentry;
+	struct inode *inode = d_inode(dentry);
+	struct hfsplus_sb_info *sbi = HFSPLUS_SB(inode->i_sb);
+	struct hfsplus_vh *vh = sbi->s_vhdr;
+	struct hfsplus_vh *bvh = sbi->s_backup_vhdr;
+	u32 cnid = (unsigned long)dentry->d_fsdata;
+
+	if (!capable(CAP_SYS_ADMIN))
+		return -EPERM;
+
+	mutex_lock(&sbi->vh_mutex);
+
+	/* Directory containing the bootable system */
+	vh->finder_info[0] = bvh->finder_info[0] =
+		cpu_to_be32(d_parent_ino(dentry));
+
+	/*
+	 * Bootloader. Just using the inode here breaks in the case of
+	 * hard links - the firmware wants the ID of the hard link file,
+	 * but the inode points at the indirect inode
+	 */
+	vh->finder_info[1] = bvh->finder_info[1] = cpu_to_be32(cnid);
+
+	/* Per spec, the OS X system folder - same as finder_info[0] here */
+	vh->finder_info[5] = bvh->finder_info[5] =
+		cpu_to_be32(d_parent_ino(dentry));
+
+	mutex_unlock(&sbi->vh_mutex);
+	return 0;
+}
+
+long hfsplus_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
+{
+	void __user *argp = (void __user *)arg;
+
+	switch (cmd) {
+	case HFSPLUS_IOC_BLESS:
+		return hfsplus_ioctl_bless(file, argp);
+	default:
+		return -ENOTTY;
+	}
+}