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, 73 insertions, 0 deletions

diff --git a/fs/jffs2/security.c b/fs/jffs2/security.c
new file mode 100644
index 000000000..437f3a2c1
--- /dev/null
+++ b/fs/jffs2/security.c
@@ -0,0 +1,73 @@
+/*
+ * JFFS2 -- Journalling Flash File System, Version 2.
+ *
+ * Copyright © 2006  NEC Corporation
+ *
+ * Created by KaiGai Kohei <kaigai@ak.jp.nec.com>
+ *
+ * For licensing information, see the file 'LICENCE' in this directory.
+ *
+ */
+
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/fs.h>
+#include <linux/time.h>
+#include <linux/pagemap.h>
+#include <linux/highmem.h>
+#include <linux/crc32.h>
+#include <linux/jffs2.h>
+#include <linux/xattr.h>
+#include <linux/mtd/mtd.h>
+#include <linux/security.h>
+#include "nodelist.h"
+
+/* ---- Initial Security Label(s) Attachment callback --- */
+static int jffs2_initxattrs(struct inode *inode,
+			    const struct xattr *xattr_array, void *fs_info)
+{
+	const struct xattr *xattr;
+	int err = 0;
+
+	for (xattr = xattr_array; xattr->name != NULL; xattr++) {
+		err = do_jffs2_setxattr(inode, JFFS2_XPREFIX_SECURITY,
+					xattr->name, xattr->value,
+					xattr->value_len, 0);
+		if (err < 0)
+			break;
+	}
+	return err;
+}
+
+/* ---- Initial Security Label(s) Attachment ----------- */
+int jffs2_init_security(struct inode *inode, struct inode *dir,
+			const struct qstr *qstr)
+{
+	return security_inode_init_security(inode, dir, qstr,
+					    &jffs2_initxattrs, NULL);
+}
+
+/* ---- XATTR Handler for "security.*" ----------------- */
+static int jffs2_security_getxattr(const struct xattr_handler *handler,
+				   struct dentry *unused, struct inode *inode,
+				   const char *name, void *buffer, size_t size)
+{
+	return do_jffs2_getxattr(inode, JFFS2_XPREFIX_SECURITY,
+				 name, buffer, size);
+}
+
+static int jffs2_security_setxattr(const struct xattr_handler *handler,
+				   struct mnt_idmap *idmap,
+				   struct dentry *unused, struct inode *inode,
+				   const char *name, const void *buffer,
+				   size_t size, int flags)
+{
+	return do_jffs2_setxattr(inode, JFFS2_XPREFIX_SECURITY,
+				 name, buffer, size, flags);
+}
+
+const struct xattr_handler jffs2_security_xattr_handler = {
+	.prefix = XATTR_SECURITY_PREFIX,
+	.set = jffs2_security_setxattr,
+	.get = jffs2_security_getxattr
+};