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, 79 insertions, 0 deletions

diff --git a/fs/hfsplus/xattr_security.c b/fs/hfsplus/xattr_security.c
new file mode 100644
index 000000000..90f68ec11
--- /dev/null
+++ b/fs/hfsplus/xattr_security.c
@@ -0,0 +1,79 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * linux/fs/hfsplus/xattr_trusted.c
+ *
+ * Vyacheslav Dubeyko <slava@dubeyko.com>
+ *
+ * Handler for storing security labels as extended attributes.
+ */
+
+#include <linux/security.h>
+#include <linux/nls.h>
+
+#include "hfsplus_fs.h"
+#include "xattr.h"
+
+static int hfsplus_security_getxattr(const struct xattr_handler *handler,
+				     struct dentry *unused, struct inode *inode,
+				     const char *name, void *buffer, size_t size)
+{
+	return hfsplus_getxattr(inode, name, buffer, size,
+				XATTR_SECURITY_PREFIX,
+				XATTR_SECURITY_PREFIX_LEN);
+}
+
+static int hfsplus_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 hfsplus_setxattr(inode, name, buffer, size, flags,
+				XATTR_SECURITY_PREFIX,
+				XATTR_SECURITY_PREFIX_LEN);
+}
+
+static int hfsplus_initxattrs(struct inode *inode,
+				const struct xattr *xattr_array,
+				void *fs_info)
+{
+	const struct xattr *xattr;
+	char *xattr_name;
+	int err = 0;
+
+	xattr_name = kmalloc(NLS_MAX_CHARSET_SIZE * HFSPLUS_ATTR_MAX_STRLEN + 1,
+		GFP_KERNEL);
+	if (!xattr_name)
+		return -ENOMEM;
+	for (xattr = xattr_array; xattr->name != NULL; xattr++) {
+
+		if (!strcmp(xattr->name, ""))
+			continue;
+
+		strcpy(xattr_name, XATTR_SECURITY_PREFIX);
+		strcpy(xattr_name +
+			XATTR_SECURITY_PREFIX_LEN, xattr->name);
+		memset(xattr_name +
+			XATTR_SECURITY_PREFIX_LEN + strlen(xattr->name), 0, 1);
+
+		err = __hfsplus_setxattr(inode, xattr_name,
+					xattr->value, xattr->value_len, 0);
+		if (err)
+			break;
+	}
+	kfree(xattr_name);
+	return err;
+}
+
+int hfsplus_init_security(struct inode *inode, struct inode *dir,
+				const struct qstr *qstr)
+{
+	return security_inode_init_security(inode, dir, qstr,
+					&hfsplus_initxattrs, NULL);
+}
+
+const struct xattr_handler hfsplus_xattr_security_handler = {
+	.prefix	= XATTR_SECURITY_PREFIX,
+	.get	= hfsplus_security_getxattr,
+	.set	= hfsplus_security_setxattr,
+};