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, 446 insertions, 0 deletions

diff --git a/fs/fuse/notify.c b/fs/fuse/notify.c
new file mode 100644
index 000000000..1ba763705
--- /dev/null
+++ b/fs/fuse/notify.c
@@ -0,0 +1,446 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+#include "dev.h"
+#include "fuse_i.h"
+
+#include <linux/iomap.h>
+#include <linux/pagemap.h>
+
+static int fuse_notify_poll(struct fuse_conn *fc, unsigned int size,
+			    struct fuse_copy_state *cs)
+{
+	struct fuse_notify_poll_wakeup_out outarg;
+	int err;
+
+	if (size != sizeof(outarg))
+		return -EINVAL;
+
+	err = fuse_copy_one(cs, &outarg, sizeof(outarg));
+	if (err)
+		return err;
+
+	fuse_copy_finish(cs);
+	return fuse_notify_poll_wakeup(fc, &outarg);
+}
+
+static int fuse_notify_inval_inode(struct fuse_conn *fc, unsigned int size,
+				   struct fuse_copy_state *cs)
+{
+	struct fuse_notify_inval_inode_out outarg;
+	int err;
+
+	if (size != sizeof(outarg))
+		return -EINVAL;
+
+	err = fuse_copy_one(cs, &outarg, sizeof(outarg));
+	if (err)
+		return err;
+	fuse_copy_finish(cs);
+
+	down_read(&fc->killsb);
+	err = fuse_reverse_inval_inode(fc, outarg.ino,
+				       outarg.off, outarg.len);
+	up_read(&fc->killsb);
+	return err;
+}
+
+static int fuse_notify_inval_entry(struct fuse_conn *fc, unsigned int size,
+				   struct fuse_copy_state *cs)
+{
+	struct fuse_notify_inval_entry_out outarg;
+	int err;
+	char *buf;
+	struct qstr name;
+
+	if (size < sizeof(outarg))
+		return -EINVAL;
+
+	err = fuse_copy_one(cs, &outarg, sizeof(outarg));
+	if (err)
+		return err;
+
+	if (outarg.namelen > fc->name_max)
+		return -ENAMETOOLONG;
+
+	err = -EINVAL;
+	if (size != sizeof(outarg) + outarg.namelen + 1)
+		return -EINVAL;
+
+	buf = kzalloc(outarg.namelen + 1, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
+	name.name = buf;
+	name.len = outarg.namelen;
+	err = fuse_copy_one(cs, buf, outarg.namelen + 1);
+	if (err)
+		goto err;
+	fuse_copy_finish(cs);
+	buf[outarg.namelen] = 0;
+
+	down_read(&fc->killsb);
+	err = fuse_reverse_inval_entry(fc, outarg.parent, 0, &name, outarg.flags);
+	up_read(&fc->killsb);
+err:
+	kfree(buf);
+	return err;
+}
+
+static int fuse_notify_delete(struct fuse_conn *fc, unsigned int size,
+			      struct fuse_copy_state *cs)
+{
+	struct fuse_notify_delete_out outarg;
+	int err;
+	char *buf;
+	struct qstr name;
+
+	if (size < sizeof(outarg))
+		return -EINVAL;
+
+	err = fuse_copy_one(cs, &outarg, sizeof(outarg));
+	if (err)
+		return err;
+
+	if (outarg.namelen > fc->name_max)
+		return -ENAMETOOLONG;
+
+	if (size != sizeof(outarg) + outarg.namelen + 1)
+		return -EINVAL;
+
+	buf = kzalloc(outarg.namelen + 1, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
+	name.name = buf;
+	name.len = outarg.namelen;
+	err = fuse_copy_one(cs, buf, outarg.namelen + 1);
+	if (err)
+		goto err;
+	fuse_copy_finish(cs);
+	buf[outarg.namelen] = 0;
+
+	down_read(&fc->killsb);
+	err = fuse_reverse_inval_entry(fc, outarg.parent, outarg.child, &name, 0);
+	up_read(&fc->killsb);
+err:
+	kfree(buf);
+	return err;
+}
+
+static int fuse_notify_store(struct fuse_conn *fc, unsigned int size,
+			     struct fuse_copy_state *cs)
+{
+	struct fuse_notify_store_out outarg;
+	struct inode *inode;
+	struct address_space *mapping;
+	u64 nodeid;
+	int err;
+	unsigned int num;
+	loff_t file_size;
+	loff_t pos;
+	loff_t end;
+
+	if (size < sizeof(outarg))
+		return -EINVAL;
+
+	err = fuse_copy_one(cs, &outarg, sizeof(outarg));
+	if (err)
+		return err;
+
+	if (size - sizeof(outarg) != outarg.size)
+		return -EINVAL;
+
+	if (outarg.offset >= MAX_LFS_FILESIZE)
+		return -EINVAL;
+
+	nodeid = outarg.nodeid;
+	pos = outarg.offset;
+	num = min(outarg.size, MAX_LFS_FILESIZE - pos);
+
+	down_read(&fc->killsb);
+
+	err = -ENOENT;
+	inode = fuse_ilookup(fc, nodeid,  NULL);
+	if (!inode)
+		goto out_up_killsb;
+	if (!S_ISREG(inode->i_mode)) {
+		err = -EINVAL;
+		goto out_iput;
+	}
+
+	mapping = inode->i_mapping;
+	file_size = i_size_read(inode);
+	end = pos + num;
+	if (end > file_size) {
+		file_size = end;
+		fuse_write_update_attr(inode, file_size, num);
+	}
+
+	while (num) {
+		struct folio *folio;
+		unsigned int folio_offset;
+		unsigned int nr_bytes;
+		pgoff_t index = pos >> PAGE_SHIFT;
+
+		folio = filemap_grab_folio(mapping, index);
+		err = PTR_ERR(folio);
+		if (IS_ERR(folio))
+			goto out_iput;
+
+		folio_offset = offset_in_folio(folio, pos);
+		nr_bytes = min(num, folio_size(folio) - folio_offset);
+
+		err = fuse_copy_folio(cs, &folio, folio_offset, nr_bytes, 0);
+		if (!folio_test_uptodate(folio) && !err && folio_offset == 0 &&
+		    (nr_bytes == folio_size(folio) || file_size == end)) {
+			folio_zero_segment(folio, nr_bytes, folio_size(folio));
+			iomap_folio_mark_uptodate(folio);
+		}
+		folio_unlock(folio);
+		folio_put(folio);
+
+		if (err)
+			goto out_iput;
+
+		pos += nr_bytes;
+		num -= nr_bytes;
+	}
+
+	err = 0;
+
+out_iput:
+	iput(inode);
+out_up_killsb:
+	up_read(&fc->killsb);
+	return err;
+}
+
+struct fuse_retrieve_args {
+	struct fuse_args_pages ap;
+	struct fuse_notify_retrieve_in inarg;
+};
+
+static void fuse_retrieve_end(struct fuse_args *args, int error)
+{
+	struct fuse_retrieve_args *ra =
+		container_of(args, typeof(*ra), ap.args);
+
+	release_pages(ra->ap.folios, ra->ap.num_folios);
+	kfree(ra);
+}
+
+static int fuse_retrieve(struct fuse_mount *fm, struct inode *inode,
+			 struct fuse_notify_retrieve_out *outarg)
+{
+	int err;
+	struct address_space *mapping = inode->i_mapping;
+	loff_t file_size;
+	unsigned int num;
+	unsigned int offset;
+	size_t total_len = 0;
+	unsigned int num_pages;
+	struct fuse_conn *fc = fm->fc;
+	struct fuse_retrieve_args *ra;
+	size_t args_size = sizeof(*ra);
+	struct fuse_args_pages *ap;
+	struct fuse_args *args;
+	loff_t pos = outarg->offset;
+
+	offset = offset_in_page(pos);
+	file_size = i_size_read(inode);
+
+	num = min(outarg->size, fc->max_write);
+	if (pos > file_size)
+		num = 0;
+	else if (num > file_size - pos)
+		num = file_size - pos;
+
+	num_pages = DIV_ROUND_UP(num + offset, PAGE_SIZE);
+	num_pages = min(num_pages, fc->max_pages);
+	num = min(num, num_pages << PAGE_SHIFT);
+
+	args_size += num_pages * (sizeof(ap->folios[0]) + sizeof(ap->descs[0]));
+
+	ra = kzalloc(args_size, GFP_KERNEL);
+	if (!ra)
+		return -ENOMEM;
+
+	ap = &ra->ap;
+	ap->folios = (void *) (ra + 1);
+	ap->descs = (void *) (ap->folios + num_pages);
+
+	args = &ap->args;
+	args->nodeid = outarg->nodeid;
+	args->opcode = FUSE_NOTIFY_REPLY;
+	args->in_numargs = 3;
+	args->in_pages = true;
+	args->end = fuse_retrieve_end;
+
+	while (num && ap->num_folios < num_pages) {
+		struct folio *folio;
+		unsigned int folio_offset;
+		unsigned int nr_bytes;
+		pgoff_t index = pos >> PAGE_SHIFT;
+
+		folio = filemap_get_folio(mapping, index);
+		if (IS_ERR(folio))
+			break;
+		if (!folio_test_uptodate(folio)) {
+			folio_put(folio);
+			break;
+		}
+
+		folio_offset = offset_in_folio(folio, pos);
+		nr_bytes = min(folio_size(folio) - folio_offset, num);
+
+		ap->folios[ap->num_folios] = folio;
+		ap->descs[ap->num_folios].offset = folio_offset;
+		ap->descs[ap->num_folios].length = nr_bytes;
+		ap->num_folios++;
+
+		pos += nr_bytes;
+		num -= nr_bytes;
+		total_len += nr_bytes;
+	}
+	ra->inarg.offset = outarg->offset;
+	ra->inarg.size = total_len;
+	fuse_set_zero_arg0(args);
+	args->in_args[1].size = sizeof(ra->inarg);
+	args->in_args[1].value = &ra->inarg;
+	args->in_args[2].size = total_len;
+
+	err = fuse_simple_notify_reply(fm, args, outarg->notify_unique);
+	if (err)
+		fuse_retrieve_end(args, err);
+
+	return err;
+}
+
+static int fuse_notify_retrieve(struct fuse_conn *fc, unsigned int size,
+				struct fuse_copy_state *cs)
+{
+	struct fuse_notify_retrieve_out outarg;
+	struct fuse_mount *fm;
+	struct inode *inode;
+	u64 nodeid;
+	int err;
+
+	if (size != sizeof(outarg))
+		return -EINVAL;
+
+	err = fuse_copy_one(cs, &outarg, sizeof(outarg));
+	if (err)
+		return err;
+
+	fuse_copy_finish(cs);
+
+	if (outarg.offset >= MAX_LFS_FILESIZE)
+		return -EINVAL;
+
+	down_read(&fc->killsb);
+	err = -ENOENT;
+	nodeid = outarg.nodeid;
+
+	inode = fuse_ilookup(fc, nodeid, &fm);
+	if (inode) {
+		err = -EINVAL;
+		if (S_ISREG(inode->i_mode))
+			err = fuse_retrieve(fm, inode, &outarg);
+		iput(inode);
+	}
+	up_read(&fc->killsb);
+
+	return err;
+}
+
+static int fuse_notify_resend(struct fuse_conn *fc)
+{
+	fuse_chan_resend(fc->chan);
+	return 0;
+}
+
+/*
+ * Increments the fuse connection epoch.  This will cause dentries and
+ * readdir caches from previous epochs to be invalidated.  Additionally,
+ * if inval_wq is set, a work queue is scheduled to trigger the invalidation.
+ */
+static int fuse_notify_inc_epoch(struct fuse_conn *fc)
+{
+	atomic_inc(&fc->epoch);
+	if (inval_wq)
+		schedule_work(&fc->epoch_work);
+
+	return 0;
+}
+
+static int fuse_notify_prune(struct fuse_conn *fc, unsigned int size,
+			     struct fuse_copy_state *cs)
+{
+	struct fuse_notify_prune_out outarg;
+	const unsigned int batch = 512;
+	u64 *nodeids __free(kfree) = kmalloc(sizeof(u64) * batch, GFP_KERNEL);
+	unsigned int num, i;
+	int err;
+
+	if (!nodeids)
+		return -ENOMEM;
+
+	if (size < sizeof(outarg))
+		return -EINVAL;
+
+	err = fuse_copy_one(cs, &outarg, sizeof(outarg));
+	if (err)
+		return err;
+
+	if (size - sizeof(outarg) != array_size(outarg.count, sizeof(u64)))
+		return -EINVAL;
+
+	for (; outarg.count; outarg.count -= num) {
+		num = min(batch, outarg.count);
+		err = fuse_copy_one(cs, nodeids, num * sizeof(u64));
+		if (err)
+			return err;
+
+		scoped_guard(rwsem_read, &fc->killsb) {
+			for (i = 0; i < num; i++)
+				fuse_try_prune_one_inode(fc, nodeids[i]);
+		}
+	}
+	return 0;
+}
+
+int fuse_notify(struct fuse_conn *fc, enum fuse_notify_code code,
+		unsigned int size, struct fuse_copy_state *cs)
+{
+	switch (code) {
+	case FUSE_NOTIFY_POLL:
+		return fuse_notify_poll(fc, size, cs);
+
+	case FUSE_NOTIFY_INVAL_INODE:
+		return fuse_notify_inval_inode(fc, size, cs);
+
+	case FUSE_NOTIFY_INVAL_ENTRY:
+		return fuse_notify_inval_entry(fc, size, cs);
+
+	case FUSE_NOTIFY_STORE:
+		return fuse_notify_store(fc, size, cs);
+
+	case FUSE_NOTIFY_RETRIEVE:
+		return fuse_notify_retrieve(fc, size, cs);
+
+	case FUSE_NOTIFY_DELETE:
+		return fuse_notify_delete(fc, size, cs);
+
+	case FUSE_NOTIFY_RESEND:
+		return fuse_notify_resend(fc);
+
+	case FUSE_NOTIFY_INC_EPOCH:
+		return fuse_notify_inc_epoch(fc);
+
+	case FUSE_NOTIFY_PRUNE:
+		return fuse_notify_prune(fc, size, cs);
+
+	default:
+		return -EINVAL;
+	}
+}