From: Joanne Koong <joannelkoong@gmail.com>
Date: Wed, 22 Apr 2026 16:31:23 +0000 (-0700)
Subject: fuse: don't block in fuse_get_dev() for non-sync_init case
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=9f6f44aa5a58aaae0838126dc09460c3e1f56ccb;p=thirdparty%2Flinux.git

fuse: don't block in fuse_get_dev() for non-sync_init case

Commit a8dd5f1b73bc ("fuse: create fuse_dev on /dev/fuse open instead of
mount") changed behavior so that fuse_get_dev() now unconditionally
blocks waiting for a connection, even in the case where sync_init was
not set. Previously, non-sync_init opens returned -EPERM immediately.

Restore the previous behavior of returning -EPERM.

Fixes: a8dd5f1b73bc ("fuse: create fuse_dev on /dev/fuse open instead of mount")
Reported-by: Mark Brown <broonie@kernel.org>
Closes: https://lore.kernel.org/all/3c9f8396-41f4-4c88-b883-34bede72b427@sirena.org.uk/
Cc: <stable@vger.kernel.org>
Signed-off-by: Joanne Koong <joannelkoong@gmail.com>
Tested-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
---

diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c
index 5dda7080f4a90..05b6d15afe61e 100644
--- a/fs/fuse/dev.c
+++ b/fs/fuse/dev.c
@@ -1562,9 +1562,15 @@ struct fuse_dev *fuse_get_dev(struct file *file)
 	struct fuse_dev *fud = fuse_file_to_fud(file);
 	int err;
 
-	err = wait_event_interruptible(fuse_dev_waitq, fuse_dev_fc_get(fud) != NULL);
-	if (err)
-		return ERR_PTR(err);
+	if (unlikely(!fuse_dev_fc_get(fud))) {
+		/* only block waiting for mount if sync init was requested */
+		if (!fud->sync_init)
+			return ERR_PTR(-EPERM);
+
+		err = wait_event_interruptible(fuse_dev_waitq, fuse_dev_fc_get(fud) != NULL);
+		if (err)
+			return ERR_PTR(err);
+	}
 
 	return fud;
 }