From cfb2abd23631abff4d7feb0291f320c98c8dea9f Mon Sep 17 00:00:00 2001
From: Miklos Szeredi <mszeredi@redhat.com>
Date: Tue, 22 Jun 2021 09:15:35 +0200
Subject: [PATCH] fuse: reject internal errno

commit 49221cf86d18bb66fe95d3338cb33bd4b9880ca5 upstream.

Don't allow userspace to report errors that could be kernel-internal.

Reported-by: Anatoly Trosinenko <anatoly.trosinenko@gmail.com>
Fixes: 334f485df85a ("[PATCH] FUSE - device functions")
Cc: <stable@vger.kernel.org> # v2.6.14
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 fs/fuse/dev.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c
index d665f9f20d3c..d21e41735805 100644
--- a/fs/fuse/dev.c
+++ b/fs/fuse/dev.c
@@ -1883,7 +1883,7 @@ static ssize_t fuse_dev_do_write(struct fuse_dev *fud,
 	}
 
 	err = -EINVAL;
-	if (oh.error <= -1000 || oh.error > 0)
+	if (oh.error <= -512 || oh.error > 0)
 		goto err_finish;
 
 	spin_lock(&fpq->lock);