From 8aab336b14c115c6bf1d4baeb9247e41ed9ce6de Mon Sep 17 00:00:00 2001
From: Miklos Szeredi <mszeredi@redhat.com>
Date: Tue, 12 Nov 2019 11:49:04 +0100
Subject: fuse: verify write return

Make sure filesystem is not returning a bogus number of bytes written.

Fixes: ea9b9907b82a ("fuse: implement perform_write")
Cc: <stable@vger.kernel.org> # v2.6.26
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
---
 fs/fuse/file.c | 2 ++
 1 file changed, 2 insertions(+)

(limited to 'fs/fuse')

diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index db48a5cf8620..795d0f24d8b4 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -1096,6 +1096,8 @@ static ssize_t fuse_send_write_pages(struct fuse_io_args *ia,
 	ia->write.in.flags = fuse_write_flags(iocb);
 
 	err = fuse_simple_request(fc, &ap->args);
+	if (!err && ia->write.out.size > count)
+		err = -EIO;
 
 	offset = ap->descs[0].offset;
 	count = ia->write.out.size;
-- 
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