The patch below does not apply to the 4.19-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

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: [PATCH] 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

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;