7e7f29200f
commit 7df1e988c723a066754090b22d047c3225342152 upstream.
Buffered read in fuse normally goes via:
-> generic_file_buffered_read()
-> fuse_readpages()
-> fuse_send_readpages()
->fuse_simple_request() [called since v5.4]
In the case of a read request, fuse_simple_request() will return a
non-negative bytecount on success or a negative error value. A positive
bytecount was taken to be an error and the PG_error flag set on the page.
This resulted in generic_file_buffered_read() falling back to ->readpage(),
which would repeat the read request and succeed. Because of the repeated
read succeeding the bug was not detected with regression tests or other use
cases.
The FTP module in GVFS however fails the second read due to the
non-seekable nature of FTP downloads.
Fix by checking and ignoring positive return value from
fuse_simple_request().
Reported-by: Ondrej Holy <oholy@redhat.com>
Link: https://gitlab.gnome.org/GNOME/gvfs/issues/441
Fixes: 134831e36bbd ("fuse: convert readpages to simple api")
Cc: <stable@vger.kernel.org> # v5.4
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.