93a5de7e88
[ Upstream commit 9fa248c65bdbf5af0a2f74dd38575acfc8dfd2bf ]
There's a race in fuse's readdir cache that can result in an uninitilized
page being read. The page lock is supposed to prevent this from happening
but in the following case it doesn't:
Two fuse_add_dirent_to_cache() start out and get the same parameters
(size=0,offset=0). One of them wins the race to create and lock the page,
after which it fills in data, sets rdc.size and unlocks the page.
In the meantime the page gets evicted from the cache before the other
instance gets to run. That one also creates the page, but finds the
size to be mismatched, bails out and leaves the uninitialized page in the
cache.
Fix by marking a filled page uptodate and ignoring non-uptodate pages.
Reported-by: Frank Sorenson <fsorenso@redhat.com>
Fixes: 5d7bc7e8680c ("fuse: allow using readdir cache")
Cc: <stable@vger.kernel.org> # v4.20
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.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.