From: Miklos Szeredi mszeredi@redhat.com
commit 035ff33cf4db101250fb980a3941bf078f37a544 upstream.
A race between write(2) and close(2) allows pages to be dirtied after fuse_flush -> write_inode_now(). If these pages are not flushed from fuse_release(), then there might not be a writable open file later. So any remaining dirty pages must be written back before the file is released.
This is a partial revert of the blamed commit.
Reported-by: syzbot+6e1efbd8efaaa6860e91@syzkaller.appspotmail.com Fixes: 36ea23374d1f ("fuse: write inode in fuse_vma_close() instead of fuse_release()") Cc: stable@vger.kernel.org # v5.16 Signed-off-by: Miklos Szeredi mszeredi@redhat.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/fuse/file.c | 9 +++++++++ 1 file changed, 9 insertions(+)
--- a/fs/fuse/file.c +++ b/fs/fuse/file.c @@ -338,6 +338,15 @@ static int fuse_open(struct inode *inode
static int fuse_release(struct inode *inode, struct file *file) { + struct fuse_conn *fc = get_fuse_conn(inode); + + /* + * Dirty pages might remain despite write_inode_now() call from + * fuse_flush() due to writes racing with the close. + */ + if (fc->writeback_cache) + write_inode_now(inode, 1); + fuse_release_common(file, false);
/* return value is ignored by VFS */