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fuse: write inode in fuse_release()

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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>
This commit is contained in:
Miklos Szeredi 2022-04-20 16:05:41 +02:00 committed by Greg Kroah-Hartman
parent ed2ac89f29
commit 4bd9d5d20f
1 changed files with 9 additions and 0 deletions
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9
fs/fuse/file.c
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@ -338,6 +338,15 @@ static int fuse_open(struct inode *inode, struct file *file)
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 */