From: Miklos Szeredi mszeredi@redhat.com

mainline inclusion from mainline-5.14 commit 76224355db7570cbe6b6f75c8929a1558828dd55 category: bugfix bugzilla: 181107 CVE: NA ---------------------------

fuse_finish_open() will be called with FUSE_NOWRITE in case of atomic O_TRUNC. This can deadlock with fuse_wait_on_page_writeback() in fuse_launder_page() triggered by invalidate_inode_pages2().

Fix by replacing invalidate_inode_pages2() in fuse_finish_open() with a truncate_pagecache() call. This makes sense regardless of FOPEN_KEEP_CACHE or fc->writeback cache, so do it unconditionally.

Reported-by: Xie Yongji xieyongji@bytedance.com Reported-and-tested-by: syzbot+bea44a5189836d956894@syzkaller.appspotmail.com Fixes: e4648309b85a ("fuse: truncate pending writes on O_TRUNC") Cc: stable@vger.kernel.org Signed-off-by: Miklos Szeredi mszeredi@redhat.com

Conflict: fs/fuse/file.c Signed-off-by: Yu Kuai yukuai3@huawei.com Reviewed-by: Zhang Yi yi.zhang@huawei.com Signed-off-by: Yang Yingliang yangyingliang@huawei.com --- fs/fuse/file.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/fs/fuse/file.c b/fs/fuse/file.c index 41e2a7b567d7f..5ecabacabd477 100644 --- a/fs/fuse/file.c +++ b/fs/fuse/file.c @@ -178,8 +178,6 @@ void fuse_finish_open(struct inode *inode, struct file *file)

if (ff->open_flags & FOPEN_DIRECT_IO) file->f_op = &fuse_direct_io_file_operations; - if (!(ff->open_flags & FOPEN_KEEP_CACHE)) - invalidate_inode_pages2(inode->i_mapping); if (ff->open_flags & FOPEN_STREAM) stream_open(inode, file); else if (ff->open_flags & FOPEN_NONSEEKABLE) @@ -191,10 +189,13 @@ void fuse_finish_open(struct inode *inode, struct file *file) fi->attr_version = ++fc->attr_version; i_size_write(inode, 0); spin_unlock(&fc->lock); + truncate_pagecache(inode, 0); fuse_invalidate_attr(inode); if (fc->writeback_cache) file_update_time(file); - } + } else if (!(ff->open_flags & FOPEN_KEEP_CACHE)) + invalidate_inode_pages2(inode->i_mapping); + if ((file->f_mode & FMODE_WRITE) && fc->writeback_cache) fuse_link_write_file(file); }