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fs: do not update freeing inode i_io_list

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[ Upstream commit 4e3c51f4e8 ]

After commit cbfecb927f ("fs: record I_DIRTY_TIME even if inode
already has I_DIRTY_INODE") writeback_single_inode can push inode with
I_DIRTY_TIME set to b_dirty_time list. In case of freeing inode with
I_DIRTY_TIME set this can happen after deletion of inode from i_io_list
at evict. Stack trace is following.

evict
fat_evict_inode
fat_truncate_blocks
fat_flush_inodes
writeback_inode
sync_inode_metadata(inode, sync=0)
writeback_single_inode(inode, wbc) <- wbc->sync_mode == WB_SYNC_NONE

This will lead to use after free in flusher thread.

Similar issue can be triggered if writeback_single_inode in the
stack trace update inode->i_io_list. Add explicit check to avoid it.

Fixes: cbfecb927f ("fs: record I_DIRTY_TIME even if inode already has I_DIRTY_INODE")
Reported-by: syzbot+6ba92bd00d5093f7e371@syzkaller.appspotmail.com
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Svyatoslav Feldsherov <feldsherov@google.com>
Link: https://lore.kernel.org/r/20221115202001.324188-1-feldsherov@google.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Svyatoslav Feldsherov 2022-11-15 20:20:01 +00:00 committed by Greg Kroah-Hartman
parent 8db9e60cdf
commit 8ce9b1c97f
1 changed files with 19 additions and 11 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

30
fs/fs-writeback.c
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@ -1739,18 +1739,26 @@ static int writeback_single_inode(struct inode *inode,
wb = inode_to_wb_and_lock_list(inode);
spin_lock(&inode->i_lock);
/*
* If the inode is now fully clean, then it can be safely removed from
* its writeback list (if any). Otherwise the flusher threads are
* responsible for the writeback lists.
* If the inode is freeing, its i_io_list shoudn't be updated
* as it can be finally deleted at this moment.
*/
if (!(inode->i_state & I_DIRTY_ALL))
inode_cgwb_move_to_attached(inode, wb);
else if (!(inode->i_state & I_SYNC_QUEUED)) {
if ((inode->i_state & I_DIRTY))
redirty_tail_locked(inode, wb);
else if (inode->i_state & I_DIRTY_TIME) {
inode->dirtied_when = jiffies;
inode_io_list_move_locked(inode, wb, &wb->b_dirty_time);
if (!(inode->i_state & I_FREEING)) {
/*
* If the inode is now fully clean, then it can be safely
* removed from its writeback list (if any). Otherwise the
* flusher threads are responsible for the writeback lists.
*/
if (!(inode->i_state & I_DIRTY_ALL))
inode_cgwb_move_to_attached(inode, wb);
else if (!(inode->i_state & I_SYNC_QUEUED)) {
if ((inode->i_state & I_DIRTY))
redirty_tail_locked(inode, wb);
else if (inode->i_state & I_DIRTY_TIME) {
inode->dirtied_when = jiffies;
inode_io_list_move_locked(inode,
wb,
&wb->b_dirty_time);
}
}
}