From: Zhang Yi yi.zhang@huawei.com
commit 318cdc822c63b6e2befcfdc2088378ae6fa18def upstream.
In ext4_evict_inode(), if we evicting an inode in the 'no_delete' path, it cannot be raced by another mark_inode_dirty(). If it happens, someone else may accidentally dirty it without holding inode refcount and probably cause use-after-free issues in the writeback procedure. It's indiscoverable and hard to debug, so add an WARN_ON_ONCE() to check and detect this issue in advance.
Suggested-by: Jan Kara jack@suse.cz Signed-off-by: Zhang Yi yi.zhang@huawei.com Reviewed-by: Jan Kara jack@suse.cz Link: https://lore.kernel.org/r/20220629112647.4141034-2-yi.zhang@huawei.com Signed-off-by: Theodore Ts'o tytso@mit.edu Cc: stable@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/ext4/inode.c | 6 ++++++ 1 file changed, 6 insertions(+)
--- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -335,6 +335,12 @@ stop_handle: ext4_xattr_inode_array_free(ea_inode_array); return; no_delete: + /* + * Check out some where else accidentally dirty the evicting inode, + * which may probably cause inode use-after-free issues later. + */ + WARN_ON_ONCE(!list_empty_careful(&inode->i_io_list)); + if (!list_empty(&EXT4_I(inode)->i_fc_list)) ext4_fc_mark_ineligible(inode->i_sb, EXT4_FC_REASON_NOMEM, NULL); ext4_clear_inode(inode); /* We must guarantee clearing of inode... */