Commit 318cdc82 authored by Zhang Yi's avatar Zhang Yi Committed by Theodore Ts'o
Browse files

ext4: check and assert if marking an no_delete evicting inode dirty 



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: default avatarJan Kara <jack@suse.cz>
Signed-off-by: default avatarZhang Yi <yi.zhang@huawei.com>
Reviewed-by: default avatarJan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20220629112647.4141034-2-yi.zhang@huawei.com


Signed-off-by: default avatarTheodore Ts'o <tytso@mit.edu>
Cc: stable@kernel.org
parent bc12ac98

fs/ext4/inode.c

+6 −0
Original line number Diff line number Diff line
@@ -335,6 +335,12 @@ void ext4_evict_inode(struct inode *inode) 
	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... */