| Message ID | 20220629112647.4141034-2-yi.zhang@huawei.com |
|---|---|
| State | Accepted, archived |
| Headers | show |
| Series | [v3,1/2] ext4: silence the warning when evicting inode with dioread_nolock | expand |
On Wed 29-06-22 19:26:47, Zhang Yi wrote: > 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> > --- > v2->v3: > - Switch to use WARN_ON_ONCE instead of ASSERT. Thanks! Feel free to add: Reviewed-by: Jan Kara <jack@suse.cz> Honza > > fs/ext4/inode.c | 6 ++++++ > 1 file changed, 6 insertions(+) > > diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c > index 702cc208689a..902393373152 100644 > --- a/fs/ext4/inode.c > +++ b/fs/ext4/inode.c > @@ -333,6 +333,12 @@ 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... */ > -- > 2.31.1 >
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index 702cc208689a..902393373152 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -333,6 +333,12 @@ 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... */
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> --- v2->v3: - Switch to use WARN_ON_ONCE instead of ASSERT. fs/ext4/inode.c | 6 ++++++ 1 file changed, 6 insertions(+)