On Mon, 2007-11-19 at 12:51 +0000, Christoph Hellwig wrote: > On Fri, Nov 16, 2007 at 06:06:51PM +0300, Alexey Dobriyan wrote: > > proc_kill_inodes() can clear ->i_fop in the middle of vfs_readdir resulting > > in > > NULL dereference during "file->f_op->readdir(file, buf, filler)". > > > > The solution is to remove proc_kill_inodes() completely: > > a) we don't have tricky modules implementing their tricky readdir hooks > > which > > could keeping this revoke from hell. > > b) In a situation when module is gone but PDE still alive, standard readdir > > will return only "." and "..", because pde->next was cleared by > > remove_proc_entry(). > > c) the race proc_kill_inode() destined to prevent is not completely fixed, > > just > > race window made smaller, because vfs_readdir() is run without sb_lock > > held and > > without file_list_lock held. Effectively, ->i_fop is cleared at random > > moment, > > which can't fix properly anything. > > Nice, getting rid of this is a very good step formwards. Unfortunately > we have another copy of this junk in > security/selinux/selinuxfs.c:sel_remove_entries() which would need the > same treatment.
Can't just be dropped completely for selinux - we need a way to drop obsolete entries from the prior policy when we load a new policy. Is the only real problem here the clearing of f_op? If so, we can likely remove that from sel_remove_entries() without harm, and fix the checks for it to use something more reliable. -- Stephen Smalley National Security Agency - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
