Messages in this thread | | | Date | Wed, 6 May 2020 15:49:52 -0700 | From | Kees Cook <> | Subject | Re: [PATCH] securityfs: Add missing d_delete() call on removal |
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On Wed, May 06, 2020 at 07:49:20PM +0100, Al Viro wrote: > On Wed, May 06, 2020 at 08:34:29AM -0700, Kees Cook wrote: > > > Just posted the whole series: > > https://lore.kernel.org/lkml/20200506152114.50375-1-keescook@chromium.org/ > > > > But the specific question was driven by this patch: > > https://lore.kernel.org/lkml/20200506152114.50375-11-keescook@chromium.org/ > > Yecchh... First of all, you are leaving a dangling pointer in your > struct pstore_private ->dentry. What's more, in your case d_delete()
Yeah, good idea: I can wipe out the pstore_private->dentry at this point just for robustness. From what I could tell the evict got immediately called after the dput().
> is definitely wrong - either there are other references to dentry > (in which case d_delete() is the same as d_drop()), or dput() right > after it will drive ->d_count to zero and since you end up using > simple_dentry_operations, dentry will be freed immediately after > that.
Do you mean the d_drop() isn't needed? What happens if someone has the file open during this routine? The goal here is to make these files disappear so they'll go through evict.
> I have not looked at the locking in that series yet, so no comments
Yeah, I would not be surprised by some more locking issues, but I think it's an improvement over what was there. Most of the code seems to have been designed to be non-modular. :P
> on the races, but in any case - that d_delete() is a misspelled d_drop().
I'll change it; thanks!
-- Kees Cook
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