linux-kernel - AW: Resend [PATCH] kernel/resource.c: invalidate parent when freed resource has childs

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <421b9738bee141648d87a5b1c1b4d4aa@SVR-IES-MBX-03.mgc.mentorg.com>
Date:   Tue, 13 Aug 2019 08:09:29 +0000
From:   "Schmid, Carsten" <Carsten_Schmid@...tor.com>
To:     Linus Torvalds <torvalds@...ux-foundation.org>,
        Wei Yang <richard.weiyang@...il.com>
CC:     "bp@...e.de" <bp@...e.de>,
        "dan.j.williams@...el.com" <dan.j.williams@...el.com>,
        "mingo@...nel.org" <mingo@...nel.org>,
        "dave.hansen@...ux.intel.com" <dave.hansen@...ux.intel.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "bhelgaas@...gle.com" <bhelgaas@...gle.com>,
        "osalvador@...e.de" <osalvador@...e.de>,
        "rdunlap@...radead.org" <rdunlap@...radead.org>,
        "richardw.yang@...ux.intel.com" <richardw.yang@...ux.intel.com>,
        "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>
Subject: AW: Resend [PATCH] kernel/resource.c: invalidate parent when freed
 resource has childs

> >
> > In theory, child may have siblings. Would it be possible to have several
> > devices under xhci-hcd?
> 
> I'm less interested in the xhci-hcd case - which I certainly *hope* is
> fixed already? - than in "if this happens somewhere else".
> 
> So if we do want to remove the parent (which may be a good idea with a
> warning), and want to make sure that the children are really removed
> from the resource hierarchy, we should do somethiing like
> 
>   static bool detach_children(struct resource *res)
>   {
>         res = res->child;
>         if (!res)
>                 return false;
>         do {
>                 res->parent = NULL;
>                 res = res->sibling;
>         } while (res);
>         return true;
>   }
> 
> and then we could write the __release_region() warning as
> 
>         /* You should not release a resource that has children */
>         WARN_ON_ONCE(detach_children(res));
> 
> or something?
> 
... and a child may have children too ...

There is a __release_child_resources in resource.c around line 242.
A bit noisy, and does a similar thing you outlined above.
I'm thinking about to re-use that, but with more precise output
and WARN_ON_ONCE.

Suggestions before i start work on that?

Best regards
Carsten