Re: [PATCH] Destroy ACLs in the reverse order of creation

On 29/11/2013 1:33 p.m., Alex Rousskov wrote:
> Hello,
>
> The attached patch destroys ACLs in the reverse order of creation to
> avoid destruction segfaults during reconfiguration. I could reproduce
> segfaults in v3.3-based code. I saw access to the already destroyed ACL
> memory in trunk; I suspect trunk did not segfault by luck as the bug
> appears to be there.
>
> Group ACLs created later may use other ACLs created earlier. A group ACL
> must be deleted first so that its AclDeleter can safely access
> registration status (and avoid double deletion) of the ACLs it uses.
> Since ACLs are remembered (in Config.aclList) using a singly-linked
> list, it is difficult to change their deletion order. Instead, we
> changed their listing order from FIFO to LIFO.
>
> As far as I can tell, the ACL storage order is not important for the
> rest of the code but please let me know if I missed any cases.
>
>
> Thank you,
>
> Alex.
>

I think we really should be ref-counting these pointers to make it a bit
more flexible and ensure that they do not get erased while in use.

+0. I have no objections for this going in now while we consider the above.

Amos
Received on Sat Nov 30 2013 - 12:35:32 MST