Re: use-after-free in sctp_do_sm

[Dmitry Vyukov <dvyukov@google.com>]

On Fri, Dec 4, 2015 at 10:34 PM, Marcelo Ricardo Leitner
<marcelo.leitner@gmail.com> wrote:
> On Fri, Dec 04, 2015 at 09:25:35PM +0100, Dmitry Vyukov wrote:
>> On Fri, Dec 4, 2015 at 6:48 PM, Marcelo Ricardo Leitner
>> <marcelo.leitner@gmail.com> wrote:
>> > Hi Dmitry,
>> >
>> > Can you please test this patch?
>> > I'll re-post with proper subject if it works.
>>
>> Still happening with the same stacks.
>
> Then there may be another one, I'm afraid.
>
> I'm using the testapp you shared in the first email, with that debug line
> enabled and added a new one:
> +       pr_debug("%p %d\n", asoc, asoc ? asoc->state : 0);
>         debug_post_sfx();
> (should have used %x, but ok)
>
> Also enabled slub_debug=PUZ, and I get:
>
> without the patch:
> [   87.873640] sctp: ffff8800b71533d8 1
> [   87.873647] sctp: sctp_do_sm[post-sfx]: error:0,
> asoc:ffff8800b71533d8[STATE_CLOSED]
> [   87.873739] sctp: ffff8800b71533d8 1
> [   87.873742] sctp: sctp_do_sm[post-sfx]: error:0,
> asoc:ffff8800b71533d8[STATE_CLOSED]
> [   87.875149] sctp: ffff8800b71533d8 1802201963
> [   87.875238] sctp: sctp_do_sm[post-sfx]: error:0,
> asoc:ffff8800b71533d8[STATE_CLOSED]
>
> 1802201963 = 0x6b6b6b6b, poison
>
> with the patch:
> [   81.071265] sctp: ffff880137571148 1
> [   81.071273] sctp: sctp_do_sm[post-sfx]: error:0,
> asoc:ffff880137571148[STATE_CLOSED]
> [   81.071372] sctp: ffff880137571148 1
> [   81.071375] sctp: sctp_do_sm[post-sfx]: error:0,
> asoc:ffff880137571148[STATE_CLOSED]
> [   81.072423] sctp:           (null) 0
> [   81.072427] sctp: sctp_do_sm[post-sfx]: error:0, asoc:
> (null)[STATE_CLOSED]
>
> This one, at least, is gone with this patch.


I will try to extract reproducer next week.