[Dapper] [CVE-2010-4249] [PATCH 1/1] af_unix: limit unix_tot_inflight, CVE-2010-4249

[Tim Gardner]

On 04/23/2011 09:02 AM, Brad Figg wrote:
> On 04/23/2011 05:52 AM, Tim Gardner wrote:
>> On 04/22/2011 02:47 PM, Brad Figg wrote:
>>> From: Eric Dumazet<eric.dumazet at gmail.com>
>>>
>>> CVE-2010-4249
>>>
>>> BugLink: http://bugs.launchpad.net/bugs/769182
>>>
>>> Vegard Nossum found a unix socket OOM was possible, posting an exploit
>>> program.
>>>
>>> My analysis is we can eat all LOWMEM memory before unix_gc() being
>>> called from unix_release_sock(). Moreover, the thread blocked in
>>> unix_gc() can consume huge amount of time to perform cleanup because of
>>> huge working set.
>>>
>>> One way to handle this is to have a sensible limit on unix_tot_inflight,
>>> tested from wait_for_unix_gc() and to force a call to unix_gc() if this
>>> limit is hit.
>>>
>>> This solves the OOM and also reduce overall latencies, and should not
>>> slowdown normal workloads.
>>>
>>> Reported-by: Vegard Nossum<vegard.nossum at gmail.com>
>>> Signed-off-by: Eric Dumazet<eric.dumazet at gmail.com>
>>> Signed-off-by: David S. Miller<davem at davemloft.net>
>>> Signed-off-by: Brad Figg<brad.figg at canonical.com>
>>> ---
>>> net/unix/garbage.c | 7 +++++++
>>> 1 files changed, 7 insertions(+), 0 deletions(-)
>>>
>>> diff --git a/net/unix/garbage.c b/net/unix/garbage.c
>>> index 040f952..26d22aa 100644
>>> --- a/net/unix/garbage.c
>>> +++ b/net/unix/garbage.c
>>> @@ -168,9 +168,16 @@ static void maybe_unmark_and_push(struct sock *x)
>>>
>>>
>>> static int gc_in_progress = 0;
>>> +#define UNIX_INFLIGHT_TRIGGER_GC 16000
>>>
>>> void wait_for_unix_gc(void)
>>> {
>>> + /*
>>> + * If number of inflight sockets is insane,
>>> + * force a garbage collect right now.
>>> + */
>>> + if (atomic_read(&unix_tot_inflight)> UNIX_INFLIGHT_TRIGGER_GC&&
>>> !gc_in_progress)
>>> + unix_gc();
>>> wait_event(unix_gc_wait, gc_in_progress == 0);
>>> }
>>>
>>
>> Looks reasonable. Was this a clean cherry-pick, or a backport ?
>>
>> Acked-by: Tim Gardner <tim.gardner at canonical.com>
>>
>
> It's a clean cherry-pick.
>

I guess my point was that if the patch is a clean cherry-pick, then it 
ought to have the upstream SHA1 embedded in the commit log by using the 
'-x' option to 'git cherry-pick'. iF it is a backport, then note the 
upstream SHA1 from which the backport originated.

rtg
-- 
Tim Gardner tim.gardner at canonical.com