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

[Brad Figg]

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.

-- 
Brad Figg brad.figg at canonical.com http://www.canonical.com