Hi,
On 10/6/16 1:10 PM, Slawa Olhovchenkov wrote:> On Thu, Oct 06, 2016 at 09:28:06AM +0200, Julien Charbon wrote:
>
>> 2. thread1: In tcp_close() the inp is marked with INP_DROPPED flag,
the
>> process continues and calls INP_WUNLOCK() here:
>>
>>
https://github.com/freebsd/freebsd/blob/releng/11.0/sys/netinet/tcp_subr.c#L1568
>
> Look also to sys/netinet/tcp_timewait.c:488
>
> And check other locks from r160549
You are right, and here the a fix proposal for this issue:
Fix a double-free when an inp transitions to INP_TIMEWAIT state after
having been dropped
https://reviews.freebsd.org/D8211
It basically enforces in_pcbdrop() logic in tcp_input(): A INP_DROPPED
inpcb should never be proceed further.
Slawa, as you are the only one to reproduce this issue currently, could
test this patch? (And remove the temporary patch I did provided to you
before).
I will wait for your tests results before pushing further.
Thanks!
diff --git a/sys/netinet/tcp_input.c b/sys/netinet/tcp_input.c
index c72f01f..37f27e0 100644
--- a/sys/netinet/tcp_input.c
+++ b/sys/netinet/tcp_input.c
@@ -921,6 +921,16 @@ findpcb:
goto dropwithreset;
}
INP_WLOCK_ASSERT(inp);
+ /*
+ * While waiting for inp lock during the lookup, another thread
+ * can have droppedt the inpcb, in which case we need to loop back
+ * and try to find a new inpcb to deliver to.
+ */
+ if (inp->inp_flags & INP_DROPPED) {
+ INP_WUNLOCK(inp);
+ inp = NULL;
+ goto findpcb;
+ }
if ((inp->inp_flowtype == M_HASHTYPE_NONE) &&
(M_HASHTYPE_GET(m) != M_HASHTYPE_NONE) &&
((inp->inp_socket == NULL) ||
@@ -981,6 +991,10 @@ relocked:
if (in_pcbrele_wlocked(inp)) {
inp = NULL;
goto findpcb;
+ } else if (inp->inp_flags & INP_DROPPED)
{
+ INP_WUNLOCK(inp);
+ inp = NULL;
+ goto findpcb;
}
} else
ti_locked = TI_RLOCKED;
@@ -1040,6 +1054,10 @@ relocked:
if (in_pcbrele_wlocked(inp)) {
inp = NULL;
goto findpcb;
+ } else if (inp->inp_flags & INP_DROPPED)
{
+ INP_WUNLOCK(inp);
+ inp = NULL;
+ goto findpcb;
}
goto relocked;
} else
--
Julien
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