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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