Hi Adrian,

On 10/31/15 16:01, Alexander V. Chernikov wrote:

31.10.2015, 16:46, "Adrian Chadd" <adr...@freebsd.org>:
On 31 October 2015 at 09:34, Alexander V. Chernikov
<melif...@freebsd.org> wrote:
  31.10.2015, 05:32, "Adrian Chadd" <adr...@freebsd.org>:

  Here's a panic from arptimer:
  Hi Adrian,

  As far as I see, line 205 in if_ether.c is IF_AFDATA_LOCK(ifp) which happens 
after LLE_WUNLOCK().
  So, it looks like (pre-cached) ifp had been freed before locking ifdata.
  Do you have any more details on that? (e.g. was some interface detached at 
that moment, is it reproducible, etc..)

  From a quick glance, potential use-after-free has been possible for quite a 
long time, but I wonder why it hasn't been observed before.
  Probably lltable_free() changes might have triggered that.

  I'll take a deeper look on that and reply.

Observed on an idle box with projects/hps_head too:

panic: bogus refcnt 0 on lle 0xfffff8016508ca00
cpuid = 7
KDB: stack backtrace:
db_trace_self_wrapper() at db_trace_self_wrapper+0x2b/frame 0xfffffe03e4e8c7e0
vpanic() at vpanic+0x182/frame 0xfffffe03e4e8c860
kassert_panic() at kassert_panic+0x126/frame 0xfffffe03e4e8c8d0
llentry_free() at llentry_free+0x136/frame 0xfffffe03e4e8c900
arptimer() at arptimer+0x20e/frame 0xfffffe03e4e8c950
softclock_call_cc() at softclock_call_cc+0x170/frame 0xfffffe03e4e8c9c0
softclock() at softclock+0x47/frame 0xfffffe03e4e8c9e0
intr_event_execute_handlers() at intr_event_execute_handlers+0x96/frame 
ithread_loop() at ithread_loop+0xa6/frame 0xfffffe03e4e8ca70
fork_exit() at fork_exit+0x84/frame 0xfffffe03e4e8cab0
fork_trampoline() at fork_trampoline+0xe/frame 0xfffffe03e4e8cab0
--- trap 0, rip = 0, rsp = 0, rbp = 0 ---

Looks like callout_reset() must be examined too, and was missed by:


Can you try the attached patch?

Randall: Can you fix this ASAP?

diff --git a/sys/dev/oce/oce_if.c b/sys/dev/oce/oce_if.c
index 826cd3c..1cca876 100644
--- a/sys/dev/oce/oce_if.c
+++ b/sys/dev/oce/oce_if.c
@@ -343,7 +343,7 @@ oce_attach(device_t dev)
 	callout_init(&sc->timer, 1);
 	rc = callout_reset(&sc->timer, 2 * hz, oce_local_timer, sc);
-	if (rc)
+	if (rc > 0)
 		goto stats_free;
 	return 0;
diff --git a/sys/netinet/if_ether.c b/sys/netinet/if_ether.c
index dfba0b2..0aec1c4 100644
--- a/sys/netinet/if_ether.c
+++ b/sys/netinet/if_ether.c
@@ -420,7 +420,7 @@ arpresolve_full(struct ifnet *ifp, int is_gw, int create, struct mbuf *m,
 		la->la_expire = time_uptime;
 		canceled = callout_reset(&la->lle_timer, hz * V_arpt_down,
 		    arptimer, la);
-		if (canceled)
+		if (canceled > 0)
@@ -1084,7 +1084,7 @@ arp_mark_lle_reachable(struct llentry *la)
 		la->la_expire = time_uptime + V_arpt_keep;
 		canceled = callout_reset(&la->lle_timer,
 		    hz * V_arpt_keep, arptimer, la);
-		if (canceled)
+		if (canceled > 0)
 	la->la_asked = 0;
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