Author: qingli
Date: Tue Oct 20 17:55:42 2009
New Revision: 198301
URL: http://svn.freebsd.org/changeset/base/198301
Log:
In the ARP callout timer expiration function, the current time_second
is compared against the entry expiration time value (that was set based
on time_second) to check if the current time is larger than the set
expiration time. Due to the +/- timer granularity value, the comparison
returns false, causing the alternative code to be executed. The
alternative code path freed the memory without removing that entry
from the table list, causing a use-after-free bug.
Reviewed by: discussed with kmacy
MFC after: immediately
Verified by: rnoland, yongari
Modified:
head/sys/netinet/if_ether.c
Modified: head/sys/netinet/if_ether.c
==============================================================================
--- head/sys/netinet/if_ether.c Tue Oct 20 17:50:36 2009 (r198300)
+++ head/sys/netinet/if_ether.c Tue Oct 20 17:55:42 2009 (r198301)
@@ -175,18 +175,18 @@ arptimer(void *arg)
CURVNET_SET(ifp->if_vnet);
IF_AFDATA_LOCK(ifp);
LLE_WLOCK(lle);
- if (((lle->la_flags & LLE_DELETED) ||
- (time_second >= lle->la_expire)) &&
- (!callout_pending(&lle->la_timer) &&
+ if ((!callout_pending(&lle->la_timer) &&
callout_active(&lle->la_timer))) {
(void) llentry_free(lle);
ARPSTAT_INC(timeouts);
- } else {
- /*
- * Still valid, just drop our reference
- */
- LLE_FREE_LOCKED(lle);
+ }
+#ifdef DIAGNOSTICS
+ else {
+ struct sockaddr *l3addr = L3_ADDR(lle);
+ log(LOG_INFO, "arptimer issue: %p, IPv4 address: \"%s\"\n", lle,
+ inet_ntoa(((const struct sockaddr_in *)l3addr)->sin_addr));
}
+#endif
IF_AFDATA_UNLOCK(ifp);
CURVNET_RESTORE();
}
@@ -377,7 +377,7 @@ retry:
if (renew) {
LLE_ADDREF(la);
- la->la_expire = time_second;
+ la->la_expire = time_second + V_arpt_down;
callout_reset(&la->la_timer, hz * V_arpt_down, arptimer, la);
la->la_asked++;
LLE_WUNLOCK(la);
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