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MFC 198301

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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
Approved by:	re
Verified by:	rnoland, yongari
This commit is contained in:
Qing Li 2009-10-20 21:36:56 +00:00
parent 8ed4544ca7
commit 0eb4d28bac
1 changed files with 10 additions and 10 deletions
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20
sys/netinet/if_ether.c
View file

@ -168,17 +168,17 @@ arptimer(void *arg)
ifp = lle->lle_tbl->llt_ifp;
IF_AFDATA_LOCK(ifp);
LLE_WLOCK(lle);
if (((lle->la_flags & LLE_DELETED)
|| (time_second >= lle->la_expire))
&& (!callout_pending(&lle->la_timer) &&
callout_active(&lle->la_timer)))
if ((!callout_pending(&lle->la_timer) &&
callout_active(&lle->la_timer))) {
(void) llentry_free(lle);
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);
}
@ -365,7 +365,7 @@ 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);