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Fix race conditions involved in setting IP multicast options. This should

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fix Dennis Fortin's problem for good, if I've got it figured out right.

(The problem was that a `struct ifaddr' could get deleted out from under
the current requester, thus leaving him with an invalid interface pointer
and causing even more bogus accesses.)
This commit is contained in:
Garrett Wollman 1995-03-20 18:11:31 +00:00
parent 1a96efa2b8
commit 9b626c29f7
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=7190
1 changed files with 17 additions and 1 deletions
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18
sys/netinet/ip_output.c
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@ -31,7 +31,7 @@
* SUCH DAMAGE.
*
* @(#)ip_output.c 8.3 (Berkeley) 1/21/94
* $Id: ip_output.c,v 1.12 1995/01/12 13:06:31 ugen Exp $
* $Id: ip_output.c,v 1.13 1995/03/16 18:14:59 bde Exp $
*/
#include <sys/param.h>
@ -790,6 +790,7 @@ ip_setmoptions(optname, imop, m)
register struct ip_moptions *imo = *imop;
struct route ro;
register struct sockaddr_in *dst;
int s;
if (imo == NULL) {
/*
@ -851,12 +852,14 @@ ip_setmoptions(optname, imop, m)
* IP address. Find the interface and confirm that
* it supports multicasting.
*/
s = splnet();
INADDR_TO_IFP(addr, ifp);
if (ifp == NULL || (ifp->if_flags & IFF_MULTICAST) == 0) {
error = EADDRNOTAVAIL;
break;
}
imo->imo_multicast_ifp = ifp;
splx(s);
break;
case IP_MULTICAST_TTL:
@ -897,6 +900,7 @@ ip_setmoptions(optname, imop, m)
error = EINVAL;
break;
}
s = splnet();
/*
* If no interface address was provided, use the interface of
* the route to the given multicast address.
@ -910,6 +914,7 @@ ip_setmoptions(optname, imop, m)
rtalloc(&ro);
if (ro.ro_rt == NULL) {
error = EADDRNOTAVAIL;
splx(s);
break;
}
ifp = ro.ro_rt->rt_ifp;
@ -918,12 +923,14 @@ ip_setmoptions(optname, imop, m)
else {
INADDR_TO_IFP(mreq->imr_interface, ifp);
}
/*
* See if we found an interface, and confirm that it
* supports multicast.
*/
if (ifp == NULL || (ifp->if_flags & IFF_MULTICAST) == 0) {
error = EADDRNOTAVAIL;
splx(s);
break;
}
/*
@ -938,10 +945,12 @@ ip_setmoptions(optname, imop, m)
}
if (i < imo->imo_num_memberships) {
error = EADDRINUSE;
splx(s);
break;
}
if (i == IP_MAX_MEMBERSHIPS) {
error = ETOOMANYREFS;
splx(s);
break;
}
/*
@ -951,9 +960,11 @@ ip_setmoptions(optname, imop, m)
if ((imo->imo_membership[i] =
in_addmulti(&mreq->imr_multiaddr, ifp)) == NULL) {
error = ENOBUFS;
splx(s);
break;
}
++imo->imo_num_memberships;
splx(s);
break;
case IP_DROP_MEMBERSHIP:
@ -970,6 +981,8 @@ ip_setmoptions(optname, imop, m)
error = EINVAL;
break;
}
s = splnet();
/*
* If an interface address was specified, get a pointer
* to its ifnet structure.
@ -980,6 +993,7 @@ ip_setmoptions(optname, imop, m)
INADDR_TO_IFP(mreq->imr_interface, ifp);
if (ifp == NULL) {
error = EADDRNOTAVAIL;
splx(s);
break;
}
}
@ -995,6 +1009,7 @@ ip_setmoptions(optname, imop, m)
}
if (i == imo->imo_num_memberships) {
error = EADDRNOTAVAIL;
splx(s);
break;
}
/*
@ -1008,6 +1023,7 @@ ip_setmoptions(optname, imop, m)
for (++i; i < imo->imo_num_memberships; ++i)
imo->imo_membership[i-1] = imo->imo_membership[i];
--imo->imo_num_memberships;
splx(s);
break;
default: