maldiohead/cve-2019-6207fuite d'informations du tas du noyau xnu
cette vulnérabilité peut être déclenchée en sandbox sur macOS< 10.14.5 &&ios < 12.2
Je mettrai à jour plus de détails sur cette vulnérabilité.
Il y a un bug dans sysctl_dumpentry, qui peut fuiter des informations du heap.
Détails:
1.Comme la description de la fonction, sysctl_dumpentry est utilisé pour dumper la table du noyau via sysctl(), cette fonction va malloc un buffer au niveau de rt_msg2, puis rt_msg2 utilise _MALLOC (sans le flag M_ZERO) pour allouer la mémoire, ensuite le buffer sera utilisé comme objet rt_msghdr2.
Cependant, lors de l'initialisation de l'objet rt_msghdr2 (voir ci-dessous), il laisse un trou, ce qui signifie que la variable rtm_inits n'est pas initialisée.
La fonction utilisera SYSCTL_OUT pour copier les données vers userspace, ce qui conduit au bug de fuite d'informations du heap du noyau.
static int sysctl_dumpentry(struct radix_node *rn, void *vw)
{
struct walkarg *w = vw;
struct rtentry *rt = (struct rtentry *)rn;
int error = 0, size;
struct rt_addrinfo info;
kauth_cred_t cred;
kauth_cred_t *credp;
cred = kauth_cred_proc_ref(current_proc());
credp = &cred;
RT_LOCK(rt);
if ((w->w_op == NET_RT_FLAGS || w->w_op == NET_RT_FLAGS_PRIV) &&
!(rt->rt_flags & w->w_arg))
goto done;
/*
* If the matching route has RTF_LLINFO set, then we can skip scrubbing the MAC
* only if the outgoing interface is not loopback and the process has entitlement
* for neighbor cache read.
*/
if (w->w_op == NET_RT_FLAGS_PRIV && (rt->rt_flags & RTF_LLINFO)) {
if (rt->rt_ifp != lo_ifp &&
(route_op_entitlement_check(NULL, cred, ROUTE_OP_READ, TRUE) == 0)) {
credp = NULL;
}
}
bzero((caddr_t)&info, sizeof (info));
info.rti_info[RTAX_DST] = rt_key(rt);
info.rti_info[RTAX_GATEWAY] = rt->rt_gateway;
info.rti_info[RTAX_NETMASK] = rt_mask(rt);
info.rti_info[RTAX_GENMASK] = rt->rt_genmask;
if (w->w_op != NET_RT_DUMP2) {
size = rt_msg2(RTM_GET, &info, NULL, w, credp); //alloc memory without initial
if (w->w_req != NULL && w->w_tmem != NULL) {
struct rt_msghdr *rtm =
(struct rt_msghdr *)(void *)w->w_tmem;
rtm->rtm_flags = rt->rt_flags;
rtm->rtm_use = rt->rt_use;
rt_getmetrics(rt, &rtm->rtm_rmx);
rtm->rtm_index = rt->rt_ifp->if_index;
rtm->rtm_pid = 0;
rtm->rtm_seq = 0;
rtm->rtm_errno = 0;
rtm->rtm_addrs = info.rti_addrs;
error = SYSCTL_OUT(w->w_req, (caddr_t)rtm, size); // copyout
}
} else {
size = rt_msg2(RTM_GET2, &info, NULL, w, credp); // alloc memory without initial
if (w->w_req != NULL && w->w_tmem != NULL) {
struct rt_msghdr2 *rtm =
(struct rt_msghdr2 *)(void *)w->w_tmem;
rtm->rtm_flags = rt->rt_flags;
rtm->rtm_use = rt->rt_use;
rt_getmetrics(rt, &rtm->rtm_rmx);
rtm->rtm_index = rt->rt_ifp->if_index;
rtm->rtm_refcnt = rt->rt_refcnt;
if (rt->rt_parent)
rtm->rtm_parentflags = rt->rt_parent->rt_flags;
else
rtm->rtm_parentflags = 0;
rtm->rtm_reserved = 0;
rtm->rtm_addrs = info.rti_addrs;
error = SYSCTL_OUT(w->w_req, (caddr_t)rtm, size); // copyout
}
}
done:
RT_UNLOCK(rt);
kauth_cred_unref(&cred);
return (error);
}