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address: fix use after free #342

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Merged
maxime-leroy merged 1 commit into from
Oct 13, 2025
Merged

address: fix use after free #342

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16 changes: 15 additions & 1 deletion modules/ip/control/address.c
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Original file line number Diff line number Diff line change
Expand Up @@ -10,6 +10,7 @@
#include <gr_module.h>
#include <gr_net_types.h>
#include <gr_queue.h>
#include <gr_rcu.h>
#include <gr_vec.h>

#include <event2/event.h>
Expand Down Expand Up @@ -108,7 +109,20 @@ static struct api_out addr_add(const void *request, struct api_ctx *) {
if (ret < 0)
return api_out(-ret, 0, NULL);

gr_vec_add(ifaddrs->nh, nh);
// gr_vec_add may realloc() and free the old vector
// Duplicate the whole vector and append to the clone.
gr_vec struct nexthop **nhs_copy = NULL;
gr_vec struct nexthop **nhs_old = ifaddrs->nh;
gr_vec_cap_set(nhs_copy, gr_vec_len(nhs_old) + 1); // avoid malloc+realloc
gr_vec_extend(nhs_copy, nhs_old);
gr_vec_add(nhs_copy, nh);
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@maxime-leroy maxime-leroy Oct 12, 2025

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gr_vec_clone will to do a malloc, gr_vec_add will do a realloc, it could be optimized:
gr_vec_grow(nhs_copy, gr_vec_len(nhs_old) +1) ;
gr_vec_extend(nhs_copy, nh_old);
gr_vec_add(nhs_copy, nh);

no ?

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@rjarry rjarry Oct 13, 2025

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I could change this to:

        gr_vec struct nexthop **nhs_copy = NULL;
        gr_vec struct nexthop **nhs_old = ifaddrs->nh;
        gr_vec_cap_set(nhs_copy, gr_vec_len(nhs_old) + 1);
        gr_vec_extend(nhs_copy, ifaddrs->nh);
        gr_vec_add(nhs_copy, nh);
        ifaddrs->nh = nhs_copy;

But it is less readable.

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@rjarry rjarry Oct 13, 2025

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I don't really mind. Let me know what you prefer.

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@maxime-leroy maxime-leroy Oct 13, 2025

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I prefer this one, it is still readable, more efficient

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@rjarry rjarry Oct 13, 2025

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done

ifaddrs->nh = nhs_copy;
if (nhs_old != NULL) {
// Once all datapath workers have seen the new clone, free the old one.
rte_rcu_qsbr_synchronize(gr_datapath_rcu(), RTE_QSBR_THRID_INVALID);
gr_vec_free(nhs_old);
}

gr_event_push(GR_EVENT_IP_ADDR_ADD, &req->addr);

return api_out(0, 0, NULL);
Expand Down
31 changes: 29 additions & 2 deletions modules/ip6/control/address.c
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Original file line number Diff line number Diff line change
Expand Up @@ -10,6 +10,7 @@
#include <gr_module.h>
#include <gr_net_types.h>
#include <gr_queue.h>
#include <gr_rcu.h>
#include <gr_vec.h>

#include <event2/event.h>
Expand Down Expand Up @@ -138,7 +139,20 @@ static int mcast6_addr_add(const struct iface *iface, const struct rte_ipv6_addr
}

nexthop_incref(nh);
gr_vec_add(maddrs->nh, nh);

// gr_vec_add may realloc() and free the old vector
// Duplicate the whole vector and append to the clone.
gr_vec struct nexthop **nhs_copy = NULL;
gr_vec struct nexthop **nhs_old = maddrs->nh;
gr_vec_cap_set(nhs_copy, gr_vec_len(nhs_old) + 1); // avoid malloc+realloc
gr_vec_extend(nhs_copy, nhs_old);
gr_vec_add(nhs_copy, nh);
maddrs->nh = nhs_copy;
if (nhs_old != NULL) {
// Once all datapath workers have seen the new clone, free the old one.
rte_rcu_qsbr_synchronize(gr_datapath_rcu(), RTE_QSBR_THRID_INVALID);
gr_vec_free(nhs_old);
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@maxime-leroy maxime-leroy Oct 12, 2025

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Having a real gc, not doing synchronize barrier every where seems more and more needed for grout...

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@rjarry rjarry Oct 13, 2025

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I agree. We will soon need to implement such a thing.

}

// add ethernet filter
return iface_add_eth_addr(iface->id, &mac);
Expand Down Expand Up @@ -228,7 +242,20 @@ iface6_addr_add(const struct iface *iface, const struct rte_ipv6_addr *ip, uint8
if (ret < 0)
return errno_set(-ret);

gr_vec_add(addrs->nh, nh);
// gr_vec_add may realloc() and free the old vector
// Duplicate the whole vector and append to the clone.
gr_vec struct nexthop **nhs_copy = NULL;
gr_vec struct nexthop **nhs_old = addrs->nh;
gr_vec_cap_set(nhs_copy, gr_vec_len(nhs_old) + 1); // avoid malloc+realloc
gr_vec_extend(nhs_copy, nhs_old);
gr_vec_add(nhs_copy, nh);
addrs->nh = nhs_copy;
if (nhs_old != NULL) {
// Once all datapath workers have seen the new clone, free the old one.
rte_rcu_qsbr_synchronize(gr_datapath_rcu(), RTE_QSBR_THRID_INVALID);
gr_vec_free(nhs_old);
}

gr_event_push(
GR_EVENT_IP6_ADDR_ADD,
&(struct gr_ip6_ifaddr) {
Expand Down