On Sat, 2007-11-10 at 00:12 +0100, Patrick McHardy wrote:
> This may cause a use-after-free since __dev_addr_delete frees the address
> when all references are gone.
How about a comment then? Perhaps:
diff --git a/net/core/dev_mcast.c b/net/core/dev_mcast.c
index ae35405..63576aa 100644
--- a/net/core/dev_mcast.c
+++ b/net/core/dev_mcast.c
@@ -165,16 +165,23 @@ void dev_mc_unsync(struct net_device *to, struct net_device *from)
netif_tx_lock_bh(from);
netif_tx_lock_bh(to);
+ /*
+ This while loop can't be written as
+ for (da = from->mc_list; da; da = da->next)
+ da = from->mc_list and __dev_addr_delete can kfree(from->mc_list)
+ which could cause a use-after-free of da->next
+ */
+
da = from->mc_list;
while (da != NULL) {
next = da->next;
- if (!da->da_synced)
- continue;
- __dev_addr_delete(&to->mc_list, &to->mc_count,
- da->da_addr, da->da_addrlen, 0);
- da->da_synced = 0;
- __dev_addr_delete(&from->mc_list, &from->mc_count,
- da->da_addr, da->da_addrlen, 0);
+ if (da->da_synced) {
+ __dev_addr_delete(&to->mc_list, &to->mc_count,
+ da->da_addr, da->da_addrlen, 0);
+ da->da_synced = 0;
+ __dev_addr_delete(&from->mc_list, &from->mc_count,
+ da->da_addr, da->da_addrlen, 0);
+ }
da = next;
}
__dev_set_rx_mode(to);
-
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