[NETFILTER]: Fix do_add_counters race, possible oops or info leak (CVE-2006-0039)
Solar Designer found a race condition in do_add_counters(). The beginning of paddc is supposed to be the same as tmp which was sanity-checked above, but it might not be the same in reality. In case the integer overflow and/or the race condition are triggered, paddc->num_counters might not match the allocation size for paddc. If the check below (t->private->number != paddc->num_counters) nevertheless passes (perhaps this requires the race condition to be triggered), IPT_ENTRY_ITERATE() would read kernel memory beyond the allocation size, potentially causing an oops or leaking sensitive data (e.g., passwords from host system or from another VPS) via counter increments. This requires CAP_NET_ADMIN. Signed-off-by: Solar Designer <solar@openwall.com> Signed-off-by: Kirill Korotaev <dev@openvz.org> Signed-off-by: Patrick McHardy <kaber@trash.net> Signed-off-by: David S. Miller <davem@davemloft.net>
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@ -948,7 +948,7 @@ static int do_add_counters(void __user *user, unsigned int len)
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write_lock_bh(&t->lock);
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write_lock_bh(&t->lock);
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private = t->private;
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private = t->private;
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if (private->number != paddc->num_counters) {
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if (private->number != tmp.num_counters) {
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ret = -EINVAL;
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ret = -EINVAL;
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goto unlock_up_free;
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goto unlock_up_free;
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}
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}
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@ -1103,7 +1103,7 @@ do_add_counters(void __user *user, unsigned int len)
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write_lock_bh(&t->lock);
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write_lock_bh(&t->lock);
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private = t->private;
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private = t->private;
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if (private->number != paddc->num_counters) {
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if (private->number != tmp.num_counters) {
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ret = -EINVAL;
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ret = -EINVAL;
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goto unlock_up_free;
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goto unlock_up_free;
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}
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}
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