netfilter: nft_numgen: fix race between num generate and store it
After we generate a new number, we still use the priv->counter and
store it to the dreg. This is not correct, another cpu may already
change it to a new number. So we must use the generated number, not
the priv->counter itself.
Fixes: 91dbc6be0a
("netfilter: nf_tables: add number generator expression")
Signed-off-by: Liping Zhang <liping.zhang@spreadtrum.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
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@ -37,7 +37,7 @@ static void nft_ng_inc_eval(const struct nft_expr *expr,
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nval = (oval + 1 < priv->modulus) ? oval + 1 : 0;
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} while (atomic_cmpxchg(&priv->counter, oval, nval) != oval);
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memcpy(®s->data[priv->dreg], &priv->counter, sizeof(u32));
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regs->data[priv->dreg] = nval;
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}
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static const struct nla_policy nft_ng_policy[NFTA_NG_MAX + 1] = {
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