[PATCH nf-next 9/9] netfilter: nft_immediate: cancel register tracking for data destination register

[Pablo Neira Ayuso <pablo@netfilter.org>]

The immediate expression might clobber existing data on the registers,
cancel register tracking for the destination register.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
 net/netfilter/nft_immediate.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/net/netfilter/nft_immediate.c b/net/netfilter/nft_immediate.c
index d0f67d325bdf..daf1463ccdcb 100644
--- a/net/netfilter/nft_immediate.c
+++ b/net/netfilter/nft_immediate.c
@@ -223,6 +223,17 @@ static bool nft_immediate_offload_action(const struct nft_expr *expr)
 	return false;
 }
 
+static bool nft_immediate_reduce(struct nft_regs_track *track,
+				 const struct nft_expr *expr)
+{
+	const struct nft_immediate_expr *priv = nft_expr_priv(expr);
+
+	if (priv->dreg != NFT_REG_VERDICT)
+		__nft_reg_track_cancel(track, priv->dreg);
+
+	return false;
+}
+
 static const struct nft_expr_ops nft_imm_ops = {
 	.type		= &nft_imm_type,
 	.size		= NFT_EXPR_SIZE(sizeof(struct nft_immediate_expr)),
@@ -233,6 +244,7 @@ static const struct nft_expr_ops nft_imm_ops = {
 	.destroy	= nft_immediate_destroy,
 	.dump		= nft_immediate_dump,
 	.validate	= nft_immediate_validate,
+	.reduce		= nft_immediate_reduce,
 	.offload	= nft_immediate_offload,
 	.offload_action	= nft_immediate_offload_action,
 };
-- 
2.30.2