[net-next,11/19] netfilter: nft_immediate: cancel register tracking for data destination register

Commit Message

Pablo Neira Ayuso March 21, 2022, 12:30 p.m. UTC

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

Signed-off-by: Pablo Neira Ayuso <[e-mail]>
---
 net/netfilter/nft_immediate.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

Patch

diff --git a/net/netfilter/nft_immediate.c b/net/netfilter/nft_immediate.c
index d0f67d325bdf..b80f7b507349 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, priv->dlen);
+
+	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,
 };