netdev - [PATCH net 1/3] netfilter: nft_set_pipapo: fix null deref for empty set

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Message-ID: <20250813113800.20775-2-fw@strlen.de>
Date: Wed, 13 Aug 2025 13:36:36 +0200
From: Florian Westphal <fw@...len.de>
To: <netdev@...r.kernel.org>
Cc: Paolo Abeni <pabeni@...hat.com>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>,
	<netfilter-devel@...r.kernel.org>,
	pablo@...filter.org
Subject: [PATCH net 1/3] netfilter: nft_set_pipapo: fix null deref for empty set

Blamed commit broke the check for a null scratch map:
  -  if (unlikely(!m || !*raw_cpu_ptr(m->scratch)))
  +  if (unlikely(!raw_cpu_ptr(m->scratch)))

This should have been "if (!*raw_ ...)".
Use the pattern of the avx2 version which is more readable.

This can only be reproduced if avx2 support isn't available.

Fixes: d8d871a35ca9 ("netfilter: nft_set_pipapo: merge pipapo_get/lookup")
Signed-off-by: Florian Westphal <fw@...len.de>
---
 net/netfilter/nft_set_pipapo.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/net/netfilter/nft_set_pipapo.c b/net/netfilter/nft_set_pipapo.c
index 1a19649c2851..9a10251228fd 100644
--- a/net/netfilter/nft_set_pipapo.c
+++ b/net/netfilter/nft_set_pipapo.c
@@ -426,10 +426,9 @@ static struct nft_pipapo_elem *pipapo_get(const struct nft_pipapo_match *m,
 
 	local_bh_disable();
 
-	if (unlikely(!raw_cpu_ptr(m->scratch)))
-		goto out;
-
 	scratch = *raw_cpu_ptr(m->scratch);
+	if (unlikely(!scratch))
+		goto out;
 
 	map_index = scratch->map_index;
 
-- 
2.49.1