netdev - [PATCH v2] netfilter: amanda: fix RCU pointer typing for nf_nat_amanda

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Message-ID: <20260203145511.164485-1-sun.jian.kdev@gmail.com>
Date: Tue,  3 Feb 2026 22:55:11 +0800
From: Sun Jian <sun.jian.kdev@...il.com>
To: Florian Westphal <fw@...len.de>
Cc: Pablo Neira Ayuso <pablo@...filter.org>,
	Phil Sutter <phil@....cc>,
	Simon Horman <horms@...nel.org>,
	netfilter-devel@...r.kernel.org,
	netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Sun Jian <sun.jian.kdev@...il.com>
Subject: [PATCH v2] netfilter: amanda: fix RCU pointer typing for nf_nat_amanda_hook

Sparse reports "incompatible types in comparison expression" error in
nf_conntrack_amanda.c because nf_nat_amanda_hook is used with
rcu_dereference() but lacks the proper __rcu annotation.

Fix this by correctly placing the __rcu annotation inside the pointer
parentheses in both the declaration and definition. This allows the
standard rcu_dereference() to work correctly.

Suggested-by: Florian Westphal <fw@...len.de>
Signed-off-by: Sun Jian <sun.jian.kdev@...il.com>
---
v2:
  - Correctly place __rcu annotation inside the parentheses as
    suggested by Florian Westphal.
  - Use standard rcu_dereference() instead of rcu_dereference_raw().
---
 include/linux/netfilter/nf_conntrack_amanda.h | 12 +++++------
 net/netfilter/nf_conntrack_amanda.c           | 21 ++++++++++++-------
 2 files changed, 19 insertions(+), 14 deletions(-)

diff --git a/include/linux/netfilter/nf_conntrack_amanda.h b/include/linux/netfilter/nf_conntrack_amanda.h
index 6f0ac896fcc9..9f957598a9da 100644
--- a/include/linux/netfilter/nf_conntrack_amanda.h
+++ b/include/linux/netfilter/nf_conntrack_amanda.h
@@ -7,10 +7,10 @@
 #include <linux/skbuff.h>
 #include <net/netfilter/nf_conntrack_expect.h>
 
-extern unsigned int (*nf_nat_amanda_hook)(struct sk_buff *skb,
-					  enum ip_conntrack_info ctinfo,
-					  unsigned int protoff,
-					  unsigned int matchoff,
-					  unsigned int matchlen,
-					  struct nf_conntrack_expect *exp);
+extern unsigned int (__rcu *nf_nat_amanda_hook)(struct sk_buff *skb,
+						enum ip_conntrack_info ctinfo,
+						unsigned int protoff,
+						unsigned int matchoff,
+						unsigned int matchlen,
+						struct nf_conntrack_expect *exp);
 #endif /* _NF_CONNTRACK_AMANDA_H */
diff --git a/net/netfilter/nf_conntrack_amanda.c b/net/netfilter/nf_conntrack_amanda.c
index 7be4c35e4795..2e3753758b9b 100644
--- a/net/netfilter/nf_conntrack_amanda.c
+++ b/net/netfilter/nf_conntrack_amanda.c
@@ -37,13 +37,13 @@ MODULE_PARM_DESC(master_timeout, "timeout for the master connection");
 module_param(ts_algo, charp, 0400);
 MODULE_PARM_DESC(ts_algo, "textsearch algorithm to use (default kmp)");
 
-unsigned int (*nf_nat_amanda_hook)(struct sk_buff *skb,
-				   enum ip_conntrack_info ctinfo,
-				   unsigned int protoff,
-				   unsigned int matchoff,
-				   unsigned int matchlen,
-				   struct nf_conntrack_expect *exp)
-				   __read_mostly;
+unsigned int (__rcu *nf_nat_amanda_hook)(struct sk_buff *skb,
+					 enum ip_conntrack_info ctinfo,
+					 unsigned int protoff,
+					 unsigned int matchoff,
+					 unsigned int matchlen,
+					 struct nf_conntrack_expect *exp)
+					 __read_mostly;
 EXPORT_SYMBOL_GPL(nf_nat_amanda_hook);
 
 enum amanda_strings {
@@ -98,7 +98,12 @@ static int amanda_help(struct sk_buff *skb,
 	u_int16_t len;
 	__be16 port;
 	int ret = NF_ACCEPT;
-	typeof(nf_nat_amanda_hook) nf_nat_amanda;
+	unsigned int (*nf_nat_amanda)(struct sk_buff *skb,
+				      enum ip_conntrack_info ctinfo,
+				      unsigned int protoff,
+				      unsigned int matchoff,
+				      unsigned int matchlen,
+				      struct nf_conntrack_expect *exp);
 
 	/* Only look at packets from the Amanda server */
 	if (CTINFO2DIR(ctinfo) == IP_CT_DIR_ORIGINAL)
-- 
2.43.0