linux-hardening - [PATCH] net: core: use __counted_by for trailing VLA of struct sock

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Message-ID: <20240730160449.368698-1-dmantipov@yandex.ru>
Date: Tue, 30 Jul 2024 19:04:49 +0300
From: Dmitry Antipov <dmantipov@...dex.ru>
To: Paolo Abeni <pabeni@...hat.com>
Cc: Kees Cook <kees@...nel.org>,
	netdev@...r.kernel.org,
	linux-hardening@...r.kernel.org,
	Dmitry Antipov <dmantipov@...dex.ru>
Subject: [PATCH] net: core: use __counted_by for trailing VLA of struct sock_reuseport

According to '__reuseport_alloc()', annotate trailing VLA 'sock' of
'struct sock_reuseport' with '__counted_by()' and use convenient
'struct_size()' to simplify the math used in 'kzalloc()'.

Signed-off-by: Dmitry Antipov <dmantipov@...dex.ru>
---
 include/net/sock_reuseport.h | 2 +-
 net/core/sock_reuseport.c    | 7 +++----
 2 files changed, 4 insertions(+), 5 deletions(-)

diff --git a/include/net/sock_reuseport.h b/include/net/sock_reuseport.h
index 6ec140b0a61b..6e4faf3ee76f 100644
--- a/include/net/sock_reuseport.h
+++ b/include/net/sock_reuseport.h
@@ -26,7 +26,7 @@ struct sock_reuseport {
 	unsigned int		bind_inany:1;
 	unsigned int		has_conns:1;
 	struct bpf_prog __rcu	*prog;		/* optional BPF sock selector */
-	struct sock		*socks[];	/* array of sock pointers */
+	struct sock		*socks[] __counted_by(max_socks);
 };
 
 extern int reuseport_alloc(struct sock *sk, bool bind_inany);
diff --git a/net/core/sock_reuseport.c b/net/core/sock_reuseport.c
index 5a165286e4d8..5eea73aaeb0f 100644
--- a/net/core/sock_reuseport.c
+++ b/net/core/sock_reuseport.c
@@ -173,11 +173,10 @@ static bool __reuseport_detach_closed_sock(struct sock *sk,
 
 static struct sock_reuseport *__reuseport_alloc(unsigned int max_socks)
 {
-	unsigned int size = sizeof(struct sock_reuseport) +
-		      sizeof(struct sock *) * max_socks;
-	struct sock_reuseport *reuse = kzalloc(size, GFP_ATOMIC);
+	struct sock_reuseport *reuse =
+		kzalloc(struct_size(reuse, socks, max_socks), GFP_ATOMIC);
 
-	if (!reuse)
+	if (unlikely(!reuse))
 		return NULL;
 
 	reuse->max_socks = max_socks;
-- 
2.45.2