linux-kernel - [PATCH] Fix initializing a static union variable

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Message-ID: <20240620181736.1270455-1-yabinc@google.com>
Date: Thu, 20 Jun 2024 11:17:36 -0700
From: Yabin Cui <yabinc@...gle.com>
To: Steffen Klassert <steffen.klassert@...unet.com>, Herbert Xu <herbert@...dor.apana.org.au>, 
	"David S. Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>, 
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>, 
	Nathan Chancellor <nathan@...nel.org>, Nick Desaulniers <ndesaulniers@...gle.com>, 
	Bill Wendling <morbo@...gle.com>, Justin Stitt <justinstitt@...gle.com>
Cc: netdev@...r.kernel.org, linux-kernel@...r.kernel.org, llvm@...ts.linux.dev, 
	Yabin Cui <yabinc@...gle.com>
Subject: [PATCH] Fix initializing a static union variable

saddr_wildcard is a static union variable initialized with {}.
But c11 standard doesn't guarantee initializing all fields as
zero for this case. As in https://godbolt.org/z/rWvdv6aEx,
clang only initializes the first field as zero, but the bits
corresponding to other (larger) members are undefined.

Signed-off-by: Yabin Cui <yabinc@...gle.com>
---
 net/xfrm/xfrm_state.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/xfrm/xfrm_state.c b/net/xfrm/xfrm_state.c
index 649bb739df0d..9bc69d703e5c 100644
--- a/net/xfrm/xfrm_state.c
+++ b/net/xfrm/xfrm_state.c
@@ -1139,7 +1139,7 @@ xfrm_state_find(const xfrm_address_t *daddr, const xfrm_address_t *saddr,
 		struct xfrm_policy *pol, int *err,
 		unsigned short family, u32 if_id)
 {
-	static xfrm_address_t saddr_wildcard = { };
+	static const xfrm_address_t saddr_wildcard;
 	struct net *net = xp_net(pol);
 	unsigned int h, h_wildcard;
 	struct xfrm_state *x, *x0, *to_put;
-- 
2.45.2.741.gdbec12cfda-goog